diff --git a/test/staging/sm/Array/change-array-by-copy-errors-from-correct-realm.js b/test/staging/sm/Array/change-array-by-copy-errors-from-correct-realm.js
index f3a8ec5af4..466e4ef529 100644
--- a/test/staging/sm/Array/change-array-by-copy-errors-from-correct-realm.js
+++ b/test/staging/sm/Array/change-array-by-copy-errors-from-correct-realm.js
@@ -60,25 +60,11 @@ function test(otherGlobal) {
     // For each erroneous case, make sure the error comes from
     // the other realm (not this realm)
     for (const [message, f] of typeErrorCalls) {
-        try {
-            f();
-        } catch (exc) {
-            assert.sameValue(exc instanceof TypeError, false, message + " threw TypeError from wrong realm");
-            assert.sameValue(exc instanceof otherGlobal.TypeError, true, message + " didn't throw TypeError from other realm");
-            assert.sameValue(Object.getPrototypeOf(exc) !== Object.getPrototypeOf(TypeError), true,
-                     message + " TypeError has wrong prototype");
-        }
+        assert.throws(otherGlobal.TypeError, f, message);
     }
 
     for (const [message, f] of rangeErrorCalls) {
-        try {
-            f();
-        } catch (exc) {
-            assert.sameValue(exc instanceof RangeError, false, message + " threw RangeError from wrong realm");
-            assert.sameValue(exc instanceof otherGlobal.RangeError, true, message + " didn't throw RangeError from other realm");
-            assert.sameValue(Object.getPrototypeOf(exc) !== Object.getPrototypeOf(RangeError), true,
-                     message + " TypeError has wrong prototype");
-        }
+        assert.throws(otherGlobal.RangeError, f, message);
     }
 }
 
diff --git a/test/staging/sm/Array/length-set-object.js b/test/staging/sm/Array/length-set-object.js
index d24bf5174c..ed3c93b01e 100644
--- a/test/staging/sm/Array/length-set-object.js
+++ b/test/staging/sm/Array/length-set-object.js
@@ -29,16 +29,9 @@ invokeConversionTwice2();
 
 function dontOverwriteError1()
 {
-  try
-  {
+  assert.throws(TypeError, function() {
     [].length = { valueOf: {}, toString: {} };
-    throw new Error("didn't throw a TypeError");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "expected a TypeError running out of conversion options, got " + e);
-  }
+  }, "expected a TypeError running out of conversion options");
 }
 dontOverwriteError1();
 
diff --git a/test/staging/sm/Array/length-truncate-nonconfigurable-sparse.js b/test/staging/sm/Array/length-truncate-nonconfigurable-sparse.js
index 7869915e61..7eee512f27 100644
--- a/test/staging/sm/Array/length-truncate-nonconfigurable-sparse.js
+++ b/test/staging/sm/Array/length-truncate-nonconfigurable-sparse.js
@@ -73,16 +73,9 @@ function strict()
 
   addDataProperty(arr,  27182818, "eep", false, false, false);
 
-  try
-  {
+  assert.throws(TypeError, function() {
     arr.length = 1;
-    throw new Error("didn't throw?!");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "non-configurable property should trigger TypeError, got " + e);
-  }
+  }, "non-configurable property should trigger TypeError");
 
   assert.sameValue(arr.length, 27182819);
 
diff --git a/test/staging/sm/Array/length-truncate-nonconfigurable.js b/test/staging/sm/Array/length-truncate-nonconfigurable.js
index c95e96063b..60bc8619ec 100644
--- a/test/staging/sm/Array/length-truncate-nonconfigurable.js
+++ b/test/staging/sm/Array/length-truncate-nonconfigurable.js
@@ -14,16 +14,9 @@ esid: pending
 var arr = [0, 1, 2];
 Object.defineProperty(arr, 1, { configurable: false });
 
-try
-{
+assert.throws(TypeError, function() {
   Object.defineProperty(arr, "length", { value: 0, writable: false });
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "must throw TypeError when array truncation would have to remove " +
-           "non-configurable elements");
-}
+}, "must throw TypeError when array truncation would have to remove non-configurable elements");
 
 assert.sameValue(arr.length, 2, "length is highest remaining index plus one");
 
diff --git a/test/staging/sm/Array/pop-empty-nonwritable.js b/test/staging/sm/Array/pop-empty-nonwritable.js
index 858c2f50f3..a59c120010 100644
--- a/test/staging/sm/Array/pop-empty-nonwritable.js
+++ b/test/staging/sm/Array/pop-empty-nonwritable.js
@@ -11,13 +11,6 @@ description: |
 esid: pending
 ---*/
 
-try
-{
+assert.throws(TypeError, function() {
   Object.freeze([]).pop();
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown TypeError, instead got: " + e);
-}
+});
diff --git a/test/staging/sm/Array/redefine-nonwritable-length-custom-conversion-throw.js b/test/staging/sm/Array/redefine-nonwritable-length-custom-conversion-throw.js
index 88fc4811e7..25179a8db0 100644
--- a/test/staging/sm/Array/redefine-nonwritable-length-custom-conversion-throw.js
+++ b/test/staging/sm/Array/redefine-nonwritable-length-custom-conversion-throw.js
@@ -27,8 +27,7 @@ var convertible =
 var arr = [];
 Object.defineProperty(arr, "length", { value: 0, writable: false });
 
-try
-{
+assert.throws(SyntaxError, function() {
   Object.defineProperty(arr, "length",
                         {
                           value: convertible,
@@ -36,12 +35,7 @@ try
                           configurable: true,
                           enumerable: true
                         });
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true, "expected SyntaxError, got " + e);
-}
+});
 
 assert.sameValue(count, 1);
 assert.sameValue(arr.length, 0);
diff --git a/test/staging/sm/Date/toISOString.js b/test/staging/sm/Date/toISOString.js
index 19d23a241b..934d3d4ded 100644
--- a/test/staging/sm/Date/toISOString.js
+++ b/test/staging/sm/Date/toISOString.js
@@ -10,20 +10,16 @@ description: |
   pending
 esid: pending
 ---*/
+
 function throwsRangeError(t) {
-    try {
-        var date = new Date();
-        date.setTime(t);
-        var r = date.toISOString();
-        throw new Error("toISOString didn't throw, instead returned " + r);
-    } catch (err) {
-        assert.sameValue(err instanceof RangeError, true, 'wrong error: ' + err);
-        return;
-    }
-    assert.sameValue(0, 1, 'not good, nyan, nyan');
+  var date = new Date();
+  date.setTime(t);
+
+  assert.throws(RangeError, function() {
+    date.toISOString();
+  });
 }
 
 throwsRangeError(Infinity);
 throwsRangeError(-Infinity);
 throwsRangeError(NaN);
-
diff --git a/test/staging/sm/Date/toJSON-01.js b/test/staging/sm/Date/toJSON-01.js
index 81adf58531..f1ed1c340c 100644
--- a/test/staging/sm/Date/toJSON-01.js
+++ b/test/staging/sm/Date/toJSON-01.js
@@ -30,27 +30,13 @@ assert.sameValue(dateToJSON.length, 1);
  * 1. Let O be the result of calling ToObject, giving it the this value as its
  *    argument.
  */
-try
-{
+assert.throws(TypeError, function() {
   dateToJSON.call(null);
-  throw new Error("should have thrown a TypeError");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "ToObject throws TypeError for null/undefined");
-}
+}, "ToObject throws TypeError for null");
 
-try
-{
+assert.throws(TypeError, function() {
   dateToJSON.call(undefined);
-  throw new Error("should have thrown a TypeError");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "ToObject throws TypeError for null/undefined");
-}
+}, "ToObject throws TypeError for undefined");
 
 
 /*
@@ -123,19 +109,13 @@ assert.sameValue(dateToJSON.call({ valueOf: function() { called = true; return {
          NaN);
 assert.sameValue(asserted, true);
 
-try
-{
+assert.throws(TypeError, function() {
   var r = dateToJSON.call({ valueOf: null, toString: null,
                             get toISOString()
                             {
                               throw new Error("shouldn't have been gotten");
                             } });
-  throw new Error("didn't throw, returned: " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "bad exception: " + e);
-}
+});
 
 
 /* 3. If tv is a Number and is not finite, return null. */
@@ -167,45 +147,21 @@ catch (e)
 
 
 /* 5. If IsCallable(toISO) is false, throw a TypeError exception. */
-try
-{
-  var r = dateToJSON.call({ toISOString: null });
-  throw new Error("didn't throw, returned: " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "bad exception: " + e);
-}
+assert.throws(TypeError, function() {
+  dateToJSON.call({ toISOString: null });
+});
 
-try
-{
-  var r = dateToJSON.call({ toISOString: undefined });
-  throw new Error("didn't throw, returned: " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "bad exception: " + e);
-}
+assert.throws(TypeError, function() {
+  dateToJSON.call({ toISOString: undefined });
+});
 
-try
-{
-  var r = dateToJSON.call({ toISOString: "oogabooga" });
-  throw new Error("didn't throw, returned: " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "bad exception: " + e);
-}
+assert.throws(TypeError, function() {
+  dateToJSON.call({ toISOString: "oogabooga" });
+});
 
-try
-{
-  var r = dateToJSON.call({ toISOString: Math.PI });
-  throw new Error("didn't throw, returned: " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "bad exception: " + e);
-}
+assert.throws(TypeError, function() {
+  dateToJSON.call({ toISOString: Math.PI });
+});
 
 
 /*
diff --git a/test/staging/sm/Function/15.3.4.3-01.js b/test/staging/sm/Function/15.3.4.3-01.js
index 565d772a8e..3e6571e362 100644
--- a/test/staging/sm/Function/15.3.4.3-01.js
+++ b/test/staging/sm/Function/15.3.4.3-01.js
@@ -11,19 +11,6 @@ description: |
 esid: pending
 ---*/
 
-function expectTypeError(fun, msg)
-{
-  try
-  {
-    fun();
-    assert.sameValue(true, false, "should have thrown a TypeError");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true, msg + "; instead threw " + e);
-  }
-}
-
 function fun() { }
 
 var global = this;
@@ -39,7 +26,7 @@ for (var i = 0, sz = nonfuns.length; i < sz; i++)
   };
   var msg =
     "expected TypeError calling Function.prototype.apply with uncallable this";
-  expectTypeError(f, msg);
+  assert.throws(TypeError, f, msg);
 }
 
 
@@ -123,7 +110,7 @@ for (var i = 0, sz = nonobjs.length; i < sz; i++)
 {
   var f = function() { fun.apply(thisObj, nonobjs[i]); };
   var msg = "should have thrown a TypeError with non-object arguments";
-  expectTypeError(f, msg);
+  assert.throws(TypeError, f, msg);
 }
 
 
diff --git a/test/staging/sm/Function/arguments-caller-callee.js b/test/staging/sm/Function/arguments-caller-callee.js
index bb253dd4b6..c0cfb8da48 100644
--- a/test/staging/sm/Function/arguments-caller-callee.js
+++ b/test/staging/sm/Function/arguments-caller-callee.js
@@ -13,24 +13,9 @@ esid: pending
 
 // behavior
 
-function expectTypeError(fun)
-{
-  try
-  {
-    fun();
-    throw new Error("didn't throw");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "expected TypeError calling function" +
-             ("name" in fun ? " " + fun.name : "") + ", instead got: " + e);
-  }
-}
-
 function bar() { "use strict"; return arguments; }
 assert.sameValue(bar().caller, undefined); // No error when accessing arguments.caller in ES2017+
-expectTypeError(function barCallee() { bar().callee; });
+assert.throws(TypeError, function barCallee() { bar().callee; });
 
 function baz() { return arguments; }
 assert.sameValue(baz().callee, baz);
diff --git a/test/staging/sm/Function/builtin-no-construct.js b/test/staging/sm/Function/builtin-no-construct.js
index a9d803162c..2ecda81be3 100644
--- a/test/staging/sm/Function/builtin-no-construct.js
+++ b/test/staging/sm/Function/builtin-no-construct.js
@@ -10,13 +10,11 @@ description: |
   pending
 esid: pending
 ---*/
+
 function checkMethod(method) {
-    try {
+    assert.throws(TypeError, function() {
         new method();
-        assert.sameValue(0, 1, "not reached " + method);
-    } catch (e) {
-        assert.sameValue(e.message.indexOf(" is not a constructor") === -1, false);
-    }
+    });
 }
 
 function checkMethods(proto) {
@@ -54,4 +52,3 @@ var builtin_funcs = [
 for (var i = 0; i < builtin_funcs.length; i++) {
     checkMethod(builtin_funcs[i]);
 }
-
diff --git a/test/staging/sm/Function/function-bind.js b/test/staging/sm/Function/function-bind.js
index cec3cd85ea..5c2daf59c7 100644
--- a/test/staging/sm/Function/function-bind.js
+++ b/test/staging/sm/Function/function-bind.js
@@ -180,11 +180,9 @@ assert.sameValue(one.bind(null, 1, 2).length, 0);
 
 // retch
 var br = Object.create(null, { length: { value: 0 } });
-try
-{
-  br = bind.call(/a/g, /a/g, "aaaa");
-}
-catch (e) { /* nothing */ }
+assert.throws(TypeError, function() {
+  bind.call(/a/g, /a/g, "aaaa");
+});
 assert.sameValue(br.length, 0);
 
 
diff --git a/test/staging/sm/Function/function-call.js b/test/staging/sm/Function/function-call.js
index f4e0dc554a..0515d2e08b 100644
--- a/test/staging/sm/Function/function-call.js
+++ b/test/staging/sm/Function/function-call.js
@@ -11,19 +11,6 @@ description: |
 esid: pending
 ---*/
 
-function expectTypeError(fun, msg)
-{
-  try
-  {
-    fun();
-    assert.sameValue(true, false, "should have thrown a TypeError");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true, msg + "; instead threw " + e);
-  }
-}
-
 function fun() { }
 
 var global = this;
@@ -41,7 +28,7 @@ for (var i = 0, sz = nonfuns.length; i < sz; i++)
   };
   var msg =
     "expected TypeError calling Function.prototype.call with uncallable this";
-  expectTypeError(f, msg);
+  assert.throws(TypeError, f, msg);
 }
 
 
diff --git a/test/staging/sm/Function/function-caller.js b/test/staging/sm/Function/function-caller.js
index 60bd813866..aeaf282f99 100644
--- a/test/staging/sm/Function/function-caller.js
+++ b/test/staging/sm/Function/function-caller.js
@@ -11,23 +11,8 @@ description: |
 esid: pending
 ---*/
 
-function expectTypeError(fun)
-{
-  try
-  {
-    fun();
-    throw new Error("didn't throw");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "expected TypeError calling function" +
-             ("name" in fun ? " " + fun.name : "") + ", instead got: " + e);
-  }
-}
-
 function bar() { "use strict"; }
-expectTypeError(function barCaller() { bar.caller; });
+assert.throws(TypeError, function barCaller() { bar.caller; });
 
 function baz() { "use strict"; return 17; }
-expectTypeError(function bazCaller() { baz.caller; });
+assert.throws(TypeError, function bazCaller() { baz.caller; });
diff --git a/test/staging/sm/Function/function-name.js b/test/staging/sm/Function/function-name.js
index bc1a6e1408..e1cf804624 100644
--- a/test/staging/sm/Function/function-name.js
+++ b/test/staging/sm/Function/function-name.js
@@ -23,25 +23,17 @@ function testFunctionName(f) {
 function testFunctionNameStrict(f) {
     "use strict";
     var name = f.name;
-    var error;
-    try {
+    assert.throws(TypeError, function() {
         f.name = 'g';
-    } catch (e) {
-        error = e;
-    }
+    });
     assert.sameValue(f.name, name);
-    assert.sameValue(error instanceof TypeError, true);
     assert.sameValue(delete f.name, true);
     assert.sameValue(f.name, '');
     assert.sameValue(f.hasOwnProperty('name'), false);
-    error = null;
-    try {
+    assert.throws(TypeError, function() {
         f.name = 'g';
-    } catch (e) {
-        error = e;
-    }
+    });
     assert.sameValue(f.name, '');
-    assert.sameValue(error instanceof TypeError, true);
     Object.defineProperty(f, 'name', {value: 'g'});
     assert.sameValue(f.name, 'g');
 }
diff --git a/test/staging/sm/JSON/cyclic-stringify.js b/test/staging/sm/JSON/cyclic-stringify.js
index d8d69026c7..0872df47ee 100644
--- a/test/staging/sm/JSON/cyclic-stringify.js
+++ b/test/staging/sm/JSON/cyclic-stringify.js
@@ -22,33 +22,17 @@ var desc =
   };
 var obj = Object.defineProperty({ p1: 0 }, "p2", desc);
 
-try
-{
-  var str = JSON.stringify(obj);
-  assert.sameValue(false, true, "should have thrown, got " + str);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "wrong error type: " + e.constructor.name);
-  assert.sameValue(count, 1,
-           "cyclic data structures not detected immediately");
-}
+assert.throws(TypeError, function() {
+  JSON.stringify(obj);
+});
+assert.sameValue(count, 1, "cyclic data structures not detected immediately");
 
 count = 0;
 var obj2 = Object.defineProperty({}, "obj", desc);
-try
-{
-  var str = JSON.stringify(obj2);
-  assert.sameValue(false, true, "should have thrown, got " + str);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "wrong error type: " + e.constructor.name);
-  assert.sameValue(count, 2,
-           "cyclic data structures not detected immediately");
-}
+assert.throws(TypeError, function() {
+  JSON.stringify(obj2);
+});
+assert.sameValue(count, 2, "cyclic data structures not detected immediately");
 
 
 // arrays
@@ -62,30 +46,14 @@ var desc =
   };
 var arr = Object.defineProperty([], "0", desc);
 
-try
-{
-  var str = JSON.stringify(arr);
-  assert.sameValue(false, true, "should have thrown, got " + str);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "wrong error type: " + e.constructor.name);
-  assert.sameValue(count, 1,
-           "cyclic data structures not detected immediately");
-}
+assert.throws(TypeError, function() {
+  JSON.stringify(arr);
+});
+assert.sameValue(count, 1, "cyclic data structures not detected immediately");
 
 count = 0;
 var arr2 = Object.defineProperty([], "0", desc);
-try
-{
-  var str = JSON.stringify(arr2);
-  assert.sameValue(false, true, "should have thrown, got " + str);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "wrong error type: " + e.constructor.name);
-  assert.sameValue(count, 2,
-           "cyclic data structures not detected immediately");
-}
+assert.throws(TypeError, function() {
+  JSON.stringify(arr2);
+});
+assert.sameValue(count, 2, "cyclic data structures not detected immediately");
diff --git a/test/staging/sm/JSON/parse-arguments.js b/test/staging/sm/JSON/parse-arguments.js
index 99a0ba80d7..618adc78de 100644
--- a/test/staging/sm/JSON/parse-arguments.js
+++ b/test/staging/sm/JSON/parse-arguments.js
@@ -11,12 +11,6 @@ description: |
 esid: pending
 ---*/
 
-try
-{
-  var r = JSON.parse();
-  throw new Error("didn't throw, returned " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true, "expected syntax error, got: " + e);
-}
+assert.throws(SyntaxError, function() {
+  JSON.parse();
+});
diff --git a/test/staging/sm/JSON/parse-reviver.js b/test/staging/sm/JSON/parse-reviver.js
index c449f48690..aa3b2852e2 100644
--- a/test/staging/sm/JSON/parse-reviver.js
+++ b/test/staging/sm/JSON/parse-reviver.js
@@ -37,13 +37,7 @@ function dontCallMe(k, v)
   called = true;
 }
 
-try
-{
+assert.throws(SyntaxError, function() {
   JSON.parse('{{{{{{{}}}}', dontCallMe);
-  throw new Error("didn't throw?");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true, "wrong exception: " + e);
-}
+});
 assert.sameValue(called, false);
diff --git a/test/staging/sm/JSON/stringify-boxed-primitives.js b/test/staging/sm/JSON/stringify-boxed-primitives.js
index 78e991e839..b2b356cadb 100644
--- a/test/staging/sm/JSON/stringify-boxed-primitives.js
+++ b/test/staging/sm/JSON/stringify-boxed-primitives.js
@@ -51,34 +51,25 @@ redefine(Object.prototype, "valueOf", objValueOf);
 
 redefine(Number.prototype, "toString", function() { return 42; });
 assert.sameValue(JSON.stringify(new Number(5)), "5");
+
 redefine(Number.prototype, "valueOf", function() { return 17; });
 assert.sameValue(JSON.stringify(new Number(5)), "17");
+
 delete Number.prototype.toString;
 assert.sameValue(JSON.stringify(new Number(5)), "17");
+
 delete Number.prototype.valueOf;
 assert.sameValue(JSON.stringify(new Number(5)), "null"); // isNaN(Number("[object Number]"))
+
 delete Object.prototype.toString;
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(new Number(5));
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "ToNumber failure, should throw TypeError");
-}
+}, "ToNumber failure, should throw TypeError");
+
 delete Object.prototype.valueOf;
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(new Number(5));
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "ToNumber failure, should throw TypeError");
-}
+}, "ToNumber failure, should throw TypeError");
 
 
 redefine(Number.prototype, "toString", numToString);
@@ -89,31 +80,22 @@ redefine(Object.prototype, "valueOf", objValueOf);
 
 redefine(String.prototype, "valueOf", function() { return 17; });
 assert.sameValue(JSON.stringify(new String(5)), '"5"');
+
 redefine(String.prototype, "toString", function() { return 42; });
 assert.sameValue(JSON.stringify(new String(5)), '"42"');
+
 delete String.prototype.toString;
 assert.sameValue(JSON.stringify(new String(5)), '"[object String]"');
+
 delete Object.prototype.toString;
 assert.sameValue(JSON.stringify(new String(5)), '"17"');
+
 delete String.prototype.valueOf;
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(new String(5));
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "ToString failure, should throw TypeError");
-}
+}, "ToString failure, should throw TypeError");
+
 delete Object.prototype.valueOf;
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(new String(5));
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "ToString failure, should throw TypeError");
-}
+}, "ToString failure, should throw TypeError");
diff --git a/test/staging/sm/JSON/stringify-replacer.js b/test/staging/sm/JSON/stringify-replacer.js
index dbc666ffef..d326525fc0 100644
--- a/test/staging/sm/JSON/stringify-replacer.js
+++ b/test/staging/sm/JSON/stringify-replacer.js
@@ -127,33 +127,15 @@ assert.sameValue(x, '{"0":0,"1":null,"2":2}');
 x = JSON.stringify(foo, returnStringForUndefined);
 assert.sameValue(x, '{"0":0,"1":1,"2":2,"3":"undefined value"}');
 
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(foo, returnCycleObjectFor1);
-  throw new Error("no error thrown");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "no TypeError thrown: " + e);
-}
+});
 
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(foo, returnCycleArrayFor1);
-  throw new Error("no error thrown");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "no TypeError thrown: " + e);
-}
+});
 
 foo = [0, 1, 2, undefined];
-try
-{
+assert.throws(TypeError, function() {
   JSON.stringify(foo, returnCycleObjectFor1);
-  throw new Error("no error thrown");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true, "no TypeError thrown: " + e);
-}
+});
diff --git a/test/staging/sm/Number/0x-without-following-hexdigits.js b/test/staging/sm/Number/0x-without-following-hexdigits.js
index 9283ac9ea4..f89e4dfe2c 100644
--- a/test/staging/sm/Number/0x-without-following-hexdigits.js
+++ b/test/staging/sm/Number/0x-without-following-hexdigits.js
@@ -11,13 +11,6 @@ description: |
 esid: pending
 ---*/
 
-try
-{
+assert.throws(SyntaxError, function() {
   eval("0x");
-  throw new Error("didn't throw parsing 0x (with no subsequent hex digits)");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "bad exception thrown: " + e);
-}
+});
diff --git a/test/staging/sm/Number/conversion-invalid-precision.js b/test/staging/sm/Number/conversion-invalid-precision.js
index 67a5d8cfa0..7f6a695f4f 100644
--- a/test/staging/sm/Number/conversion-invalid-precision.js
+++ b/test/staging/sm/Number/conversion-invalid-precision.js
@@ -11,19 +11,10 @@ description: |
 esid: pending
 ---*/
 
-function test(method, prec)
-{
-  try
-  {
+function test(method, prec) {
+  assert.throws(RangeError, function() {
     Number.prototype[method].call(0, prec);
-    throw "should have thrown";
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof RangeError, true,
-             "expected RangeError for " + method + " with precision " + prec +
-             ", got " + e);
-  }
+  });
 }
 
 test("toExponential", -32);
diff --git a/test/staging/sm/Number/toString-radix-handling.js b/test/staging/sm/Number/toString-radix-handling.js
index 6ebab29bb7..4931290773 100644
--- a/test/staging/sm/Number/toString-radix-handling.js
+++ b/test/staging/sm/Number/toString-radix-handling.js
@@ -11,17 +11,11 @@ description: |
 esid: pending
 ---*/
 
-function test(r)
-{
-  try
-  {
+function test(r) {
+  assert.throws(RangeError, function() {
     5..toString(r);
-    throw "should have thrown";
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof RangeError, true, "expected a RangeError, got " + e);
-  }
+  });
 }
+
 test(Math.pow(2, 32) + 10);
 test(55);
diff --git a/test/staging/sm/PrivateName/nested-class-name-used.js b/test/staging/sm/PrivateName/nested-class-name-used.js
index a8c29b6e07..d6e1650eb8 100644
--- a/test/staging/sm/PrivateName/nested-class-name-used.js
+++ b/test/staging/sm/PrivateName/nested-class-name-used.js
@@ -32,9 +32,6 @@ class A {
 };
 
 a = new A;
-try {
+assert.throws(TypeError, function() {
   a.g();
-} catch (e) {
-  assert.sameValue(e instanceof TypeError, true);
-}
-
+});
diff --git a/test/staging/sm/PrivateName/proxy-1.js b/test/staging/sm/PrivateName/proxy-1.js
index 232eb55f99..c23c4c5cec 100644
--- a/test/staging/sm/PrivateName/proxy-1.js
+++ b/test/staging/sm/PrivateName/proxy-1.js
@@ -17,13 +17,6 @@ class A {
 };
 
 var p = new Proxy(new A, {});
-var completed = false;
-try {
+assert.throws(TypeError, function() {
   p.g();
-  completed = true;
-} catch (e) {
-  assert.sameValue(e instanceof TypeError, true);
-}
-assert.sameValue(completed, false);
-
-
+});
diff --git a/test/staging/sm/PrivateName/proxy-init-set.js b/test/staging/sm/PrivateName/proxy-init-set.js
index 96bba1a2d9..240ca337e3 100644
--- a/test/staging/sm/PrivateName/proxy-init-set.js
+++ b/test/staging/sm/PrivateName/proxy-init-set.js
@@ -8,20 +8,9 @@ description: |
   pending
 esid: pending
 ---*/
+
 // Ensure that the distinction between Proxy Init and Proxy Set holds
 
-function assertThrowsTypeError(f) {
-  var type;
-  try {
-    f();
-  } catch (ex) {
-    type = ex.name;
-  }
-  assert.sameValue(type, 'TypeError');
-}
-
-
-
 var target = {};
 var p1 = new Proxy(target, {});
 var p2 = new Proxy(target, {});
@@ -60,23 +49,22 @@ assert.sameValue(A.gf(p1), 15);
 
 // Despite P1 being stamped with A's field, it shouldn't
 // be sufficient to set B's field.
-assertThrowsTypeError(() => B.sf(p1));
-assertThrowsTypeError(() => B.gf(p1));
-assertThrowsTypeError(() => B.sf(p1));
+assert.throws(TypeError, () => B.sf(p1));
+assert.throws(TypeError, () => B.gf(p1));
+assert.throws(TypeError, () => B.sf(p1));
 new B(p1);
 assert.sameValue(B.gf(p1), 25);
 B.sf(p1);
 assert.sameValue(B.gf(p1), 20);
 
 // A's field should't be on the target
-assertThrowsTypeError(() => A.gf(target));
+assert.throws(TypeError, () => A.gf(target));
 
 // Can't set the field, doesn't exist
-assertThrowsTypeError(() => A.sf(p2));
+assert.throws(TypeError, () => A.sf(p2));
 
 // Definitely can't get the field, doesn't exist.
-assertThrowsTypeError(() => A.gf(p2));
+assert.throws(TypeError, () => A.gf(p2));
 
 // Still should't be on the target.
-assertThrowsTypeError(() => A.gf(target));
-
+assert.throws(TypeError, () => A.gf(target));
diff --git a/test/staging/sm/Proxy/revocable-proxy-prototype.js b/test/staging/sm/Proxy/revocable-proxy-prototype.js
index c609f29dfc..ccd9d62c99 100644
--- a/test/staging/sm/Proxy/revocable-proxy-prototype.js
+++ b/test/staging/sm/Proxy/revocable-proxy-prototype.js
@@ -16,16 +16,9 @@ function checkFunctionAppliedToRevokedProxy(fun)
   var p = Proxy.revocable({}, {});
   p.revoke();
 
-  try
-  {
+  assert.throws(TypeError, function() {
     fun(p.proxy);
-    throw "didn't throw";
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "expected TypeError, got " + e);
-  }
+  });
 }
 
 checkFunctionAppliedToRevokedProxy(proxy => Object.getPrototypeOf(proxy));
diff --git a/test/staging/sm/RegExp/7.8.5-01.js b/test/staging/sm/RegExp/7.8.5-01.js
index 36a45dd4f7..c648b12c4b 100644
--- a/test/staging/sm/RegExp/7.8.5-01.js
+++ b/test/staging/sm/RegExp/7.8.5-01.js
@@ -17,11 +17,7 @@ var regexps = ["/\\\u000A/", "/\\\u000D/", "/\\\u2028/", "/\\\u2029/",
 
 for(var i=0; i<regexps.length; i++) {
     var src = regexps[i];
-    try {
-	x = eval(src).source;
-    } catch(e) {
-	assert.sameValue(e.constructor, SyntaxError);
-	continue;
-    }
-    assert.sameValue(0, 1);
+    assert.throws(SyntaxError, function() {
+        eval(src).source;
+    });
 }
diff --git a/test/staging/sm/RegExp/exec.js b/test/staging/sm/RegExp/exec.js
index 7777d6ebf6..3373b042d0 100644
--- a/test/staging/sm/RegExp/exec.js
+++ b/test/staging/sm/RegExp/exec.js
@@ -11,20 +11,6 @@ description: |
 esid: pending
 ---*/
 
-function expectThrowTypeError(fun)
-{
-  try
-  {
-    var r = fun();
-    throw new Error("didn't throw TypeError, returned " + r);
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "didn't throw TypeError, got: " + e);
-  }
-}
-
 function checkExec(description, regex, args, obj)
 {
   var lastIndex = obj.lastIndex;
@@ -47,15 +33,15 @@ var exec = RegExp.prototype.exec;
 var r, res, called, obj;
 
 /* 1. Let R be this RegExp object. */
-expectThrowTypeError(function() { exec.call(null); });
-expectThrowTypeError(function() { exec.call(""); });
-expectThrowTypeError(function() { exec.call(5); });
-expectThrowTypeError(function() { exec.call({}); });
-expectThrowTypeError(function() { exec.call([]); });
-expectThrowTypeError(function() { exec.call(); });
-expectThrowTypeError(function() { exec.call(true); });
-expectThrowTypeError(function() { exec.call(Object.create(RegExp.prototype)); });
-expectThrowTypeError(function() { exec.call(Object.create(/a/)); });
+assert.throws(TypeError, function() { exec.call(null); });
+assert.throws(TypeError, function() { exec.call(""); });
+assert.throws(TypeError, function() { exec.call(5); });
+assert.throws(TypeError, function() { exec.call({}); });
+assert.throws(TypeError, function() { exec.call([]); });
+assert.throws(TypeError, function() { exec.call(); });
+assert.throws(TypeError, function() { exec.call(true); });
+assert.throws(TypeError, function() { exec.call(Object.create(RegExp.prototype)); });
+assert.throws(TypeError, function() { exec.call(Object.create(/a/)); });
 
 
 /* 2. Let S be the value of ToString(string). */
@@ -109,9 +95,9 @@ assert.sameValue(r.lastIndex, obj);
  */
 r = /b/;
 r.lastIndex = { valueOf: {}, toString: {} };
-expectThrowTypeError(function() { r.exec("foopy"); });
+assert.throws(TypeError, function() { r.exec("foopy"); });
 r.lastIndex = { valueOf: function() { throw new TypeError(); } };
-expectThrowTypeError(function() { r.exec("foopy"); });
+assert.throws(TypeError, function() { r.exec("foopy"); });
 
 
 /*
diff --git a/test/staging/sm/String/match-throws-nonwritable-lastIndex-global.js b/test/staging/sm/String/match-throws-nonwritable-lastIndex-global.js
index 2d64af2c37..eb71e0b4ca 100644
--- a/test/staging/sm/String/match-throws-nonwritable-lastIndex-global.js
+++ b/test/staging/sm/String/match-throws-nonwritable-lastIndex-global.js
@@ -18,61 +18,33 @@ var s = '0x2x4x6x8';
 var p1 = /x/g;
 Object.defineProperty(p1, "lastIndex", { writable: false });
 
-try
-{
+assert.throws(TypeError, function() {
   s.match(p1);
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-}
+});
 
 // Second time with .lastIndex !== 0
 
 var p2 = /x/g;
 Object.defineProperty(p2, "lastIndex", { writable: false, value: 3 });
 
-try
-{
+assert.throws(TypeError, function() {
   s.match(p2);
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-}
+});
 
 // Third time with .lastIndex === 0, no matches
 
 var p3 = /q/g;
 Object.defineProperty(p3, "lastIndex", { writable: false });
 
-try
-{
+assert.throws(TypeError, function() {
   s.match(p3);
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-}
+});
 
 // Fourth time with .lastIndex !== 0, no matches
 
 var p4 = /q/g;
 Object.defineProperty(p4, "lastIndex", { writable: false, value: 3 });
 
-try
-{
+assert.throws(TypeError, function() {
   s.match(p4);
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-}
+});
diff --git a/test/staging/sm/String/replace-throws-nonwritable-lastIndex-global.js b/test/staging/sm/String/replace-throws-nonwritable-lastIndex-global.js
index f974d785fe..af6564bac6 100644
--- a/test/staging/sm/String/replace-throws-nonwritable-lastIndex-global.js
+++ b/test/staging/sm/String/replace-throws-nonwritable-lastIndex-global.js
@@ -18,99 +18,57 @@ var s = '0x2x4x6x8';
 var p1 = /x/g;
 Object.defineProperty(p1, "lastIndex", { writable: false });
 
-try
-{
+assert.throws(TypeError, function() {
   s.replace(p1, '');
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-  assert.sameValue(p1.lastIndex, 0);
-}
+});
+assert.sameValue(p1.lastIndex, 0);
 
 // Second time with .lastIndex !== 0, replacing to ''
 
 var p2 = /x/g;
 Object.defineProperty(p2, "lastIndex", { writable: false, value: 3 });
 
-try
-{
+assert.throws(TypeError, function() {
   s.replace(p2, '');
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-  assert.sameValue(p2.lastIndex, 3);
-}
+});
+assert.sameValue(p2.lastIndex, 3);
 
 // Third time with .lastIndex === 0, replacing to 'y'
 
 var p3 = /x/g;
 Object.defineProperty(p3, "lastIndex", { writable: false });
 
-try
-{
+assert.throws(TypeError, function() {
   s.replace(p3, 'y');
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-  assert.sameValue(p3.lastIndex, 0);
-}
+});
+assert.sameValue(p3.lastIndex, 0);
 
 // Fourth time with .lastIndex !== 0, replacing to 'y'
 
 var p4 = /x/g;
 Object.defineProperty(p4, "lastIndex", { writable: false, value: 3 });
 
-try
-{
+assert.throws(TypeError, function() {
   s.replace(p4, '');
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-  assert.sameValue(p4.lastIndex, 3);
-}
+});
+assert.sameValue(p4.lastIndex, 3);
 
 // Fifth time with .lastIndex === 0, replacing to 'y', but no match
 
 var p5 = /q/g;
 Object.defineProperty(p5, "lastIndex", { writable: false });
 
-try
-{
+assert.throws(TypeError, function() {
   s.replace(p5, 'y');
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-  assert.sameValue(p5.lastIndex, 0);
-}
+});
+assert.sameValue(p5.lastIndex, 0);
 
 // Sixth time with .lastIndex !== 0, replacing to 'y', but no match
 
 var p6 = /q/g;
 Object.defineProperty(p6, "lastIndex", { writable: false, value: 3 });
 
-try
-{
+assert.throws(TypeError, function() {
   s.replace(p6, '');
-  throw "didn't throw";
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "should have thrown a TypeError, instead got: " + e);
-  assert.sameValue(p6.lastIndex, 3);
-}
+});
+assert.sameValue(p6.lastIndex, 3);
diff --git a/test/staging/sm/TypedArray/set-negative-offset.js b/test/staging/sm/TypedArray/set-negative-offset.js
index 3ed7122a88..70d342a4f9 100644
--- a/test/staging/sm/TypedArray/set-negative-offset.js
+++ b/test/staging/sm/TypedArray/set-negative-offset.js
@@ -14,13 +14,6 @@ esid: pending
  * http://creativecommons.org/publicdomain/zero/1.0/
  */
 
-try
-{
+assert.throws(RangeError, function() {
   new Uint8Array().set([], -1);
-  throw new Error("didn't throw at all");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof RangeError, true,
-           "expected RangeError, instead got: " + e);
-}
+});
diff --git a/test/staging/sm/async-functions/await-error.js b/test/staging/sm/async-functions/await-error.js
index 3db9c60076..d57f7dc0c4 100644
--- a/test/staging/sm/async-functions/await-error.js
+++ b/test/staging/sm/async-functions/await-error.js
@@ -9,11 +9,6 @@ description: |
 esid: pending
 ---*/
 
-let caught = false;
-try {
-    eval("await 10");
-} catch(e) {
-    assert.sameValue(e.message.includes("await is only valid in"), true);
-    caught = true;
-}
-assert.sameValue(caught, true);
+assert.throws(SyntaxError, function() {
+  eval("await 10");
+});
diff --git a/test/staging/sm/class/compPropNames.js b/test/staging/sm/class/compPropNames.js
index e9e5b6d5bc..88d3add6e3 100644
--- a/test/staging/sm/class/compPropNames.js
+++ b/test/staging/sm/class/compPropNames.js
@@ -12,14 +12,9 @@ esid: pending
 
 // Function definitions.
 function syntaxError (script) {
-    try {
+    assert.throws(SyntaxError, function() {
         Function(script);
-    } catch (e) {
-        if (e instanceof SyntaxError) {
-            return;
-        }
-    }
-    throw new Error('Expected syntax error: ' + script);
+    });
 }
 
 
@@ -76,9 +71,9 @@ syntaxError("({[if (0) 0;]})");  // much less a Statement
 syntaxError("function f() { {[x]: 1} }");  // that's not even an ObjectLiteral
 syntaxError("function f() { [x]: 1 }");    // or that
 syntaxError('a = {[f1@]: "a", [f2]: "b"}'); // unexpected symbol at end of AssignmentExpression
-try { JSON.parse('{["a"]:4}'); } catch(e) {
-    if (!(e instanceof SyntaxError)) throw new Error('Expected syntax error');
-}
+assert.throws(SyntaxError, function() {
+    JSON.parse('{["a"]:4}');
+});
 
 // Property characteristics.
 a = { ["b"] : 4 };
diff --git a/test/staging/sm/class/methDefn.js b/test/staging/sm/class/methDefn.js
index 0bbe2e21f9..0296ba4cfa 100644
--- a/test/staging/sm/class/methDefn.js
+++ b/test/staging/sm/class/methDefn.js
@@ -11,14 +11,9 @@ esid: pending
 
 // Function definitions.
 function syntaxError (script) {
-    try {
+    assert.throws(SyntaxError, function() {
         Function(script);
-    } catch (e) {
-        if (e instanceof SyntaxError) {
-            return;
-        }
-    }
-    throw new Error('Expected syntax error: ' + script);
+    });
 }
 
 
diff --git a/test/staging/sm/class/methDefnGen.js b/test/staging/sm/class/methDefnGen.js
index a194ba7062..c9f8d47c23 100644
--- a/test/staging/sm/class/methDefnGen.js
+++ b/test/staging/sm/class/methDefnGen.js
@@ -11,14 +11,9 @@ esid: pending
 
 // Function definitions.
 function syntaxError (script) {
-    try {
+    assert.throws(SyntaxError, function() {
         Function(script);
-    } catch (e) {
-        if (e instanceof SyntaxError) {
-            return;
-        }
-    }
-    throw new Error('Expected syntax error: ' + script);
+    });
 }
 
 
diff --git a/test/staging/sm/expressions/binary-literals.js b/test/staging/sm/expressions/binary-literals.js
index a97db65523..25ece45bd2 100644
--- a/test/staging/sm/expressions/binary-literals.js
+++ b/test/staging/sm/expressions/binary-literals.js
@@ -19,17 +19,9 @@ for (var i = 0; i < 2; i++)
   {
     chars.forEach(function(v)
     {
-      try
-      {
+      assert.throws(SyntaxError, function() {
         eval('0' + v + i);
-        throw "didn't throw";
-      }
-      catch (e)
-      {
-        assert.sameValue(e instanceof SyntaxError, true,
-                 "no syntax error evaluating 0" + v + i + ", " +
-                 "got " + e);
-      }
+      }, "no syntax error evaluating 0" + v + i);
     });
     continue;
   }
@@ -40,17 +32,9 @@ for (var i = 0; i < 2; i++)
     {
       chars.forEach(function(v)
       {
-        try
-        {
+        assert.throws(SyntaxError, function() {
           eval('0' + v + i + j);
-          throw "didn't throw";
-        }
-        catch (e)
-        {
-          assert.sameValue(e instanceof SyntaxError, true,
-                   "no syntax error evaluating 0" + v + i + j + ", " +
-                   "got " + e);
-        }
+        }, "no syntax error evaluating 0" + v + i + j);
       });
       continue;
     }
@@ -61,17 +45,9 @@ for (var i = 0; i < 2; i++)
       {
         chars.forEach(function(v)
         {
-          try
-          {
+          assert.throws(SyntaxError, function() {
             eval('0' + v + i + j + k);
-            throw "didn't throw";
-          }
-          catch (e)
-          {
-            assert.sameValue(e instanceof SyntaxError, true,
-                     "no syntax error evaluating 0" + v + i + j + k + ", " +
-                     "got " + e);
-          }
+          }, "no syntax error evaluating 0" + v + i + j + k);
         });
         continue;
       }
@@ -86,14 +62,9 @@ for (var i = 0; i < 2; i++)
 
 chars.forEach(function(v)
 {
-  try
-  {
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof SyntaxError, true,
-             "no syntax error evaluating 0" + v + ", got " + e);
-  }
+  assert.throws(SyntaxError, function() {
+    eval('0' + v);
+  }, "no syntax error evaluating 0" + v);
 });
 
 // Off-by-one check: '/' immediately precedes '0'.
diff --git a/test/staging/sm/expressions/delete-name-parenthesized-early-error-strict-mode.js b/test/staging/sm/expressions/delete-name-parenthesized-early-error-strict-mode.js
index a5a99ce6d7..4346d3e1c4 100644
--- a/test/staging/sm/expressions/delete-name-parenthesized-early-error-strict-mode.js
+++ b/test/staging/sm/expressions/delete-name-parenthesized-early-error-strict-mode.js
@@ -13,35 +13,12 @@ esid: pending
 
 function checkSyntaxError(code)
 {
-  function helper(maker)
-  {
-    var earlyError = false;
-    try
-    {
-      var f = maker(code);
-
-      var error = "no early error, created a function with code <" + code + ">";
-      try
-      {
-        f();
-        error += ", and the function can be called without error";
-      }
-      catch (e)
-      {
-        error +=", and calling the function throws " + e;
-      }
-
-      throw new Error(error);
-    }
-    catch (e)
-    {
-      assert.sameValue(e instanceof SyntaxError, true,
-               "expected syntax error, got " + e);
-    }
-  }
-
-  helper(Function);
-  helper(eval);
+  assert.throws(SyntaxError, function() {
+    Function(code);
+  });
+  assert.throws(SyntaxError, function() {
+    (1, eval)(code); // indirect eval
+  });
 }
 
 checkSyntaxError("function f() { 'use strict'; delete escape; } f();");
diff --git a/test/staging/sm/expressions/destructuring-pattern-parenthesized.js b/test/staging/sm/expressions/destructuring-pattern-parenthesized.js
index cec92af72a..57017214cb 100644
--- a/test/staging/sm/expressions/destructuring-pattern-parenthesized.js
+++ b/test/staging/sm/expressions/destructuring-pattern-parenthesized.js
@@ -14,51 +14,27 @@ esid: pending
 // Don't pollute the top-level script with eval references.
 var savedEval = this[String.fromCharCode(101, 118, 97, 108)];
 
-function checkError(code, nonstrictErr, strictErr)
+function checkError(code)
 {
-  function helper(exec, prefix, err)
+  function helper(exec, prefix)
   {
     var fullCode = prefix + code;
-    try
-    {
-      var f = exec(fullCode);
-
-      var error =
-        "no early error, parsed code <" + fullCode + "> using " + exec.name;
-      if (typeof f === "function")
-      {
-        try
-        {
-          f();
-          error += ", and the function can be called without error";
-        }
-        catch (e)
-        {
-          error +=", and calling the function throws " + e;
-        }
-      }
-
-      throw new Error(error);
-    }
-    catch (e)
-    {
-      assert.sameValue(e instanceof err, true,
-               "expected " + err.name + ", got " + e + " " +
-               "for code <" + fullCode + "> when parsed using " + exec.name);
-    }
+    assert.throws(SyntaxError, function() {
+      exec(fullCode);
+    });
   }
 
-  helper(Function, "", nonstrictErr);
-  helper(Function, "'use strict'; ", strictErr);
-  helper(savedEval, "", nonstrictErr);
-  helper(savedEval, "'use strict'; ", strictErr);
+  helper(Function, "");
+  helper(Function, "'use strict'; ");
+  helper(savedEval, "");
+  helper(savedEval, "'use strict'; ");
 }
 
 // Parenthesized destructuring patterns don't trigger grammar refinement, so we
 // get the usual SyntaxError for an invalid assignment target, per
 // 12.14.1 second bullet.
-checkError("var a, b; ([a, b]) = [1, 2];", SyntaxError, SyntaxError);
-checkError("var a, b; ({a, b}) = { a: 1, b: 2 };", SyntaxError, SyntaxError);
+checkError("var a, b; ([a, b]) = [1, 2];");
+checkError("var a, b; ({a, b}) = { a: 1, b: 2 };");
 
 // *Nested* parenthesized destructuring patterns, on the other hand, do trigger
 // grammar refinement.  But subtargets in a destructuring pattern must be
@@ -68,11 +44,11 @@ checkError("var a, b; ({a, b}) = { a: 1, b: 2 };", SyntaxError, SyntaxError);
 // destructuring in an expression, |(a = 3)| is forbidden).  Parenthesized
 // object/array patterns are neither.  And so 12.14.5.1 third bullet requires an
 // early SyntaxError.
-checkError("var a, b; ({ a: ({ b: b }) } = { a: { b: 42 } });", SyntaxError, SyntaxError);
-checkError("var a, b; ({ a: { b: (b = 7) } } = { a: {} });", SyntaxError, SyntaxError);
-checkError("var a, b; ({ a: ([b]) } = { a: [42] });", SyntaxError, SyntaxError);
-checkError("var a, b; [(a = 5)] = [1];", SyntaxError, SyntaxError);
-checkError("var a, b; ({ a: (b = 7)} = { b: 1 });", SyntaxError, SyntaxError);
+checkError("var a, b; ({ a: ({ b: b }) } = { a: { b: 42 } });");
+checkError("var a, b; ({ a: { b: (b = 7) } } = { a: {} });");
+checkError("var a, b; ({ a: ([b]) } = { a: [42] });");
+checkError("var a, b; [(a = 5)] = [1];");
+checkError("var a, b; ({ a: (b = 7)} = { b: 1 });");
 
 Function("var a, b; [(a), b] = [1, 2];")();
 Function("var a, b; [(a) = 5, b] = [1, 2];")();
@@ -110,18 +86,18 @@ if (classesEnabled())
 
 // As noted above, when the assignment element has an initializer, the
 // assignment element must not be parenthesized.
-checkError("var a, b; [(repair.man = 17)] = [1];", SyntaxError, SyntaxError);
-checkError("var a, b; [(demolition['man'] = 'motel')] = [1, 2];", SyntaxError, SyntaxError);
-checkError("var a, b; [(demolition['man' + {}] = 'motel')] = [1];", SyntaxError, SyntaxError); // evade constant-folding
+checkError("var a, b; [(repair.man = 17)] = [1];");
+checkError("var a, b; [(demolition['man'] = 'motel')] = [1, 2];");
+checkError("var a, b; [(demolition['man' + {}] = 'motel')] = [1];"); // evade constant-folding
 if (classesEnabled())
 {
-  checkError("var a, b; var obj = { x() { [(super.man = 5)] = [1]; } };", SyntaxError, SyntaxError);
-  checkError("var a, b; var obj = { x() { [(super[8] = 'motel')] = [1]; } };", SyntaxError, SyntaxError);
-  checkError("var a, b; var obj = { x() { [(super[8 + {}] = 'motel')] = [1]; } };", SyntaxError, SyntaxError); // evade constant-folding
+  checkError("var a, b; var obj = { x() { [(super.man = 5)] = [1]; } };");
+  checkError("var a, b; var obj = { x() { [(super[8] = 'motel')] = [1]; } };");
+  checkError("var a, b; var obj = { x() { [(super[8 + {}] = 'motel')] = [1]; } };"); // evade constant-folding
 }
 
-checkError("var a, b; [f() = 'ohai', b] = [1, 2];", SyntaxError, SyntaxError);
-checkError("var a, b; [(f()) = 'kthxbai', b] = [1, 2];", SyntaxError, SyntaxError);
+checkError("var a, b; [f() = 'ohai', b] = [1, 2];");
+checkError("var a, b; [(f()) = 'kthxbai', b] = [1, 2];");
 
 Function("var a, b; ({ a: (a), b} = { a: 1, b: 2 });")();
 Function("var a, b; ({ a: (a) = 5, b} = { a: 1, b: 2 });")();
diff --git a/test/staging/sm/expressions/named-accessor-function.js b/test/staging/sm/expressions/named-accessor-function.js
index e6fd2a56a3..806f591f46 100644
--- a/test/staging/sm/expressions/named-accessor-function.js
+++ b/test/staging/sm/expressions/named-accessor-function.js
@@ -19,33 +19,11 @@ for (var i = 0, sz = BAD_CODE.length; i < sz; i++)
 {
   var code = BAD_CODE[i];
 
-  var err = "no exception";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval(code);
-  }
-  catch (e)
-  {
-    err = e;
-  }
-  if (!(err instanceof SyntaxError))
-  {
-    assert.sameValue(true, false,
-             "bad or no exception thrown for eval(" + code + "): " + err);
-  }
+  }, "bad or no exception thrown for eval(" + code + ")");
 
-  err = "no exception";
-  try
-  {
-    new Function(code);
-  }
-  catch (e)
-  {
-    err = e;
-  }
-  if (!(err instanceof SyntaxError))
-  {
-    assert.sameValue(true, false,
-             "bad or no exception thrown for Function(" + code + "): " + err);
-  }
+  assert.throws(SyntaxError, function() {
+    Function(code);
+  }, "bad or no exception thrown for Function(" + code + ")");
 }
diff --git a/test/staging/sm/expressions/nullish-coalescing.js b/test/staging/sm/expressions/nullish-coalescing.js
index 1cda3d8ed9..7e14628adc 100644
--- a/test/staging/sm/expressions/nullish-coalescing.js
+++ b/test/staging/sm/expressions/nullish-coalescing.js
@@ -24,15 +24,9 @@ function shouldNotThrow(script) {
 }
 
 function shouldThrowSyntaxError(script) {
-  let error;
-  try {
+  assert.throws(SyntaxError, function() {
     eval(script);
-  } catch (e) {
-    error = e;
-  }
-
-  if (!(error instanceof SyntaxError))
-    throw new Error('Expected SyntaxError!');
+  });
 }
 
 function testBasicCases() {
diff --git a/test/staging/sm/expressions/object-literal-accessor-arguments.js b/test/staging/sm/expressions/object-literal-accessor-arguments.js
index ee847c6994..cd0273ab1a 100644
--- a/test/staging/sm/expressions/object-literal-accessor-arguments.js
+++ b/test/staging/sm/expressions/object-literal-accessor-arguments.js
@@ -13,16 +13,9 @@ esid: pending
 
 function expectSyntaxError(s)
 {
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval(s);
-    throw new Error("no error thrown");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof SyntaxError, true,
-             "expected syntax error parsing '" + s + "', got: " + e);
-  }
+  }, "expected syntax error parsing '" + s + "'");
 }
 
 expectSyntaxError("({ get x(a) { } })");
diff --git a/test/staging/sm/expressions/octal-literals.js b/test/staging/sm/expressions/octal-literals.js
index d847db96e0..c7bcade4cd 100644
--- a/test/staging/sm/expressions/octal-literals.js
+++ b/test/staging/sm/expressions/octal-literals.js
@@ -19,17 +19,9 @@ for (var i = 0; i < 8; i++)
   {
     chars.forEach(function(v)
     {
-      try
-      {
+      assert.throws(SyntaxError, function() {
         eval('0' + v + i);
-        throw "didn't throw";
-      }
-      catch (e)
-      {
-        assert.sameValue(e instanceof SyntaxError, true,
-                 "no syntax error evaluating 0" + v + i + ", " +
-                 "got " + e);
-      }
+      }, "syntax error evaluating 0" + v + i);
     });
     continue;
   }
@@ -40,17 +32,9 @@ for (var i = 0; i < 8; i++)
     {
       chars.forEach(function(v)
       {
-        try
-        {
+        assert.throws(SyntaxError, function() {
           eval('0' + v + i + j);
-          throw "didn't throw";
-        }
-        catch (e)
-        {
-          assert.sameValue(e instanceof SyntaxError, true,
-                   "no syntax error evaluating 0" + v + i + j + ", " +
-                   "got " + e);
-        }
+        }, "syntax error evaluating 0" + v + i + j);
       });
       continue;
     }
@@ -61,17 +45,9 @@ for (var i = 0; i < 8; i++)
       {
         chars.forEach(function(v)
         {
-          try
-          {
+          assert.throws(SyntaxError, function() {
             eval('0' + v + i + j + k);
-            throw "didn't throw";
-          }
-          catch (e)
-          {
-            assert.sameValue(e instanceof SyntaxError, true,
-                     "no syntax error evaluating 0" + v + i + j + k + ", " +
-                     "got " + e);
-          }
+          }, "no syntax error evaluating 0" + v + i + j + k);
         });
         continue;
       }
diff --git a/test/staging/sm/expressions/string-literal-escape-sequences.js b/test/staging/sm/expressions/string-literal-escape-sequences.js
index 52152e1d73..eabb21802d 100644
--- a/test/staging/sm/expressions/string-literal-escape-sequences.js
+++ b/test/staging/sm/expressions/string-literal-escape-sequences.js
@@ -13,15 +13,9 @@ esid: pending
 
 function expectSyntaxError(str)
 {
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval(str);
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof SyntaxError, true,
-             "no syntax error evaluating " + str);
-  }
+  }, "syntax error evaluating " + str);
 }
 
 expectSyntaxError('"\\x"');
diff --git a/test/staging/sm/extensions/ArrayBuffer-slice-arguments-detaching.js b/test/staging/sm/extensions/ArrayBuffer-slice-arguments-detaching.js
index 74842ab7ed..aa47eae28f 100644
--- a/test/staging/sm/extensions/ArrayBuffer-slice-arguments-detaching.js
+++ b/test/staging/sm/extensions/ArrayBuffer-slice-arguments-detaching.js
@@ -25,16 +25,9 @@ function testStart()
       }
     };
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ab.slice(start);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
+  }, "start weirdness should have thrown");
   assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
 }
 testStart();
@@ -53,16 +46,9 @@ function testEnd()
       }
     };
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ab.slice(0x800, end);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "byteLength weirdness should have thrown");
+  }, "byteLength weirdness should have thrown");
   assert.sameValue(ab.byteLength, 0, "detaching should work for byteLength weirdness");
 }
 testEnd();
diff --git a/test/staging/sm/extensions/DataView-construct-arguments-detaching.js b/test/staging/sm/extensions/DataView-construct-arguments-detaching.js
index bd28b3e85e..7c62eec4a8 100644
--- a/test/staging/sm/extensions/DataView-construct-arguments-detaching.js
+++ b/test/staging/sm/extensions/DataView-construct-arguments-detaching.js
@@ -25,16 +25,9 @@ function testByteOffset()
       }
     };
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     new DataView(ab, start);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "byteOffset weirdness should have thrown");
+  }, "byteOffset weirdness should have thrown");
   assert.sameValue(ab.byteLength, 0, "detaching should work for byteOffset weirdness");
 }
 testByteOffset();
@@ -53,16 +46,9 @@ function testByteLength()
       }
     };
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     new DataView(ab, 0x800, len);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "byteLength weirdness should have thrown");
+  }, "byteLength weirdness should have thrown");
   assert.sameValue(ab.byteLength, 0, "detaching should work for byteLength weirdness");
 }
 testByteLength();
diff --git a/test/staging/sm/extensions/DataView-set-arguments-detaching.js b/test/staging/sm/extensions/DataView-set-arguments-detaching.js
index c624e3d9b7..60d538186d 100644
--- a/test/staging/sm/extensions/DataView-set-arguments-detaching.js
+++ b/test/staging/sm/extensions/DataView-set-arguments-detaching.js
@@ -27,16 +27,9 @@ function testIndex()
       }
     };
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     dv.setUint8(start, 0x42);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "should have thrown");
+  });
   assert.sameValue(ab.byteLength, 0, "should have been detached correctly");
 }
 testIndex();
@@ -57,16 +50,9 @@ function testValue()
       }
     };
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     dv.setUint8(0xFFFFF, value);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "should have thrown");
+  });
   assert.sameValue(ab.byteLength, 0, "should have been detached correctly");
 }
 testValue();
diff --git a/test/staging/sm/extensions/TypedArray-subarray-arguments-detaching.js b/test/staging/sm/extensions/TypedArray-subarray-arguments-detaching.js
index 208246d4ab..e1d64808c9 100644
--- a/test/staging/sm/extensions/TypedArray-subarray-arguments-detaching.js
+++ b/test/staging/sm/extensions/TypedArray-subarray-arguments-detaching.js
@@ -26,16 +26,9 @@ function testBegin()
 
   var ta = new Uint8Array(ab);
 
-  var ok = false;
-  try
-  {
-    ta.subarray(begin);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
+  assert.throws(TypeError, function() {
+    ta.subarray(begin)
+  }, "start weirdness should have thrown");
   assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
 }
 testBegin();
@@ -55,16 +48,9 @@ function testBeginWithEnd()
 
   var ta = new Uint8Array(ab);
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ta.subarray(begin, 0x1000);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
+  }, "start weirdness should have thrown");
   assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
 }
 testBeginWithEnd();
@@ -84,16 +70,9 @@ function testEnd()
 
   var ta = new Uint8Array(ab);
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ta.subarray(0x800, end);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
-  assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
+  }, "end weirdness should have thrown");
+  assert.sameValue(ab.byteLength, 0, "detaching should work for end weirdness");
 }
 testEnd();
diff --git a/test/staging/sm/extensions/arguments-property-access-in-function.js b/test/staging/sm/extensions/arguments-property-access-in-function.js
index 015e3f2d8a..146dc8bd42 100644
--- a/test/staging/sm/extensions/arguments-property-access-in-function.js
+++ b/test/staging/sm/extensions/arguments-property-access-in-function.js
@@ -30,17 +30,9 @@ var sobj =
     {
      "use strict";
 
-      try
-      {
-        var args = sobj.test.arguments;
-        throw new Error("access to arguments property of strict mode " +
-                        "function didn't throw");
-      }
-      catch (e)
-      {
-        assert.sameValue(e instanceof TypeError, true,
-                 "should have thrown TypeError, instead got: " + e);
-      }
+      assert.throws(TypeError, function() {
+        sobj.test.arguments;
+      }, "access to arguments property of strict mode function");
     }
   };
 sobj.test(5, undefined);
diff --git a/test/staging/sm/extensions/dataview.js b/test/staging/sm/extensions/dataview.js
index 5b423ed95a..af1836dbc5 100644
--- a/test/staging/sm/extensions/dataview.js
+++ b/test/staging/sm/extensions/dataview.js
@@ -12,23 +12,8 @@ esid: pending
 ---*/
 
 function test(sharedMem) {
-    function die(message, uplevel) {
-        throw new Error(message);
-    }
-
     function checkThrow(fun, type) {
-        var thrown = false;
-        try {
-            fun();
-        } catch (x) {
-            thrown = x;
-        }
-
-        if (!thrown) {
-            die('no exception thrown, expected ' + type.name, 2);
-        } else if (!(thrown instanceof type)) {
-            die('expected ' + type.name + ', got ' + thrown, 2);
-        }
+        assert.throws(type, fun);
     }
 
     function bufferize(u8array) {
diff --git a/test/staging/sm/extensions/destructure-accessor.js b/test/staging/sm/extensions/destructure-accessor.js
index 599feeb37d..b31babfc29 100644
--- a/test/staging/sm/extensions/destructure-accessor.js
+++ b/test/staging/sm/extensions/destructure-accessor.js
@@ -27,16 +27,9 @@ function expectOk(s)
 
 function expectSyntaxError(s)
 {
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval(s);
-    throw new Error("no error thrown");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof SyntaxError, true,
-             "expected syntax error parsing '" + s + "', got: " + e);
-  }
+  }, "expected syntax error parsing '" + s + "'");
 }
 
 expectSyntaxError("({ get x([]) { } })");
diff --git a/test/staging/sm/extensions/es5ish-defineGetter-defineSetter.js b/test/staging/sm/extensions/es5ish-defineGetter-defineSetter.js
index 692af31995..3658f63052 100644
--- a/test/staging/sm/extensions/es5ish-defineGetter-defineSetter.js
+++ b/test/staging/sm/extensions/es5ish-defineGetter-defineSetter.js
@@ -67,20 +67,6 @@ function check(obj, prop, expected)
   checkField("configurable", desc, expected);
 }
 
-function expectTypeError(f)
-{
-  try
-  {
-    f();
-    throw new Error("no error thrown");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "wrong error thrown: got " + e + ", not a TypeError");
-  }
-}
-
 /**************
  * BEGIN TEST *
  **************/
@@ -137,8 +123,8 @@ gsobj.__defineSetter__("baz", s3);
 check(gsobj, "baz", { get: g3, set: s3, enumerable: true, configurable: true });
 
 Object.defineProperty(gsobj, "baz", { configurable: false });
-expectTypeError(function() { gsobj.__defineSetter__("baz", s2); });
-expectTypeError(function() { gsobj.__defineSetter__("baz", s3); });
+assert.throws(TypeError, function() { gsobj.__defineSetter__("baz", s2); });
+assert.throws(TypeError, function() { gsobj.__defineSetter__("baz", s3); });
 check(gsobj, "baz", { get: g3, set: s3, enumerable: true, configurable: false });
 
 /******************************************************************************/
@@ -169,8 +155,8 @@ sgobj.__defineSetter__("baz", s4);
 check(sgobj, "baz", { get: g4, set: s4, enumerable: true, configurable: true });
 
 Object.defineProperty(sgobj, "baz", { configurable: false });
-expectTypeError(function() { sgobj.__defineGetter__("baz", g3); });
-expectTypeError(function() { sgobj.__defineSetter__("baz", s4); });
+assert.throws(TypeError, function() { sgobj.__defineGetter__("baz", g3); });
+assert.throws(TypeError, function() { sgobj.__defineSetter__("baz", s4); });
 check(sgobj, "baz", { get: g4, set: s4, enumerable: true, configurable: false });
 
 /******************************************************************************/
@@ -231,7 +217,7 @@ check(gncover, "moo", { value: 17, writable: true, enumerable: true, configurabl
 Object.defineProperty(gncover, "moo", { configurable: false });
 check(gncover, "moo", { value: 17, writable: true, enumerable: true, configurable: false });
 
-expectTypeError(function() { gncover.__defineGetter__("moo", g7); });
+assert.throws(TypeError, function() { gncover.__defineGetter__("moo", g7); });
 check(gncover, "moo", { value: 17, writable: true, enumerable: true, configurable: false });
 
 /******************************************************************************/
@@ -244,7 +230,7 @@ check(sncover, "moo", { value: 17, writable: true, enumerable: true, configurabl
 Object.defineProperty(sncover, "moo", { configurable: false });
 check(sncover, "moo", { value: 17, writable: true, enumerable: true, configurable: false });
 
-expectTypeError(function() { sncover.__defineSetter__("moo", s7); });
+assert.throws(TypeError, function() { sncover.__defineSetter__("moo", s7); });
 check(sncover, "moo", { value: 17, writable: true, enumerable: true, configurable: false });
 
 /******************************************************************************/
@@ -257,7 +243,7 @@ check(gncwover, "fwoosh", { value: 17, writable: true, enumerable: true, configu
 Object.defineProperty(gncwover, "fwoosh", { writable: false, configurable: false });
 check(gncwover, "fwoosh", { value: 17, writable: false, enumerable: true, configurable: false });
 
-expectTypeError(function() { gncwover.__defineGetter__("fwoosh", g7); });
+assert.throws(TypeError, function() { gncwover.__defineGetter__("fwoosh", g7); });
 check(gncwover, "fwoosh", { value: 17, writable: false, enumerable: true, configurable: false });
 
 /******************************************************************************/
@@ -270,5 +256,5 @@ check(sncwover, "fwoosh", { value: 17, writable: true, enumerable: true, configu
 Object.defineProperty(sncwover, "fwoosh", { writable: false, configurable: false });
 check(sncwover, "fwoosh", { value: 17, writable: false, enumerable: true, configurable: false });
 
-expectTypeError(function() { sncwover.__defineSetter__("fwoosh", s7); });
+assert.throws(TypeError, function() { sncwover.__defineSetter__("fwoosh", s7); });
 check(sncwover, "fwoosh", { value: 17, writable: false, enumerable: true, configurable: false });
diff --git a/test/staging/sm/extensions/expression-closure-syntax.js b/test/staging/sm/extensions/expression-closure-syntax.js
index a8c0af4ec7..e3a399b3a8 100644
--- a/test/staging/sm/extensions/expression-closure-syntax.js
+++ b/test/staging/sm/extensions/expression-closure-syntax.js
@@ -16,19 +16,9 @@ esid: pending
   {
     function testOne(replacement)
     {
-      var x, rv;
-      try
-      {
-        rv = eval(code.replace("@@@", replacement));
-      }
-      catch (e)
-      {
-        assert.sameValue(e instanceof SyntaxError, true,
-                 "should have thrown a SyntaxError, instead got: " + e);
-        return;
-      }
-
-      assert.sameValue(true, false, "should have thrown, instead returned " + rv);
+      assert.throws(SyntaxError, function() {
+        eval(code.replace("@@@", replacement));
+      });
     }
 
     testOne("function");
diff --git a/test/staging/sm/extensions/extension-methods-reject-null-undefined-this.js b/test/staging/sm/extensions/extension-methods-reject-null-undefined-this.js
index 06fe50f278..982511f41d 100644
--- a/test/staging/sm/extensions/extension-methods-reject-null-undefined-this.js
+++ b/test/staging/sm/extensions/extension-methods-reject-null-undefined-this.js
@@ -39,44 +39,23 @@ function testMethod(Class, className, method)
     var badThis = badThisValues[i];
 
     expr = className + ".prototype." + method + ".call(" + badThis + ")";
-    try
-    {
+    assert.throws(TypeError, function() {
       Class.prototype[method].call(badThis);
-      throw new Error(expr + " didn't throw a TypeError");
-    }
-    catch (e)
-    {
-      assert.sameValue(e instanceof TypeError, true,
-               "wrong error for " + expr + ", instead threw " + e);
-    }
+    }, "wrong error for " + expr);
 
     expr = className + ".prototype." + method + ".apply(" + badThis + ")";
-    try
-    {
+    assert.throws(TypeError, function() {
       Class.prototype[method].apply(badThis);
-      throw new Error(expr + " didn't throw a TypeError");
-    }
-    catch (e)
-    {
-      assert.sameValue(e instanceof TypeError, true,
-               "wrong error for " + expr + ", instead threw " + e);
-    }
+    }, "wrong error for " + expr);
   }
 
   // ..and for good measure..
 
   expr = "(0, " + className + ".prototype." + method + ")()"
-  try
-  {
+  assert.throws(TypeError, function() {
     // comma operator to call GetValue() on the method and de-Reference it
     (0, Class.prototype[method])();
-    throw new Error(expr + " didn't throw a TypeError");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "wrong error for " + expr + ", instead threw " + e);
-  }
+  }, "wrong error for " + expr);
 }
 
 for (var className in ClassToMethodMap)
diff --git a/test/staging/sm/extensions/new-cross-compartment.js b/test/staging/sm/extensions/new-cross-compartment.js
index d32a7d1cae..3a20c4acac 100644
--- a/test/staging/sm/extensions/new-cross-compartment.js
+++ b/test/staging/sm/extensions/new-cross-compartment.js
@@ -17,15 +17,9 @@ var otherStr = new g.String("foo");
 assert.sameValue(otherStr instanceof g.String, true);
 assert.sameValue(otherStr.valueOf(), "foo");
 
-try
-{
+// NOTE: not |g.TypeError|, because |new| itself throws because
+//       |!IsConstructor(constructor)|.
+assert.throws(TypeError, function() {
   var constructor = g.parseInt;
   new constructor();
-  throw new Error("no error thrown");
-}
-catch (e)
-{
-  // NOTE: not |g.TypeError|, because |new| itself throws because
-  //       |!IsConstructor(constructor)|.
-  assert.sameValue(e instanceof TypeError, true);
-}
+});
diff --git a/test/staging/sm/extensions/proxy-array-target-length-definition.js b/test/staging/sm/extensions/proxy-array-target-length-definition.js
index d1e3d5472a..210a2b7371 100644
--- a/test/staging/sm/extensions/proxy-array-target-length-definition.js
+++ b/test/staging/sm/extensions/proxy-array-target-length-definition.js
@@ -14,21 +14,11 @@ esid: pending
 var arr = [];
 var p = new Proxy(arr, {});
 
-function assertThrowsTypeError(f)
-{
-    try {
-        f();
-        assert.sameValue(false, true, "Must have thrown");
-    } catch (e) {
-        assert.sameValue(e instanceof TypeError, true, "Must have thrown TypeError");
-    }
-}
-
 // Redefining non-configurable length should throw a TypeError
-assertThrowsTypeError(function () { Object.defineProperty(p, "length", { value: 17, configurable: true }); });
+assert.throws(TypeError, function () { Object.defineProperty(p, "length", { value: 17, configurable: true }); });
 
 // Same here.
-assertThrowsTypeError(function () { Object.defineProperty(p, "length", { value: 42, enumerable: true }); });
+assert.throws(TypeError, function () { Object.defineProperty(p, "length", { value: 42, enumerable: true }); });
 
 // Check the property went unchanged.
 var pd = Object.getOwnPropertyDescriptor(p, "length");
diff --git a/test/staging/sm/extensions/regress-469625-01.js b/test/staging/sm/extensions/regress-469625-01.js
index 2cdddc68cd..ef3a85ed6a 100644
--- a/test/staging/sm/extensions/regress-469625-01.js
+++ b/test/staging/sm/extensions/regress-469625-01.js
@@ -11,27 +11,8 @@ description: |
 esid: pending
 ---*/
 
-var actual = '';
-var expect = '';
+Array.prototype.__proto__ = function () { return 3; };
 
-//-----------------------------------------------------------------------------
-test();
-//-----------------------------------------------------------------------------
-
-function test()
-{
-  expect = 'TypeError: [].__proto__ is not a function';
-
-  Array.prototype.__proto__ = function () { return 3; };
-
-  try
-  {
-    [].__proto__();
-  }
-  catch(ex)
-  {
-    actual = ex + '';
-  }
-
-  assert.sameValue(expect, actual);
-}
+assert.throws(TypeError, function() {
+  [].__proto__();
+});
diff --git a/test/staging/sm/extensions/regress-bug629723.js b/test/staging/sm/extensions/regress-bug629723.js
index 994ec88a95..3414dc8666 100644
--- a/test/staging/sm/extensions/regress-bug629723.js
+++ b/test/staging/sm/extensions/regress-bug629723.js
@@ -8,19 +8,10 @@ description: |
   pending
 esid: pending
 ---*/
+
 function f(foo) {
     "use strict";
     foo.bar;
 }
 
-var actual;
-try {
-    f();
-    actual = "no error";
-} catch (x) {
-    actual = (x instanceof TypeError) ? "type error" : "some other error";
-    actual += (/use strict/.test(x)) ? " with directive" : " without directive";
-}
-
-assert.sameValue("type error without directive", actual,
-              "decompiled expressions in error messages should not include directive prologues");
+assert.throws(TypeError, f);
diff --git a/test/staging/sm/extensions/typedarray-copyWithin-arguments-detaching.js b/test/staging/sm/extensions/typedarray-copyWithin-arguments-detaching.js
index 5168b6fd00..9ca6ddf071 100644
--- a/test/staging/sm/extensions/typedarray-copyWithin-arguments-detaching.js
+++ b/test/staging/sm/extensions/typedarray-copyWithin-arguments-detaching.js
@@ -26,17 +26,10 @@ function testBegin()
 
   var ta = new Uint8Array(ab);
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ta.copyWithin(0, begin, 0x1000);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
-  assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
+  }, "begin weirdness should have thrown");
+  assert.sameValue(ab.byteLength, 0, "detaching should work for begin weirdness");
 }
 testBegin();
 
@@ -55,17 +48,10 @@ function testEnd()
 
   var ta = new Uint8Array(ab);
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ta.copyWithin(0, 0x800, end);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
-  assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
+  }, "end weirdness should have thrown");
+  assert.sameValue(ab.byteLength, 0, "detaching should work for end weirdness");
 }
 testEnd();
 
@@ -84,16 +70,9 @@ function testDest()
 
   var ta = new Uint8Array(ab);
 
-  var ok = false;
-  try
-  {
+  assert.throws(TypeError, function() {
     ta.copyWithin(dest, 0x800, 0x1000);
-  }
-  catch (e)
-  {
-    ok = true;
-  }
-  assert.sameValue(ok, true, "start weirdness should have thrown");
-  assert.sameValue(ab.byteLength, 0, "detaching should work for start weirdness");
+  }, "dest weirdness should have thrown");
+  assert.sameValue(ab.byteLength, 0, "detaching should work for dest weirdness");
 }
 testDest();
diff --git a/test/staging/sm/extensions/weakmap.js b/test/staging/sm/extensions/weakmap.js
index 913e3dfd43..5ad1b48777 100644
--- a/test/staging/sm/extensions/weakmap.js
+++ b/test/staging/sm/extensions/weakmap.js
@@ -15,46 +15,12 @@ test();
 
 function test()
 {
-    var TestPassCount = 0;
-    var TestFailCount = 0;
-    var TestTodoCount = 0;
-
-    var TODO = 1;
-
-    function check(fun, todo) {
-        var thrown = null;
-        var success = false;
-        try {
-            success = fun();
-        } catch (x) {
-            thrown = x;
-        }
-
-        if (thrown)
-            success = false;
-
-        if (todo) {
-            TestTodoCount++;
-
-            return;
-        }
-
-        if (success) {
-            TestPassCount++;
-        } else {
-            TestFailCount++;
-        }
+    function check(fun) {
+        assert.sameValue(fun(), true);
     }
 
-    function checkThrows(fun, todo) {
-        let thrown = false;
-        try {
-            fun();
-        } catch (x) {
-            thrown = true;
-        }
-
-        check(() => thrown, todo);
+    function checkThrows(fun) {
+        assert.throws(TypeError, fun);
     }
 
     var key = {};
@@ -93,6 +59,4 @@ function test()
     check(() => map.get(key) == undefined);
 
     checkThrows(() => map.set("non-object key", value));
-
-    assert.sameValue(0, TestFailCount, "weak map tests");
 }
diff --git a/test/staging/sm/generators/syntax.js b/test/staging/sm/generators/syntax.js
index 631bd06554..4731dd1f3c 100644
--- a/test/staging/sm/generators/syntax.js
+++ b/test/staging/sm/generators/syntax.js
@@ -17,17 +17,10 @@ esid: pending
 function assertSyntaxError(str) {
     var msg;
     var evil = eval;
-    try {
+    assert.throws(SyntaxError, function() {
         // Non-direct eval.
         evil(str);
-    } catch (exc) {
-        if (exc instanceof SyntaxError)
-            return;
-        msg = "Assertion failed: expected SyntaxError, got " + exc;
-    }
-    if (msg === undefined)
-        msg = "Assertion failed: expected SyntaxError, but no exception thrown";
-    throw new Error(msg + " - " + str);
+    });
 }
 
 // Yield statements.
diff --git a/test/staging/sm/global/bug660612.js b/test/staging/sm/global/bug660612.js
index 7d37f04262..c0de147249 100644
--- a/test/staging/sm/global/bug660612.js
+++ b/test/staging/sm/global/bug660612.js
@@ -8,9 +8,7 @@ description: |
   pending
 esid: pending
 ---*/
-try {
-    decodeURIComponent('%ED%A0%80');
-    assert.sameValue(true, false, "expected an URIError");
-} catch (e) {
-  assert.sameValue(e instanceof URIError, true);
-}
+
+assert.throws(URIError, function() {
+  decodeURIComponent('%ED%A0%80');
+});
diff --git a/test/staging/sm/lexical-environment/block-scoped-functions-annex-b-label.js b/test/staging/sm/lexical-environment/block-scoped-functions-annex-b-label.js
index 22df8691fb..7a8d270a17 100644
--- a/test/staging/sm/lexical-environment/block-scoped-functions-annex-b-label.js
+++ b/test/staging/sm/lexical-environment/block-scoped-functions-annex-b-label.js
@@ -8,32 +8,23 @@ description: |
   pending
 esid: pending
 ---*/
-function expectSyntaxError(str) {
-  var threwSyntaxError;
-  try {
-    eval(str);
-  } catch (e) {
-    threwSyntaxError = e instanceof SyntaxError;
-  }
-  assert.sameValue(threwSyntaxError, true);
 
-  try {
+function expectSyntaxError(str) {
+  assert.throws(SyntaxError, function() {
+    eval(str);
+  });
+
+  assert.throws(SyntaxError, function() {
     eval('"use strict";' + str);
-  } catch (e) {
-    threwSyntaxError = e instanceof SyntaxError;
-  }
-  assert.sameValue(threwSyntaxError, true);
+  });
 }
 
 function expectSloppyPass(str) {
   eval(str);
 
-  try {
+  assert.throws(SyntaxError, function() {
     eval('"use strict";' + str);
-  } catch (e) {
-    threwSyntaxError = e instanceof SyntaxError;
-  }
-  assert.sameValue(threwSyntaxError, true);
+  });
 }
 
 expectSloppyPass(`l: function f1() {}`);
@@ -49,4 +40,3 @@ expectSyntaxError(`while (0) l: function f5() {}`);
 expectSyntaxError(`for (;;) l: function f6() {}`);
 expectSloppyPass(`switch (1) { case 1: l: function f7() {} }`);
 expectSloppyPass(`switch (1) { case 1: assert.sameValue(f8(), 'f8'); case 2: l: function f8() { return 'f8'; } } assert.sameValue(f8(), 'f8');`);
-
diff --git a/test/staging/sm/lexical-environment/block-scoped-functions-deprecated-redecl.js b/test/staging/sm/lexical-environment/block-scoped-functions-deprecated-redecl.js
index 6b1d76d9ff..ada1357a95 100644
--- a/test/staging/sm/lexical-environment/block-scoped-functions-deprecated-redecl.js
+++ b/test/staging/sm/lexical-environment/block-scoped-functions-deprecated-redecl.js
@@ -8,6 +8,7 @@ description: |
   pending
 esid: pending
 ---*/
+
 {
   assert.sameValue(f(), 4);
   function f() { return 3; }
@@ -46,41 +47,27 @@ function test() {
 
 test();
 
-var log = '';
-
-try {
-  // Strict mode still cannot redeclare.
+// Strict mode still cannot redeclare.
+assert.throws(SyntaxError, function() {
   eval(`"use strict";
   {
     function f() { }
     function f() { }
   }`);
-} catch (e) {
-  assert.sameValue(e instanceof SyntaxError, true);
-  log += 'e';
-}
+});
 
-try {
-  // Redeclaring an explicitly 'let'-declared binding doesn't work.
+// Redeclaring an explicitly 'let'-declared binding doesn't work.
+assert.throws(SyntaxError, function() {
   eval(`{
     let x = 42;
     function x() {}
   }`);
-} catch (e) {
-  assert.sameValue(e instanceof SyntaxError, true);
-  log += 'e';
-}
+});
 
-try {
-  // Redeclaring an explicitly 'const'-declared binding doesn't work.
+// Redeclaring an explicitly 'const'-declared binding doesn't work.
+assert.throws(SyntaxError, function() {
   eval(`{
     const x = 42;
     function x() {}
   }`);
-} catch (e) {
-  assert.sameValue(e instanceof SyntaxError, true);
-  log += 'e';
-}
-
-assert.sameValue(log, 'eee');
-
+});
diff --git a/test/staging/sm/lexical-environment/block-scoped-functions-hoisted-tdz.js b/test/staging/sm/lexical-environment/block-scoped-functions-hoisted-tdz.js
index 60e8cb31c1..d64daef0ee 100644
--- a/test/staging/sm/lexical-environment/block-scoped-functions-hoisted-tdz.js
+++ b/test/staging/sm/lexical-environment/block-scoped-functions-hoisted-tdz.js
@@ -8,31 +8,19 @@ description: |
   pending
 esid: pending
 ---*/
-var log = "";
-try {
-  (function() {
-    {
-      let y = f();
-      function f() { y; }
-    }
-  })()
-} catch (e) {
-  log += e instanceof ReferenceError;
-}
 
-try {
-  function f() {
-    switch (1) {
-      case 0:
-        let x;
-      case 1:
-        (function() { x; })();
-    }
+assert.throws(ReferenceError, function() {
+  {
+    let y = f();
+    function f() { y; }
   }
-  f();
-} catch (e) {
-  log += e instanceof ReferenceError;
-}
-
-assert.sameValue(log, "truetrue");
+});
 
+assert.throws(ReferenceError, function() {
+  switch (1) {
+    case 0:
+      let x;
+    case 1:
+      (function() { x; })();
+  }
+});
diff --git a/test/staging/sm/lexical-environment/for-loop.js b/test/staging/sm/lexical-environment/for-loop.js
index d452ca19a2..17005a002e 100644
--- a/test/staging/sm/lexical-environment/for-loop.js
+++ b/test/staging/sm/lexical-environment/for-loop.js
@@ -13,16 +13,9 @@ esid: pending
 
 function isError(code, type)
 {
-  try
-  {
+  assert.throws(type, function() {
     Function(code);
-    throw new Error("didn't throw");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof type, true,
-             "unexpected error for `" + code + "`: got " + e);
-  }
+  });
 }
 
 function isOK(code)
diff --git a/test/staging/sm/misc/builtin-methods-reject-null-undefined-this.js b/test/staging/sm/misc/builtin-methods-reject-null-undefined-this.js
index 6713320dc5..0c8a9a2b3a 100644
--- a/test/staging/sm/misc/builtin-methods-reject-null-undefined-this.js
+++ b/test/staging/sm/misc/builtin-methods-reject-null-undefined-this.js
@@ -92,44 +92,24 @@ function testMethod(Class, className, method)
     var badThis = badThisValues[i];
 
     expr = className + ".prototype." + method + ".call(" + badThis + ")";
-    try
-    {
+    assert.throws(TypeError, function() {
       Class.prototype[method].call(badThis);
-      throw new Error(expr + " didn't throw a TypeError");
-    }
-    catch (e)
-    {
-      assert.sameValue(e instanceof TypeError, true,
-               "wrong error for " + expr + ", instead threw " + e);
-    }
+    }, "wrong error for " + expr);
+
 
     expr = className + ".prototype." + method + ".apply(" + badThis + ")";
-    try
-    {
+    assert.throws(TypeError, function() {
       Class.prototype[method].apply(badThis);
-      throw new Error(expr + " didn't throw a TypeError");
-    }
-    catch (e)
-    {
-      assert.sameValue(e instanceof TypeError, true,
-               "wrong error for " + expr + ", instead threw " + e);
-    }
+    }, "wrong error for " + expr);
   }
 
   // ..and for good measure..
 
-  expr = "(0, " + className + ".prototype." + method + ")()"
-  try
-  {
+  expr = "(0, " + className + ".prototype." + method + ")()";
+  assert.throws(TypeError, function() {
     // comma operator to call GetValue() on the method and de-Reference it
     (0, Class.prototype[method])();
-    throw new Error(expr + " didn't throw a TypeError");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "wrong error for " + expr + ", instead threw " + e);
-  }
+  }, "wrong error for " + expr);
 }
 
 for (var className in ClassToMethodMap)
diff --git a/test/staging/sm/misc/future-reserved-words.js b/test/staging/sm/misc/future-reserved-words.js
index ac26e1d017..45052ef699 100644
--- a/test/staging/sm/misc/future-reserved-words.js
+++ b/test/staging/sm/misc/future-reserved-words.js
@@ -14,7 +14,7 @@ esid: pending
 var futureReservedWords =
   [
    "class",
-   // "const", // Mozilla extension enabled even for versionless code
+   "const",
    "enum",
    "export",
    "extends",
@@ -26,459 +26,97 @@ var strictFutureReservedWords =
   [
    "implements",
    "interface",
-   "let", // enabled: this file doesn't execute as JS1.7
+   "let",
    "package",
    "private",
    "protected",
    "public",
    "static",
-   "yield", // enabled: this file doesn't execute as JS1.7
+   "yield",
   ];
 
-function testWord(word, expectNormal, expectStrict)
-{
-  var actual, status;
+function testNormalAndStrict(word, code, message) {
+  if (strictFutureReservedWords.includes(word)) {
+    eval(code);
+  } else {
+    assert(futureReservedWords.includes(word));
+    assert.throws(SyntaxError, function() {
+      eval(code);
+    }, word + ": normal " + message);
+  }
 
+  assert.throws(SyntaxError, function() {
+    eval("'use strict'; " + code);
+  }, word + ": strict " + message);
+}
+
+function testWord(word) {
   // USE AS LHS FOR ASSIGNMENT
-
-  actual = "";
-  status = word + ": normal assignment";
-  try
-  {
-    eval(word + " = 'foo';");
-    actual = "no error";
-  }
-  catch(e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict assignment";
-  try
-  {
-    eval("'use strict'; " + word + " = 'foo';");
-    actual = "no error";
-  }
-  catch(e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  testNormalAndStrict(word, word + " = 'foo';", "assignment");
 
   // USE AS DESTRUCTURING SHORTHAND
-
-  actual = "";
-  status = word + ": destructuring shorthand";
-  try
-  {
-    eval("({ " + word + " } = 'foo');");
-    actual = "no error";
-  }
-  catch(e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict destructuring shorthand";
-  try
-  {
-    eval("'use strict'; ({ " + word + " } = 'foo');");
-    actual = "no error";
-  }
-  catch(e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  testNormalAndStrict(word, "({ " + word + " } = 'foo');", "destructuring shorthand");
 
   // USE IN VARIABLE DECLARATION
-
-  actual = "";
-  status = word + ": normal var";
-  try
-  {
-    eval("var " + word + ";");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict var";
-  try
-  {
-    eval("'use strict'; var " + word + ";");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  testNormalAndStrict(word, "var " + word + ";", "var");
 
   // USE IN FOR-IN VARIABLE DECLARATION
-
-  actual = "";
-  status = word + ": normal for-in var";
-  try
-  {
-    eval("for (var " + word + " in {});");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict for-in var";
-  try
-  {
-    eval("'use strict'; for (var " + word + " in {});");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  testNormalAndStrict(word, "for (var " + word + " in {});", "for-in var");
 
   // USE AS CATCH IDENTIFIER
-
-  actual = "";
-  status = word + ": normal var";
-  try
-  {
-    eval("try { } catch (" + word + ") { }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict var";
-  try
-  {
-    eval("'use strict'; try { } catch (" + word + ") { }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  testNormalAndStrict(word, "try { } catch (" + word + ") { }", "catch var");
 
   // USE AS LABEL
-
-  actual = "";
-  status = word + ": normal label";
-  try
-  {
-    eval(word + ": while (false);");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict label";
-  try
-  {
-    eval("'use strict'; " + word + ": while (false);");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  testNormalAndStrict(word, word + ": while (false);", "label");
 
   // USE AS ARGUMENT NAME IN FUNCTION DECLARATION
+  testNormalAndStrict(word, "function foo(" + word + ") { }", "function argument");
 
-  actual = "";
-  status = word + ": normal function argument";
-  try
-  {
-    eval("function foo(" + word + ") { }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict function argument";
-  try
-  {
-    eval("'use strict'; function foo(" + word + ") { }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
-
-  actual = "";
-  status = word + ": function argument retroactively strict";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval("function foo(" + word + ") { 'use strict'; }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  }, word + ": function argument retroactively strict");
 
   // USE AS ARGUMENT NAME IN FUNCTION EXPRESSION
+  testNormalAndStrict(word, "var s = (function foo(" + word + ") { });", "function expression argument");
 
-  actual = "";
-  status = word + ": normal function expression argument";
-  try
-  {
-    eval("var s = (function foo(" + word + ") { });");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict function expression argument";
-  try
-  {
-    eval("'use strict'; var s = (function foo(" + word + ") { });");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
-
-  actual = "";
-  status = word + ": function expression argument retroactively strict";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval("var s = (function foo(" + word + ") { 'use strict'; });");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  }, word + ": function expression argument retroactively strict");
 
   // USE AS ARGUMENT NAME WITH FUNCTION CONSTRUCTOR
-
-  actual = "";
-  status = word + ": argument with normal Function";
-  try
-  {
+  if (strictFutureReservedWords.includes(word)) {
     Function(word, "return 17");
-    actual = "no error";
+  } else {
+    assert.throws(SyntaxError, function() {
+      Function(word, "return 17");
+    }, word + ": argument with normal Function");
   }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
 
-  actual = "";
-  status = word + ": argument with strict Function";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     Function(word, "'use strict'; return 17");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  }, word + ": argument with strict Function");
 
   // USE AS ARGUMENT NAME IN PROPERTY SETTER
+  testNormalAndStrict(word, "var o = { set x(" + word + ") { } };", "property setter argument");
 
-  actual = "";
-  status = word + ": normal property setter argument";
-  try
-  {
-    eval("var o = { set x(" + word + ") { } };");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict property setter argument";
-  try
-  {
-    eval("'use strict'; var o = { set x(" + word + ") { } };");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
-
-  actual = "";
-  status = word + ": property setter argument retroactively strict";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval("var o = { set x(" + word + ") { 'use strict'; } };");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  }, word + ": property setter argument retroactively strict");
 
   // USE AS FUNCTION NAME IN FUNCTION DECLARATION
+  testNormalAndStrict(word, "function " + word + "() { }", "function name");
 
-  actual = "";
-  status = word + ": normal function name";
-  try
-  {
-    eval("function " + word + "() { }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict function name";
-  try
-  {
-    eval("'use strict'; function " + word + "() { }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
-
-  actual = "";
-  status = word + ": function name retroactively strict";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval("function " + word + "() { 'use strict'; }");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  }, word + ": function name retroactively strict");
 
   // USE AS FUNCTION NAME IN FUNCTION EXPRESSION
+  testNormalAndStrict(word, "var s = (function " + word + "() { });", "function expression name");
 
-  actual = "";
-  status = word + ": normal function expression name";
-  try
-  {
-    eval("var s = (function " + word + "() { });");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectNormal, status);
-
-  actual = "";
-  status = word + ": strict function expression name";
-  try
-  {
-    eval("'use strict'; var s = (function " + word + "() { });");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
-
-  actual = "";
-  status = word + ": function expression name retroactively strict";
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval("var s = (function " + word + "() { 'use strict'; });");
-    actual = "no error";
-  }
-  catch (e)
-  {
-    actual = e.name;
-    status +=  ", " + e.name + ": " + e.message + " ";
-  }
-  assert.sameValue(actual, expectStrict, status);
+  }, word + ": function expression name retroactively strict");
 }
 
-function testFutureReservedWord(word)
-{
-  testWord(word, "SyntaxError", "SyntaxError");
-}
-
-function testStrictFutureReservedWord(word)
-{
-  testWord(word, "no error", "SyntaxError");
-}
-
-futureReservedWords.forEach(testFutureReservedWord);
-strictFutureReservedWords.forEach(testStrictFutureReservedWord);
+futureReservedWords.forEach(testWord);
+strictFutureReservedWords.forEach(testWord);
diff --git a/test/staging/sm/misc/global-numeric-properties.js b/test/staging/sm/misc/global-numeric-properties.js
index 6ce3ca9985..3f38822719 100644
--- a/test/staging/sm/misc/global-numeric-properties.js
+++ b/test/staging/sm/misc/global-numeric-properties.js
@@ -11,7 +11,7 @@ description: |
 esid: pending
 ---*/
 
-var desc, old, error;
+var desc, old;
 var global = this;
 
 var names = ["NaN", "Infinity", "undefined"];
@@ -29,22 +29,8 @@ for (var i = 0; i < names.length; i++)
   global[name] = 17;
   assert.sameValue(global[name], old, name + " changed on setting?");
 
-  error = "before";
-  try
-  {
-    throw new TypeError("SpiderMonkey doesn't currently implement " +
-                        "strict-mode throwing when setting a readonly " +
-                        "property, not running this bit of test for now; " +
-                        "see bug 537873");
-
-    (function() { "use strict"; global[name] = 42; error = "didn't throw"; })();
-  }
-  catch (e)
-  {
-    if (e instanceof TypeError)
-      error = "typeerror";
-    else
-      error = "bad exception: " + e;
-  }
-  assert.sameValue(error, "typeerror", "wrong strict mode error setting " + name);
+  assert.throws(TypeError, function() {
+    "use strict";
+    global[name] = 42;
+  }, "wrong strict mode error setting " + name);
 }
diff --git a/test/staging/sm/misc/new-with-non-constructor.js b/test/staging/sm/misc/new-with-non-constructor.js
index 574f78f18b..20a78c8992 100644
--- a/test/staging/sm/misc/new-with-non-constructor.js
+++ b/test/staging/sm/misc/new-with-non-constructor.js
@@ -10,14 +10,11 @@ description: |
   pending
 esid: pending
 ---*/
+
 function checkConstruct(thing) {
-    try {
-        new thing();
-        assert.sameValue(0, 1, "not reached " + thing);
-    } catch (e) {
-        assert.sameValue(e.message.includes(" is not a constructor") ||
-                 e.message === "Function.prototype.toString called on incompatible object", true);
-    }
+  assert.throws(TypeError, function() {
+    new thing();
+  });
 }
 
 var re = /aaa/
@@ -34,4 +31,3 @@ checkConstruct(proxiedFunctionPrototype);
 
 var proxiedBuiltin = new Proxy(parseInt, {});
 checkConstruct(proxiedBuiltin);
-
diff --git a/test/staging/sm/misc/syntax-error-end-of-for-head-part.js b/test/staging/sm/misc/syntax-error-end-of-for-head-part.js
index 0eee14a67f..3fbf89888d 100644
--- a/test/staging/sm/misc/syntax-error-end-of-for-head-part.js
+++ b/test/staging/sm/misc/syntax-error-end-of-for-head-part.js
@@ -13,16 +13,9 @@ esid: pending
 
 function checkSyntaxError(str)
 {
-  try
-  {
-    var f = Function("for(w in\\");
-    throw new Error("didn't throw, returned " + f);
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof SyntaxError, true,
-             "expected SyntaxError, got " + e);
-  }
+  assert.throws(SyntaxError, function() {
+    Function(str);
+  });
 }
 
 checkSyntaxError("for(var w in \\");
diff --git a/test/staging/sm/misc/unicode-escaped-keyword.js b/test/staging/sm/misc/unicode-escaped-keyword.js
index fa4e5848bf..07a5aca0a3 100644
--- a/test/staging/sm/misc/unicode-escaped-keyword.js
+++ b/test/staging/sm/misc/unicode-escaped-keyword.js
@@ -10,18 +10,14 @@ description: |
   pending
 esid: pending
 ---*/
+
 function throws(code) {
-    var type;
-    try {
-        eval(code);
-    } catch (ex) {
-        type = ex.name;
-    }
-    assert.sameValue(type, 'SyntaxError');
+  assert.throws(SyntaxError, function() {
+    eval(code);
+  });
 }
 
 var s = '\\u0073';
 throws('var thi' + s);
 throws('switch (' + s + 'witch) {}')
 throws('var ' + s + 'witch');
-
diff --git a/test/staging/sm/misc/unicode-identifier-1d17.js b/test/staging/sm/misc/unicode-identifier-1d17.js
index c286d7209f..2e9fcb396f 100644
--- a/test/staging/sm/misc/unicode-identifier-1d17.js
+++ b/test/staging/sm/misc/unicode-identifier-1d17.js
@@ -10,12 +10,7 @@ description: |
   pending
 esid: pending
 ---*/
-var o = {}
-try {
-    eval('o.\\u1d17 = 42;');
-}
-catch (e) {
-    assert.sameValue('should not fail', true);
-}
-assert.sameValue(o['\u1d17'], 42);
 
+var o = {}
+eval('o.\\u1d17 = 42;');
+assert.sameValue(o['\u1d17'], 42);
diff --git a/test/staging/sm/misc/unicode-identifier-82f1.js b/test/staging/sm/misc/unicode-identifier-82f1.js
index 709d0afa1d..483d2b4cbb 100644
--- a/test/staging/sm/misc/unicode-identifier-82f1.js
+++ b/test/staging/sm/misc/unicode-identifier-82f1.js
@@ -10,12 +10,7 @@ description: |
   pending
 esid: pending
 ---*/
-var o = {}
-try {
-    eval('o.\\u82f1 = 42;');
-}
-catch (e) {
-    assert.sameValue('should not fail', true);
-}
-assert.sameValue(o['\u82f1'], 42);
 
+var o = {}
+eval('o.\\u82f1 = 42;');
+assert.sameValue(o['\u82f1'], 42);
diff --git a/test/staging/sm/object/15.2.3.5-01.js b/test/staging/sm/object/15.2.3.5-01.js
index 3c0d65652a..f1e2c495ad 100644
--- a/test/staging/sm/object/15.2.3.5-01.js
+++ b/test/staging/sm/object/15.2.3.5-01.js
@@ -42,11 +42,8 @@ assert.sameValue(Object.getOwnPropertyDescriptor(o, "baz"), undefined);
 assert.sameValue(o.baz, 12);
 assert.sameValue(o.hasOwnProperty("baz"), false);
 
-try {
-  var actual =
-    Object.create(Object.create({},
-                                { boom: { get: function() { return "base"; }}}),
-                  { boom: { get: function() { return "overridden"; }}}).boom
-} catch (e) {
-}
+var actual =
+  Object.create(Object.create({},
+                              { boom: { get: function() { return "base"; }}}),
+                { boom: { get: function() { return "overridden"; }}}).boom
 assert.sameValue(actual, "overridden");
diff --git a/test/staging/sm/object/15.2.3.7-01.js b/test/staging/sm/object/15.2.3.7-01.js
index 88aa00ff6d..0a55e723f9 100644
--- a/test/staging/sm/object/15.2.3.7-01.js
+++ b/test/staging/sm/object/15.2.3.7-01.js
@@ -41,20 +41,10 @@ props =
     c: { value: NaN, enumerable: false, configurable: true, writable: true },
     b: { value: 44 }
   };
-var error = "before";
-try
-{
+
+assert.throws(TypeError, function() {
   Object.defineProperties(o, props);
-  error = "no exception thrown";
-}
-catch (e)
-{
-  if (e instanceof TypeError)
-    error = "typeerror";
-  else
-    error = "bad exception: " + e;
-}
-assert.sameValue(error, "typeerror", "didn't throw or threw wrongly");
+});
 assert.sameValue("c" in o, true, "new property added");
 assert.sameValue(o.b, 42, "old property value preserved");
 
@@ -84,46 +74,14 @@ assert.sameValue("bar" in o, false, "bar is not an enumerable own property");
 Object.defineProperties(o, "");
 assert.sameValue("quux" in o, false, "quux is not an enumerable own property");
 
-error = "before";
-try
-{
+assert.throws(TypeError, function() {
   Object.defineProperties(o, "1");
-}
-catch (e)
-{
-  if (e instanceof TypeError)
-    error = "typeerror";
-  else
-    error = "bad exception: " + e;
-}
-assert.sameValue(error, "typeerror",
-         "should throw on Properties == '1' due to '1'[0] not being a " +
-         "property descriptor");
+}, "should throw on Properties == '1' due to '1'[0] not being a property descriptor");
 
-error = "before";
-try
-{
+assert.throws(TypeError, function() {
   Object.defineProperties(o, null);
-}
-catch (e)
-{
-  if (e instanceof TypeError)
-    error = "typeerror";
-  else
-    error = "bad exception: " + e;
-}
-assert.sameValue(error, "typeerror", "should throw on Properties == null");
+}, "should throw on Properties == null");
 
-error = "before";
-try
-{
+assert.throws(TypeError, function() {
   Object.defineProperties(o, undefined);
-}
-catch (e)
-{
-  if (e instanceof TypeError)
-    error = "typeerror";
-  else
-    error = "bad exception: " + e;
-}
-assert.sameValue(error, "typeerror", "should throw on Properties == undefined");
+}, "should throw on Properties == undefined");
diff --git a/test/staging/sm/object/extensibility-01.js b/test/staging/sm/object/extensibility-01.js
index 90234224ff..931bd4ca3f 100644
--- a/test/staging/sm/object/extensibility-01.js
+++ b/test/staging/sm/object/extensibility-01.js
@@ -11,56 +11,31 @@ description: |
 esid: pending
 ---*/
 
-function trySetProperty(o, p, v, strict)
+function tryStrictSetProperty(o, p, v)
 {
-  function strictSetProperty()
-  {
+  assert.sameValue(Object.prototype.hasOwnProperty.call(o, p), false);
+  assert.throws(TypeError, function() {
     "use strict";
     o[p] = v;
-  }
-
-  function setProperty()
-  {
-    o[p] = v;
-  }
+  });
+}
 
+function trySetProperty(o, p, v)
+{
   assert.sameValue(Object.prototype.hasOwnProperty.call(o, p), false);
 
-  try
-  {
-    if (strict)
-      strictSetProperty();
-    else
-      setProperty();
-    if (o[p] === v)
-      return "set";
-    if (p in o)
-      return "set-converted";
-    return "swallowed";
-  }
-  catch (e)
-  {
-    return "throw";
-  }
+  o[p] = v;
+
+  assert.notSameValue(o[p], v);
+  assert.sameValue(p in o, false);
 }
 
 function tryDefineProperty(o, p, v)
 {
   assert.sameValue(Object.prototype.hasOwnProperty.call(o, p), false);
-
-  try
-  {
+  assert.throws(TypeError, function() {
     Object.defineProperty(o, p, { value: v });
-    if (o[p] === v)
-      return "set";
-    if (p in o)
-      return "set-converted";
-    return "swallowed";
-  }
-  catch (e)
-  {
-    return "throw";
-  }
+  });
 }
 
 assert.sameValue(typeof Object.preventExtensions, "function");
@@ -81,12 +56,7 @@ for (var i = 0, sz = objs.length; i < sz; i++)
 
   assert.sameValue(Object.isExtensible(o), false, "object " + i + " is extensible?");
 
-  assert.sameValue(trySetProperty(o, "baz", 17, true), "throw",
-           "unexpected behavior for strict-mode property-addition to " +
-           "object " + i);
-  assert.sameValue(trySetProperty(o, "baz", 17, false), "swallowed",
-           "unexpected behavior for property-addition to object " + i);
-
-  assert.sameValue(tryDefineProperty(o, "baz", 17), "throw",
-           "unexpected behavior for new property definition on object " + i);
+  tryStrictSetProperty(o, "baz", 17);
+  trySetProperty(o, "baz", 17);
+  tryDefineProperty(o, "baz", 17);
 }
diff --git a/test/staging/sm/object/isPrototypeOf.js b/test/staging/sm/object/isPrototypeOf.js
index 57094e7690..8a585318a0 100644
--- a/test/staging/sm/object/isPrototypeOf.js
+++ b/test/staging/sm/object/isPrototypeOf.js
@@ -11,20 +11,6 @@ description: |
 esid: pending
 ---*/
 
-function expectThrowTypeError(fun)
-{
-  try
-  {
-    var r = fun();
-    throw new Error("didn't throw TypeError, returned " + r);
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "didn't throw TypeError, got: " + e);
-  }
-}
-
 var isPrototypeOf = Object.prototype.isPrototypeOf;
 
 /*
@@ -48,12 +34,12 @@ assert.sameValue(isPrototypeOf(null), false);
  *    argument.
  */
 var protoGlobal = Object.create(this);
-expectThrowTypeError(function() { isPrototypeOf.call(null, {}); });
-expectThrowTypeError(function() { isPrototypeOf.call(undefined, {}); });
-expectThrowTypeError(function() { isPrototypeOf({}); });
-expectThrowTypeError(function() { isPrototypeOf.call(null, protoGlobal); });
-expectThrowTypeError(function() { isPrototypeOf.call(undefined, protoGlobal); });
-expectThrowTypeError(function() { isPrototypeOf(protoGlobal); });
+assert.throws(TypeError, function() { isPrototypeOf.call(null, {}); });
+assert.throws(TypeError, function() { isPrototypeOf.call(undefined, {}); });
+assert.throws(TypeError, function() { isPrototypeOf({}); });
+assert.throws(TypeError, function() { isPrototypeOf.call(null, protoGlobal); });
+assert.throws(TypeError, function() { isPrototypeOf.call(undefined, protoGlobal); });
+assert.throws(TypeError, function() { isPrototypeOf(protoGlobal); });
 
 
 /*
diff --git a/test/staging/sm/object/propertyIsEnumerable.js b/test/staging/sm/object/propertyIsEnumerable.js
index 342c3065c5..b309349374 100644
--- a/test/staging/sm/object/propertyIsEnumerable.js
+++ b/test/staging/sm/object/propertyIsEnumerable.js
@@ -11,25 +11,6 @@ description: |
 esid: pending
 ---*/
 
-function expectThrowError(errorCtor, fun)
-{
-  try
-  {
-    var r = fun();
-    throw "didn't throw TypeError, returned " + r;
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof errorCtor, true,
-             "didn't throw " + errorCtor.prototype.name + ", got: " + e);
-  }
-}
-
-function expectThrowTypeError(fun)
-{
-  expectThrowError(TypeError, fun);
-}
-
 function withToString(fun)
 {
   return { toString: fun };
@@ -45,106 +26,106 @@ var propertyIsEnumerable = Object.prototype.propertyIsEnumerable;
 /*
  * 1. Let P be ToString(V).
  */
-expectThrowError(ReferenceError, function()
+assert.throws(ReferenceError, function()
 {
   propertyIsEnumerable(withToString(function() { fahslkjdfhlkjdsl; }));
 });
-expectThrowError(ReferenceError, function()
+assert.throws(ReferenceError, function()
 {
   propertyIsEnumerable.call(null, withToString(function() { fahslkjdfhlkjdsl; }));
 });
-expectThrowError(ReferenceError, function()
+assert.throws(ReferenceError, function()
 {
   propertyIsEnumerable.call(undefined, withToString(function() { fahslkjdfhlkjdsl; }));
 });
 
-expectThrowError(ReferenceError, function()
+assert.throws(ReferenceError, function()
 {
   propertyIsEnumerable(withValueOf(function() { fahslkjdfhlkjdsl; }));
 });
-expectThrowError(ReferenceError, function()
+assert.throws(ReferenceError, function()
 {
   propertyIsEnumerable.call(null, withValueOf(function() { fahslkjdfhlkjdsl; }));
 });
-expectThrowError(ReferenceError, function()
+assert.throws(ReferenceError, function()
 {
   propertyIsEnumerable.call(undefined, withValueOf(function() { fahslkjdfhlkjdsl; }));
 });
 
-expectThrowError(SyntaxError, function()
+assert.throws(SyntaxError, function()
 {
   propertyIsEnumerable(withToString(function() { eval("}"); }));
 });
-expectThrowError(SyntaxError, function()
+assert.throws(SyntaxError, function()
 {
   propertyIsEnumerable.call(null, withToString(function() { eval("}"); }));
 });
-expectThrowError(SyntaxError, function()
+assert.throws(SyntaxError, function()
 {
   propertyIsEnumerable.call(undefined, withToString(function() { eval("}"); }));
 });
 
-expectThrowError(SyntaxError, function()
+assert.throws(SyntaxError, function()
 {
   propertyIsEnumerable(withValueOf(function() { eval("}"); }));
 });
-expectThrowError(SyntaxError, function()
+assert.throws(SyntaxError, function()
 {
   propertyIsEnumerable.call(null, withValueOf(function() { eval("}"); }));
 });
-expectThrowError(SyntaxError, function()
+assert.throws(SyntaxError, function()
 {
   propertyIsEnumerable.call(undefined, withValueOf(function() { eval("}"); }));
 });
 
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable(withToString(function() { [].length = -1; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(null, withToString(function() { [].length = -1; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(undefined, withToString(function() { [].length = -1; }));
 });
 
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable(withValueOf(function() { [].length = -1; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(null, withValueOf(function() { [].length = -1; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(undefined, withValueOf(function() { [].length = -1; }));
 });
 
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable(withToString(function() { [].length = 0.7; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(null, withToString(function() { [].length = 0.7; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(undefined, withToString(function() { [].length = 0.7; }));
 });
 
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable(withValueOf(function() { [].length = 0.7; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(null, withValueOf(function() { [].length = 0.7; }));
 });
-expectThrowError(RangeError, function()
+assert.throws(RangeError, function()
 {
   propertyIsEnumerable.call(undefined, withValueOf(function() { [].length = 0.7; }));
 });
@@ -153,19 +134,19 @@ expectThrowError(RangeError, function()
  * 2. Let O be the result of calling ToObject passing the this value as the
  *    argument.
  */
-expectThrowTypeError(function() { propertyIsEnumerable("s"); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(null, "s"); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(undefined, "s"); });
-expectThrowTypeError(function() { propertyIsEnumerable(true); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(null, true); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(undefined, true); });
-expectThrowTypeError(function() { propertyIsEnumerable(NaN); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(null, NaN); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(undefined, NaN); });
+assert.throws(TypeError, function() { propertyIsEnumerable("s"); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(null, "s"); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(undefined, "s"); });
+assert.throws(TypeError, function() { propertyIsEnumerable(true); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(null, true); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(undefined, true); });
+assert.throws(TypeError, function() { propertyIsEnumerable(NaN); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(null, NaN); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(undefined, NaN); });
 
-expectThrowTypeError(function() { propertyIsEnumerable({}); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(null, {}); });
-expectThrowTypeError(function() { propertyIsEnumerable.call(undefined, {}); });
+assert.throws(TypeError, function() { propertyIsEnumerable({}); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(null, {}); });
+assert.throws(TypeError, function() { propertyIsEnumerable.call(undefined, {}); });
 
 /*
  * 3. Let desc be the result of calling the [[GetOwnProperty]] internal method
@@ -180,7 +161,7 @@ assert.sameValue(propertyIsEnumerable.call(true, "toString"), false);
 assert.sameValue(propertyIsEnumerable.call({}, "__proto__"), false);
 
 assert.sameValue(propertyIsEnumerable.call(Object, "getOwnPropertyDescriptor"), false);
-assert.sameValue(propertyIsEnumerable.call(this, "expectThrowTypeError"), true);
+assert.sameValue(propertyIsEnumerable.call(this, "withToString"), true);
 assert.sameValue(propertyIsEnumerable.call("s", "length"), false);
 assert.sameValue(propertyIsEnumerable.call("s", 0), true);
 assert.sameValue(propertyIsEnumerable.call(Number, "MAX_VALUE"), false);
diff --git a/test/staging/sm/object/toLocaleString.js b/test/staging/sm/object/toLocaleString.js
index 67fe6eaaaf..9111d57ce9 100644
--- a/test/staging/sm/object/toLocaleString.js
+++ b/test/staging/sm/object/toLocaleString.js
@@ -11,30 +11,16 @@ description: |
 esid: pending
 ---*/
 
-function expectThrowTypeError(fun)
-{
-  try
-  {
-    var r = fun();
-    throw "didn't throw TypeError, returned " + r;
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof TypeError, true,
-             "didn't throw TypeError, got: " + e);
-  }
-}
-
 var toLocaleString = Object.prototype.toLocaleString;
 
 /*
  * 1. Let O be the result of calling ToObject passing the this value as the
  *    argument.
  */
-expectThrowTypeError(function() { toLocaleString.call(null); });
-expectThrowTypeError(function() { toLocaleString.call(undefined); });
-expectThrowTypeError(function() { toLocaleString.apply(null); });
-expectThrowTypeError(function() { toLocaleString.apply(undefined); });
+assert.throws(TypeError, function() { toLocaleString.call(null); });
+assert.throws(TypeError, function() { toLocaleString.call(undefined); });
+assert.throws(TypeError, function() { toLocaleString.apply(null); });
+assert.throws(TypeError, function() { toLocaleString.apply(undefined); });
 
 
 /*
@@ -53,27 +39,27 @@ catch (e)
 
 
 /* 3. If IsCallable(toString) is false, throw a TypeError exception. */
-expectThrowTypeError(function() { toLocaleString.call({ toString: 12 }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: 0.3423423452352e9 }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: undefined }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: false }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: [] }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: {} }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: new String }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: new Number(7.7) }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: new Boolean(true) }); });
-expectThrowTypeError(function() { toLocaleString.call({ toString: JSON }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: 12 }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: 0.3423423452352e9 }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: undefined }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: false }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: [] }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: {} }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: new String }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: new Number(7.7) }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: new Boolean(true) }); });
+assert.throws(TypeError, function() { toLocaleString.call({ toString: JSON }); });
 
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: 12 }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: 0.3423423452352e9 }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: undefined }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: false }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: [] }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: {} }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: new String }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: new Number(7.7) }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: new Boolean(true) }); });
-expectThrowTypeError(function() { toLocaleString.call({ valueOf: 0, toString: JSON }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: 12 }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: 0.3423423452352e9 }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: undefined }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: false }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: [] }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: {} }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: new String }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: new Number(7.7) }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: new Boolean(true) }); });
+assert.throws(TypeError, function() { toLocaleString.call({ valueOf: 0, toString: JSON }); });
 
 
 /*
diff --git a/test/staging/sm/object/values-entries-typedarray.js b/test/staging/sm/object/values-entries-typedarray.js
index 9c211ff315..b36107b469 100644
--- a/test/staging/sm/object/values-entries-typedarray.js
+++ b/test/staging/sm/object/values-entries-typedarray.js
@@ -9,41 +9,13 @@ description: |
   pending
 esid: pending
 ---*/
+
 function assertSameEntries(actual, expected) {
     assert.sameValue(actual.length, expected.length);
     for (let i = 0; i < expected.length; ++i)
         assert.compareArray(actual[i], expected[i]);
 }
 
-function throwsTypeError(fn) {
-    try {
-        fn();
-    } catch (e) {
-        assert.sameValue(e instanceof TypeError, true);
-        return true;
-    }
-    return false;
-}
-
-// Non-standard: Accessing elements of detached array buffers should throw, but
-// this is currently not implemented.
-const ACCESS_ON_DETACHED_ARRAY_BUFFER_THROWS = (() => {
-    let ta = new Int32Array(10);
-    $262.detachArrayBuffer(ta.buffer);
-    let throws = throwsTypeError(() => ta[0]);
-    // Ensure [[Get]] and [[GetOwnProperty]] return consistent results.
-    assert.sameValue(throwsTypeError(() => Object.getOwnPropertyDescriptor(ta, 0)), throws);
-    return throws;
-})();
-
-function maybeThrowOnDetached(fn, returnValue) {
-    if (ACCESS_ON_DETACHED_ARRAY_BUFFER_THROWS) {
-        assert.throws(TypeError, fn);
-        return returnValue;
-    }
-    return fn();
-}
-
 // Ensure Object.keys/values/entries work correctly on typed arrays.
 for (let len of [0, 1, 10]) {
     let array = new Array(len).fill(1);
@@ -55,8 +27,7 @@ for (let len of [0, 1, 10]) {
 
     $262.detachArrayBuffer(ta.buffer);
 
-    assert.compareArray(maybeThrowOnDetached(() => Object.keys(ta), []), []);
-    assert.compareArray(maybeThrowOnDetached(() => Object.values(ta), []), []);
-    assertSameEntries(maybeThrowOnDetached(() => Object.entries(ta), []), []);
+    assert.compareArray(Object.keys(ta), []);
+    assert.compareArray(Object.values(ta), []);
+    assertSameEntries(Object.entries(ta), []);
 }
-
diff --git a/test/staging/sm/regress/regress-410852.js b/test/staging/sm/regress/regress-410852.js
index 0a65d50986..a3dcb40317 100644
--- a/test/staging/sm/regress/regress-410852.js
+++ b/test/staging/sm/regress/regress-410852.js
@@ -11,17 +11,6 @@ description: |
 esid: pending
 ---*/
 
-test();
-
-function test()
-{
-  try
-  {
-    eval('function(){if(t)');
-  }
-  catch(ex)
-  {
-    assert.sameValue(ex instanceof SyntaxError, true, "wrong error: " + ex);
-  }
-
-}
+assert.throws(SyntaxError, function() {
+  eval('function(){if(t)');
+});
diff --git a/test/staging/sm/regress/regress-499524.js b/test/staging/sm/regress/regress-499524.js
index 341d753a49..f7b4d6ac6f 100644
--- a/test/staging/sm/regress/regress-499524.js
+++ b/test/staging/sm/regress/regress-499524.js
@@ -10,15 +10,15 @@ description: |
   pending
 esid: pending
 ---*/
-function isSyntaxError(code) {
-  try {
+
+function throwsNoSyntaxError(code) {
+  eval(code);
+};
+
+function throwsSyntaxError(code) {
+  assert.throws(SyntaxError, function() {
     eval(code);
-    return false;
-  } catch (exception) {
-    if (SyntaxError.prototype.isPrototypeOf(exception))
-      return true;
-    throw exception;
-  };
+  });
 };
 
 /* 
@@ -27,28 +27,27 @@ function isSyntaxError(code) {
  * user has opted in to a modicum of sanity, and we forbid duplicate
  * parameter names.
  */
-assert.sameValue(isSyntaxError("function f(x,x){}"),                false);
+throwsNoSyntaxError("function f(x,x){}");
 
-assert.sameValue(isSyntaxError("function f(x,[x]){})"),             true);
-assert.sameValue(isSyntaxError("function f(x,{y:x}){})"),           true);
-assert.sameValue(isSyntaxError("function f(x,{x}){})"),             true);
+throwsSyntaxError("function f(x,[x]){})");
+throwsSyntaxError("function f(x,{y:x}){})");
+throwsSyntaxError("function f(x,{x}){})");
 
-assert.sameValue(isSyntaxError("function f([x],x){})"),             true);
-assert.sameValue(isSyntaxError("function f({y:x},x){})"),           true);
-assert.sameValue(isSyntaxError("function f({x},x){})"),             true);
+throwsSyntaxError("function f([x],x){})");
+throwsSyntaxError("function f({y:x},x){})");
+throwsSyntaxError("function f({x},x){})");
 
-assert.sameValue(isSyntaxError("function f([x,x]){}"),              true);
-assert.sameValue(isSyntaxError("function f({x,x}){}"),              true);
-assert.sameValue(isSyntaxError("function f({y:x,z:x}){}"),          true);
+throwsSyntaxError("function f([x,x]){}");
+throwsSyntaxError("function f({x,x}){}");
+throwsSyntaxError("function f({y:x,z:x}){}");
 
-assert.sameValue(isSyntaxError("function f(x,x,[y]){}"),            true);
-assert.sameValue(isSyntaxError("function f(x,x,{y}){}"),            true);
-assert.sameValue(isSyntaxError("function f([y],x,x){}"),            true);
-assert.sameValue(isSyntaxError("function f({y},x,x){}"),            true);
-
-assert.sameValue(isSyntaxError("function f(a,b,c,d,e,f,g,h,b,[y]){}"),  true);
-assert.sameValue(isSyntaxError("function f([y],a,b,c,d,e,f,g,h,a){}"),  true);
-assert.sameValue(isSyntaxError("function f([a],b,c,d,e,f,g,h,i,a){}"),  true);
-assert.sameValue(isSyntaxError("function f(a,b,c,d,e,f,g,h,i,[a]){}"),  true);
-assert.sameValue(isSyntaxError("function f(a,b,c,d,e,f,g,h,i,[a]){}"),  true);
+throwsSyntaxError("function f(x,x,[y]){}");
+throwsSyntaxError("function f(x,x,{y}){}");
+throwsSyntaxError("function f([y],x,x){}");
+throwsSyntaxError("function f({y},x,x){}");
 
+throwsSyntaxError("function f(a,b,c,d,e,f,g,h,b,[y]){}");
+throwsSyntaxError("function f([y],a,b,c,d,e,f,g,h,a){}");
+throwsSyntaxError("function f([a],b,c,d,e,f,g,h,i,a){}");
+throwsSyntaxError("function f(a,b,c,d,e,f,g,h,i,[a]){}");
+throwsSyntaxError("function f(a,b,c,d,e,f,g,h,i,[a]){}");
diff --git a/test/staging/sm/regress/regress-571014.js b/test/staging/sm/regress/regress-571014.js
index b712323fb7..acd475342a 100644
--- a/test/staging/sm/regress/regress-571014.js
+++ b/test/staging/sm/regress/regress-571014.js
@@ -14,29 +14,19 @@ var F, o;
 F = function () {};
 F.prototype = new ArrayBuffer(1);
 o = new F();
-try {
-    o.byteLength;
-} catch (ex) {
-    // o is not a platform object
-    assert.sameValue(ex instanceof TypeError, true);
-}
+assert.throws(TypeError, function() {
+  o.byteLength;
+});
 
 o = {};
 o.__proto__ = new Int32Array(1);
-try {
-    o.buffer.byteLength;
-} catch (ex) {
-    // o is not a platform object
-    assert.sameValue(ex instanceof TypeError, true);
-}
+assert.throws(TypeError, function() {
+  o.buffer.byteLength;
+});
 
 F = function () {};
 F.prototype = new Int32Array(1);
 o = new F();
-try {
-    o.slice(0, 1);
-    reportFailure("Expected an exception!");
-} catch (ex) {
-}
-
-assert.sameValue("ok", "ok", "bug 571014");
+assert.throws(TypeError, function() {
+  o.slice(0, 1);
+});
diff --git a/test/staging/sm/regress/regress-573875.js b/test/staging/sm/regress/regress-573875.js
index 401b2185e9..bb0114c19d 100644
--- a/test/staging/sm/regress/regress-573875.js
+++ b/test/staging/sm/regress/regress-573875.js
@@ -10,19 +10,12 @@ description: |
   pending
 esid: pending
 ---*/
+
 var o = {__iterator__:null, a:1, b:2, c:3}
 var expect = '__iterator__,a,b,c,';
 var actual = '';
 
-try {
-    for (var i in o)
-        actual += i + ',';
-} catch (e) {
-    actual = '' + e;
-    if (/invalid __iterator__ value/.test(actual) ||
-        /null is not a function/.test(actual)) {
-        expect = actual;
-    }
-}
+for (var i in o)
+    actual += i + ',';
 
 assert.sameValue(expect, actual, "ok");
diff --git a/test/staging/sm/regress/regress-617405-2.js b/test/staging/sm/regress/regress-617405-2.js
index 762babff45..d36e12cdb4 100644
--- a/test/staging/sm/regress/regress-617405-2.js
+++ b/test/staging/sm/regress/regress-617405-2.js
@@ -10,13 +10,12 @@ description: |
   pending
 esid: pending
 ---*/
+
 function C(){}
 C.prototype = 1;
-try {
-    Object.defineProperty(C, "prototype", {get: function() { throw 0; }});
-    actual = "no exception";
-} catch (exc) {
-    actual = exc.name;
-}
+
+assert.throws(TypeError, function() {
+  Object.defineProperty(C, "prototype", {get: function() { throw 0; }});
+});
+
 new C; // don't assert
-assert.sameValue(actual, "TypeError");
diff --git a/test/staging/sm/regress/regress-618572.js b/test/staging/sm/regress/regress-618572.js
index 2cf9b11c35..0ce12ee933 100644
--- a/test/staging/sm/regress/regress-618572.js
+++ b/test/staging/sm/regress/regress-618572.js
@@ -7,31 +7,10 @@
 flags:
   - noStrict
 description: |
-  pending
+  Do not assert when ungetting a Unicode char sequence
 esid: pending
 ---*/
-//-----------------------------------------------------------------------------
-var BUGNUMBER = 618572;
-var summary = 'Do not assert when ungetting a Unicode char sequence';
-var actual = '';
-var expect = '';
 
-//-----------------------------------------------------------------------------
-test();
-//-----------------------------------------------------------------------------
-
-function test()
-{
-  expect = 'SyntaxError';
-
-  try
-  {
-    eval("var a\\0021 = 3;");
-  }
-  catch(ex)
-  {
-    actual = ex.constructor.name;
-  }
-
-  assert.sameValue(expect, actual, summary);
-}
+assert.throws(SyntaxError, function() {
+  eval("var a\\0021 = 3;");
+});
diff --git a/test/staging/sm/regress/regress-624968.js b/test/staging/sm/regress/regress-624968.js
index 8a2dce5a70..4048c59fca 100644
--- a/test/staging/sm/regress/regress-624968.js
+++ b/test/staging/sm/regress/regress-624968.js
@@ -10,7 +10,7 @@ description: |
   pending
 esid: pending
 ---*/
-try {
-    new {prototype: TypeError.prototype};
-} catch (e) {}
 
+assert.throws(TypeError, function() {
+  new {prototype: TypeError.prototype};
+});
diff --git a/test/staging/sm/statements/arrow-function-in-for-statement-head.js b/test/staging/sm/statements/arrow-function-in-for-statement-head.js
index 36c177c337..6a3c1ca0b9 100644
--- a/test/staging/sm/statements/arrow-function-in-for-statement-head.js
+++ b/test/staging/sm/statements/arrow-function-in-for-statement-head.js
@@ -11,13 +11,6 @@ description: |
 esid: pending
 ---*/
 
-try
-{
+assert.throws(SyntaxError, function() {
   Function("for (x => 0 in 1;;) break;");
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "expected syntax error, got " + e);
-}
+});
diff --git a/test/staging/sm/statements/for-of-var-with-initializer.js b/test/staging/sm/statements/for-of-var-with-initializer.js
index f9ef77ddc8..bcaba3d3c1 100644
--- a/test/staging/sm/statements/for-of-var-with-initializer.js
+++ b/test/staging/sm/statements/for-of-var-with-initializer.js
@@ -11,13 +11,6 @@ description: |
 esid: pending
 ---*/
 
-try
-{
+assert.throws(SyntaxError, function() {
   Function("for (var x = 3 of 42);");
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "expected syntax error, got: " + e);
-}
+});
diff --git a/test/staging/sm/strict/assign-to-callee-name.js b/test/staging/sm/strict/assign-to-callee-name.js
index a8c53f0fbc..5d4bebdf44 100644
--- a/test/staging/sm/strict/assign-to-callee-name.js
+++ b/test/staging/sm/strict/assign-to-callee-name.js
@@ -12,17 +12,7 @@ esid: pending
 ---*/
 
 var f = function assignSelfStrict() { "use strict"; assignSelfStrict = 12; };
-
-try
-{
-  var r = f();
-  throw new Error("should have thrown a TypeError, returned " + r);
-}
-catch (e)
-{
-  assert.sameValue(e instanceof TypeError, true,
-           "didn't throw a TypeError: " + e);
-}
+assert.throws(TypeError, f);
 
 var assignSelf = 42;
 var f2 = function assignSelf() { assignSelf = 12; };
diff --git a/test/staging/sm/strict/directive-prologue-01.js b/test/staging/sm/strict/directive-prologue-01.js
index c48edd2a32..8bc7bfa8e1 100644
--- a/test/staging/sm/strict/directive-prologue-01.js
+++ b/test/staging/sm/strict/directive-prologue-01.js
@@ -11,51 +11,21 @@ description: |
 esid: pending
 ---*/
 
-try
-{
+assert.throws(SyntaxError, function() {
   eval(" '\\145'; 'use strict'; ");
-  throw new Error("no error thrown for eval");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "wrong error for octal-escape before strict directive in eval");
-}
+}, "wrong error for octal-escape before strict directive in eval");
 
-try
-{
+assert.throws(SyntaxError, function() {
   Function(" '\\145'; 'use strict'; ");
-  throw new Error("no error thrown for Function");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "wrong error for octal-escape before strict directive in Function");
-}
+}, "wrong error for octal-escape before strict directive in Function");
 
-try
-{
+assert.throws(SyntaxError, function() {
   eval(" function f(){ '\\145'; 'use strict'; } ");
-  throw new Error("no error thrown for eval of function");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "wrong error for octal-escape before strict directive in eval of " +
-           "function");
-}
+}, "wrong error for octal-escape before strict directive in eval of function");
 
-try
-{
+assert.throws(SyntaxError, function() {
   Function(" function f(){ '\\145'; 'use strict'; } ");
-  throw new Error("no error thrown for eval of function");
-}
-catch (e)
-{
-  assert.sameValue(e instanceof SyntaxError, true,
-           "wrong error for octal-escape before strict directive in eval of " +
-           "function");
-}
+}, "wrong error for octal-escape before strict directive in eval of function");
 
 eval("function notAnError1() { 5; '\\145'; function g() { 'use strict'; } }");
 
diff --git a/test/staging/sm/strict/rebind-eval-should-fail-in-strict-mode.js b/test/staging/sm/strict/rebind-eval-should-fail-in-strict-mode.js
index 716ec45eed..914042d65a 100644
--- a/test/staging/sm/strict/rebind-eval-should-fail-in-strict-mode.js
+++ b/test/staging/sm/strict/rebind-eval-should-fail-in-strict-mode.js
@@ -29,17 +29,10 @@ var BadSyntaxStrings = [
 ];
 
 function testString(s, i) {
-    var gotSyntaxError = -1;
-    try {
+    assert.throws(SyntaxError, function() {
         eval(s);
-    } catch(err) {
-        if (err instanceof SyntaxError)
-            gotSyntaxError = i;
-    }
-
-    assert.sameValue(gotSyntaxError, i);
+    });
 }
 
 for (var i = 0; i < BadSyntaxStrings.length; i++)
     testString(BadSyntaxStrings[i], i);
-
diff --git a/test/staging/sm/strict/unbrand-this.js b/test/staging/sm/strict/unbrand-this.js
index 793141c6bb..7041543d34 100644
--- a/test/staging/sm/strict/unbrand-this.js
+++ b/test/staging/sm/strict/unbrand-this.js
@@ -18,32 +18,15 @@ function strict() {
   function bar() {}
 }
 
-var exception;
-
 // Try 'undefined' as a |this| value.
-exception = null;
-try {
+assert.throws(TypeError, function() {
   strict.call(undefined);
-} catch (x) {
-  exception = x;
-}
-assert.sameValue(exception instanceof TypeError, true);
+});
 
 // Try 'null' as a |this| value.
-exception = null;
-try {
+assert.throws(TypeError, function() {
   strict.call(null);
-} catch (x) {
-  exception = x;
-}
-assert.sameValue(exception instanceof TypeError, true);
+});
 
 // An object as a |this| value should be fine.
-exception = null;
-try {
-  strict.call({});
-} catch (x) {
-  exception = x;
-}
-assert.sameValue(exception, null);
-
+strict.call({});
diff --git a/test/staging/sm/syntax/class-error.js b/test/staging/sm/syntax/class-error.js
index c629a19c5a..4f8dda4666 100644
--- a/test/staging/sm/syntax/class-error.js
+++ b/test/staging/sm/syntax/class-error.js
@@ -8,19 +8,7 @@ description: |
   pending
 esid: pending
 ---*/
-function assertThrowsSyntaxError(x) {
-    let success = false;
-    try {
-        eval(x);
-        success = true;
-    } catch (e) {
-        assert.sameValue(e instanceof SyntaxError, true);
-    }
-    assert.sameValue(success, false);
-}
 
-
-assertThrowsSyntaxError("class X { x: 1 }")
-
-if ('assert.sameValue' in this) {
-}
+assert.throws(SyntaxError, function() {
+  eval("class X { x: 1 }");
+});
diff --git a/test/staging/sm/syntax/linefeed-at-eof-in-unterminated-string-or-template.js b/test/staging/sm/syntax/linefeed-at-eof-in-unterminated-string-or-template.js
index ba8351ba86..f6eb38bd9b 100644
--- a/test/staging/sm/syntax/linefeed-at-eof-in-unterminated-string-or-template.js
+++ b/test/staging/sm/syntax/linefeed-at-eof-in-unterminated-string-or-template.js
@@ -13,16 +13,9 @@ esid: pending
 
 function expectSyntaxError(code)
 {
-  try
-  {
+  assert.throws(SyntaxError, function() {
     eval(code);
-    throw new Error("didn't throw");
-  }
-  catch (e)
-  {
-    assert.sameValue(e instanceof SyntaxError, true,
-             "got " + e.name + ", expected SyntaxError");
-  }
+  });
 }
 
 // The fundamental requirements of this test:
diff --git a/test/staging/sm/types/8.12.5-01.js b/test/staging/sm/types/8.12.5-01.js
index e8a7acd117..1c063d1f98 100644
--- a/test/staging/sm/types/8.12.5-01.js
+++ b/test/staging/sm/types/8.12.5-01.js
@@ -7,17 +7,9 @@
 flags:
   - noStrict
 description: |
-  pending
+  Assignments to a property that has a getter but not a setter should not throw a TypeError per ES5 (at least not until strict mode is supported)
 esid: pending
 ---*/
-//-----------------------------------------------------------------------------
-var BUGNUMBER = 523846;
-var summary =
-  "Assignments to a property that has a getter but not a setter should not " +
-  "throw a TypeError per ES5 (at least not until strict mode is supported)";
-var actual = "Early failure";
-var expect = "No errors";
-
 
 var o = { get p() { return "a"; } };
 
@@ -55,56 +47,7 @@ function strictTest2()
   assert.sameValue(y.p, "a");
 }
 
-var errors = [];
-try
-{
-  try
-  {
-    test1();
-  }
-  catch (e)
-  {
-    errors.push(e);
-  }
-
-  try
-  {
-    test2();
-  }
-  catch (e)
-  {
-    errors.push(e);
-  }
-
-  try
-  {
-    strictTest1();
-    errors.push("strictTest1 didn't fail");
-  }
-  catch (e)
-  {
-    if (!(e instanceof TypeError))
-      errors.push("strictTest1 didn't fail with a TypeError: " + e);
-  }
-
-  try
-  {
-    strictTest2();
-    errors.push("strictTest2 didn't fail");
-  }
-  catch (e)
-  {
-    if (!(e instanceof TypeError))
-      errors.push("strictTest2 didn't fail with a TypeError: " + e);
-  }
-}
-catch (e)
-{
-  errors.push("Unexpected error: " + e);
-}
-finally
-{
-  actual = errors.length > 0 ? errors.join(", ") : "No errors";
-}
-
-assert.sameValue(expect, actual, summary);
+test1();
+test2();
+assert.throws(TypeError, strictTest1);
+assert.throws(TypeError, strictTest2);