Transform legacy format to harness assertions: test/built-ins/P*/**/*.js

test/built-ins/Promise/all/S25.4.4.1_A1.1_T1.js

@@ -7,7 +7,4 @@ es6id: 25.4.4.1_A1.1_T1
 author: Sam Mikes
 description: Promise.all is callable
 ---*/
-
-if ((typeof Promise.all) !== "function") {
-  throw new Test262Error('Expected Promise.all to be a function');
-}
+assert.sameValue(typeof Promise.all, "function", 'The value of `typeof Promise.all` is expected to be "function"');

test/built-ins/Promise/all/S25.4.4.1_A2.1_T1.js

@@ -9,6 +9,4 @@ description: Promise.all returns a Promise
 ---*/
 
 var p = Promise.all([]);
-if (!(p instanceof Promise)) {
-  throw new Test262Error('Expected p to be a Promise');
-}
+assert(!!(p instanceof Promise), 'The value of !!(p instanceof Promise) is expected to be true');

test/built-ins/Promise/all/S25.4.4.1_A2.3_T1.js

@@ -12,7 +12,5 @@ flags: [async]
 var arg = [];
 
 Promise.all(arg).then(function(result) {
-  if (!(result instanceof Array)) {
-    throw new Test262Error("expected an array from Promise.all, got " + result);
-  }
+  assert(!!(result instanceof Array), 'The value of !!(result instanceof Array) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A2.3_T2.js

@@ -12,7 +12,5 @@ flags: [async]
 var arg = [];
 
 Promise.all(arg).then(function(result) {
-  if (result.length !== 0) {
-    throw new Test262Error("expected an empty array from Promise.all([]), got " + result);
-  }
+  assert.sameValue(result.length, 0, 'The value of result.length is expected to be 0');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A2.3_T3.js

@@ -12,7 +12,5 @@ flags: [async]
 var arg = [];
 
 Promise.all(arg).then(function(result) {
-  if (result === arg) {
-    throw new Test262Error("expected a new array from Promise.all but argument was re-used");
-  }
+  assert.notSameValue(result, arg, 'The value of result is expected to not equal the value of `arg`');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A3.1_T1.js

@@ -17,7 +17,5 @@ var nonIterable = 3;
 Promise.all(nonIterable).then(function() {
   throw new Test262Error('Promise unexpectedly resolved: Promise.all(nonIterable) should throw TypeError');
 }, function(err) {
-  if (!(err instanceof TypeError)) {
-    throw new Test262Error('Expected TypeError, got ' + err);
-  }
+  assert(!!(err instanceof TypeError), 'The value of !!(err instanceof TypeError) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A3.1_T2.js

@@ -16,7 +16,5 @@ flags: [async]
 Promise.all(new Error("abrupt")).then(function() {
   throw new Test262Error('Promise unexpectedly resolved: Promise.all(abruptCompletion) should throw TypeError');
 }, function(err) {
-  if (!(err instanceof TypeError)) {
-    throw new Test262Error('Expected TypeError, got ' + err);
-  }
+  assert(!!(err instanceof TypeError), 'The value of !!(err instanceof TypeError) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A3.1_T3.js

@@ -22,7 +22,5 @@ Object.defineProperty(iterThrows, Symbol.iterator, {
 Promise.all(iterThrows).then(function() {
   throw new Test262Error('Promise unexpectedly fulfilled: Promise.all(iterThrows) should throw TypeError');
 }, function(err) {
-  if (!(err instanceof Error)) {
-    throw new Test262Error('Expected promise to be rejected with error, got ' + err);
-  }
+  assert(!!(err instanceof Error), 'The value of !!(err instanceof Error) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A5.1_T1.js

@@ -25,5 +25,5 @@ iterThrows[Symbol.iterator] = function() {
 Promise.all(iterThrows).then(function() {
   throw new Test262Error('Promise unexpectedly resolved: Promise.all(iterThrows) should throw TypeError');
 }, function(reason) {
-  assert.sameValue(reason, error);
+  assert.sameValue(reason, error, 'The value of reason is expected to equal the value of error');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A7.1_T1.js

@@ -16,16 +16,8 @@ var p1 = Promise.resolve(3);
 var pAll = Promise.all([p1]);
 
 pAll.then(function(result) {
-  if (!(pAll instanceof Promise)) {
-    throw new Test262Error("Expected Promise.all() to be promise, actually " + pAll);
-  }
-  if (!(result instanceof Array)) {
-    throw new Test262Error("Expected Promise.all() to be promise for an Array, actually " + result);
-  }
-  if (result.length !== 1) {
-    throw new Test262Error("Expected Promise.all([p1]) to be a promise for one-element Array, actually " + result);
-  }
-  if (result[0] !== 3) {
-    throw new Test262Error("Expected result[0] to be 3, actually " + result[0]);
-  }
+  assert(!!(pAll instanceof Promise), 'The value of !!(pAll instanceof Promise) is expected to be true');
+  assert(!!(result instanceof Array), 'The value of !!(result instanceof Array) is expected to be true');
+  assert.sameValue(result.length, 1, 'The value of result.length is expected to be 1');
+  assert.sameValue(result[0], 3, 'The value of result[0] is expected to be 3');
 }).then($DONE, $DONE);

test/built-ins/Promise/all/S25.4.4.1_A8.2_T1.js

@@ -19,9 +19,7 @@ var rejectP1,
 Promise.all([p1, p2]).then(function(resolve) {
   throw new Test262Error("Did not expect promise to be fulfilled.");
 }, function(rejected) {
-  if (rejected !== 1) {
-    throw new Test262Error("Expected promise to be rejected with 1, actually " + rejected);
-  }
+  assert.sameValue(rejected, 1, 'The value of rejected is expected to be 1');
 }).then($DONE, $DONE);
 
 rejectP1(1);

test/built-ins/Promise/all/S25.4.4.1_A8.2_T2.js

@@ -19,9 +19,7 @@ var rejectP2,
 Promise.all([p1, p2]).then(function() {
   throw new Test262Error("Did not expect promise to be fulfilled.");
 }, function(rejected) {
-  if (rejected !== 2) {
-    throw new Test262Error("Expected promise to be rejected with 2, actually " + rejected);
-  }
+  assert.sameValue(rejected, 2, 'The value of rejected is expected to be 2');
 }).then($DONE, $DONE);
 
 rejectP2(2);

test/built-ins/Promise/prototype/S25.4.4.2_A1.1_T1.js

@@ -9,7 +9,8 @@ es6id: S25.4.4.2_A1.1_T1
 author: Sam Mikes
 description: Promise prototype exists
 ---*/
-
-if (Promise.prototype === undefined) {
-  throw new Test262Error("Expected Promise.prototype to be defined.");
-}
+assert.notSameValue(
+  Promise.prototype,
+  undefined,
+  'The value of Promise.prototype is expected to not equal ``undefined``'
+);

test/built-ins/Promise/prototype/S25.4.5_A3.1_T1.js

@@ -8,7 +8,8 @@ es6id: S25.4.5_A3.1_T1
 author: Sam Mikes
 description: Promise.prototype.constructor is the Promise constructor
 ---*/
-
-if (Promise.prototype.constructor !== Promise) {
-  throw new Test262Error("Expected Promise.prototype.constructor to be Promise");
-}
+assert.sameValue(
+  Promise.prototype.constructor,
+  Promise,
+  'The value of Promise.prototype.constructor is expected to equal the value of Promise'
+);

test/built-ins/Promise/prototype/catch/S25.4.5.1_A1.1_T1.js

@@ -8,7 +8,7 @@ es6id: S25.4.5.1_A1.1_T1
 author: Sam Mikes
 description: Promise.prototype.catch is a function
 ---*/
-
-if (!(Promise.prototype.catch instanceof Function)) {
-  throw new Test262Error("Expected Promise.prototype.catch to be a function");
-}
+assert(
+  !!(Promise.prototype.catch instanceof Function),
+  'The value of !!(Promise.prototype.catch instanceof Function) is expected to be true'
+);

test/built-ins/Promise/prototype/catch/S25.4.5.1_A2.1_T1.js

@@ -11,6 +11,7 @@ description: catch is a method on a Promise
 
 var p = Promise.resolve(3);
 
-if (!(p.catch instanceof Function)) {
-  throw new Test262Error("Expected p.catch to be a function");
-}
+assert(
+  !!(p.catch instanceof Function),
+  'The value of !!(p.catch instanceof Function) is expected to be true'
+);

test/built-ins/Promise/prototype/catch/S25.4.5.1_A3.1_T1.js

@@ -10,14 +10,12 @@ description: catch is implemented in terms of then
 flags: [async]
 ---*/
 
-var obj = {};
+var arg = {};
 
-var p = Promise.resolve(obj);
+var p = Promise.resolve(arg);
 
 p.catch(function() {
   throw new Test262Error("Should not be called - promise is fulfilled");
-}).then(function(arg) {
-  if (arg !== obj) {
-    throw new Test262Error("Expected promise to be fulfilled with obj, got " + arg);
-  }
+}).then(function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
 }).then($DONE, $DONE);

test/built-ins/Promise/prototype/catch/S25.4.5.1_A3.1_T2.js

@@ -10,14 +10,12 @@ description: catch is implemented in terms of then
 flags: [async]
 ---*/
 
-var obj = {};
+var arg = {};
 
-var p = Promise.reject(obj);
+var p = Promise.reject(arg);
 
 p.then(function() {
   throw new Test262Error("Should not be called: did not expect promise to be fulfilled");
-}).catch(function(arg) {
-  if (arg !== obj) {
-    throw new Test262Error("Should have been rejected with reason obj, got " + arg);
-  }
+}).catch(function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
 }).then($DONE, $DONE);

test/built-ins/Promise/prototype/then/S25.4.5.3_A1.1_T1.js

@@ -8,7 +8,7 @@ es6id: S25.4.5.3_A1.1_T1
 author: Sam Mikes
 description: Promise.prototype.then is a function of two arguments
 ---*/
-
-if (!(Promise.prototype.then instanceof Function)) {
-  throw new Test262Error("Expected Promise.prototype.then to be a function");
-}
+assert(
+  !!(Promise.prototype.then instanceof Function),
+  'The value of !!(Promise.prototype.then instanceof Function) is expected to be true'
+);

test/built-ins/Promise/prototype/then/S25.4.5.3_A1.1_T2.js

@@ -11,10 +11,5 @@ description: Promise.prototype.then is a function of two arguments
 
 var p = new Promise(function() {});
 
-if (!(p.then instanceof Function)) {
-  throw new Test262Error("Expected p.then to be a function");
-}
-
-if (p.then.length !== 2) {
-  throw new Test262Error("Expected p.then to be a function of two arguments");
-}
+assert(!!(p.then instanceof Function), 'The value of !!(p.then instanceof Function) is expected to be true');
+assert.sameValue(p.then.length, 2, 'The value of p.then.length is expected to be 2');

test/built-ins/Promise/prototype/then/S25.4.5.3_A4.1_T1.js

@@ -11,12 +11,10 @@ description: Promise.prototype.then accepts 'undefined' as arg1, arg2
 flags: [async]
 ---*/
 
-var obj = {};
-var p = Promise.resolve(obj);
+var arg = {};
+var p = Promise.resolve(arg);
 
 p.then(undefined, undefined)
-  .then(function(arg) {
-    if (arg !== obj) {
-      throw new Test262Error("Expected resolution object to be passed through, got " + arg);
-    }
-  }).then($DONE, $DONE);
+  .then(function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
+}).then($DONE, $DONE);

test/built-ins/Promise/prototype/then/S25.4.5.3_A4.1_T2.js

@@ -11,13 +11,11 @@ description: Promise.prototype.then accepts 'undefined' as arg1, arg2
 flags: [async]
 ---*/
 
-var obj = {};
-var p = Promise.reject(obj);
+var arg = {};
+var p = Promise.reject(arg);
 
 p.then(undefined, undefined).then(function() {
   throw new Test262Error("Should not be called -- promise was rejected.");
-}, function(arg) {
-  if (arg !== obj) {
-    throw new Test262Error("Expected resolution object to be passed through, got " + arg);
-  }
+}, function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
 }).then($DONE, $DONE);

test/built-ins/Promise/prototype/then/S25.4.5.3_A4.2_T1.js

@@ -11,12 +11,10 @@ description: Promise.prototype.then treats non-callable arg1, arg2 as undefined
 flags: [async]
 ---*/
 
-var obj = {};
-var p = Promise.resolve(obj);
+var arg = {};
+var p = Promise.resolve(arg);
 
 p.then(3, 5)
-  .then(function(arg) {
-    if (arg !== obj) {
-      throw new Test262Error("Expected resolution object to be passed through, got " + arg);
-    }
-  }).then($DONE, $DONE);
+  .then(function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
+}).then($DONE, $DONE);

test/built-ins/Promise/prototype/then/S25.4.5.3_A4.2_T2.js

@@ -11,13 +11,11 @@ description: Promise.prototype.then treats non-callable arg1, arg2 as undefined
 flags: [async]
 ---*/
 
-var obj = {};
-var p = Promise.reject(obj);
+var arg = {};
+var p = Promise.reject(arg);
 
 p.then(3, 5).then(function() {
   throw new Test262Error("Should not be called -- promise was rejected.");
-}, function(arg) {
-  if (arg !== obj) {
-    throw new Test262Error("Expected resolution object to be passed through, got " + arg);
-  }
+}, function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
 }).then($DONE, $DONE);

test/built-ins/Promise/prototype/then/S25.4.5.3_A5.3_T1.js

@@ -26,7 +26,7 @@ p.then(function() {
   throw new Test262Error("Should not be called -- Promise rejected.");
 }, function() {
   sequence.push(3);
-  assert.sameValue(sequence.length, 3);
+  assert.sameValue(sequence.length, 3, 'The value of sequence.length is expected to be 3');
   checkSequence(sequence, "Should be first");
 }).catch($DONE);
 
@@ -36,12 +36,12 @@ Promise.resolve().then(function() {
     throw new Test262Error("Should not be called (2) -- Promise rejected.");
   }, function() {
     sequence.push(5);
-    assert.sameValue(sequence.length, 5);
+    assert.sameValue(sequence.length, 5, 'The value of sequence.length is expected to be 5');
   checkSequence(sequence, "Should be third");
   }).then($DONE, $DONE);
 
   sequence.push(4);
-  assert.sameValue(sequence.length, 4);
+  assert.sameValue(sequence.length, 4, 'The value of sequence.length is expected to be 4');
   checkSequence(sequence, "Should be second");
 }).catch($DONE);
 

test/built-ins/Promise/race/S25.4.4.3_A1.1_T1.js

@@ -7,7 +7,4 @@ es6id: S25.4.4.3_A1.1_T1
 author: Sam Mikes
 description: Promise.race is callable
 ---*/
-
-if (typeof Promise.race !== "function") {
-  throw new Test262Error("Expected Promise.race to be a function, actually " + typeof Promise.race);
-}
+assert.sameValue(typeof Promise.race, "function", 'The value of `typeof Promise.race` is expected to be "function"');

test/built-ins/Promise/race/S25.4.4.3_A2.1_T1.js

@@ -10,6 +10,4 @@ description: Promise.race returns a new promise
 
 var p = Promise.race([]);
 
-if (!(p instanceof Promise)) {
-  throw new Test262Error("Expected Promise.race([]) to return a promise.");
-}
+assert(!!(p instanceof Promise), 'The value of !!(p instanceof Promise) is expected to be true');

test/built-ins/Promise/race/S25.4.4.3_A2.2_T1.js

@@ -14,7 +14,5 @@ var nonIterable = 3;
 Promise.race(nonIterable).then(function() {
   throw new Test262Error('Promise unexpectedly fulfilled: Promise.race(nonIterable) should throw TypeError');
 }, function(err) {
-  if (!(err instanceof TypeError)) {
-    throw new Test262Error('Expected TypeError, got ' + err);
-  }
+  assert(!!(err instanceof TypeError), 'The value of !!(err instanceof TypeError) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/race/S25.4.4.3_A2.2_T2.js

@@ -12,7 +12,5 @@ flags: [async]
 Promise.race(new Error("abrupt")).then(function() {
   throw new Test262Error('Promise unexpectedly resolved: Promise.race(abruptCompletion) should throw TypeError');
 }, function(err) {
-  if (!(err instanceof TypeError)) {
-    throw new Test262Error('Expected TypeError, got ' + err);
-  }
+  assert(!!(err instanceof TypeError), 'The value of !!(err instanceof TypeError) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/race/S25.4.4.3_A2.2_T3.js

@@ -23,7 +23,5 @@ Object.defineProperty(iterThrows, Symbol.iterator, {
 Promise.race(iterThrows).then(function() {
   throw new Test262Error('Promise unexpectedly fulfilled: Promise.race(iterThrows) should throw');
 }, function(err) {
-  if (!(err instanceof Error)) {
-    throw new Test262Error('Expected Promise to be rejected with an error, got ' + err);
-  }
+  assert(!!(err instanceof Error), 'The value of !!(err instanceof Error) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/race/S25.4.4.3_A4.1_T1.js

@@ -22,5 +22,5 @@ iterThrows[Symbol.iterator] = function() {
 Promise.race(iterThrows).then(function() {
   throw new Test262Error('Promise unexpectedly fulfilled: Promise.race(iterThrows) should throw TypeError');
 }, function(reason) {
-  assert.sameValue(reason, error);
+  assert.sameValue(reason, error, 'The value of reason is expected to equal the value of error');
 }).then($DONE, $DONE);

test/built-ins/Promise/race/S25.4.4.3_A4.1_T2.js

@@ -29,7 +29,5 @@ Object.defineProperty(iterThrows, Symbol.iterator, {
 Promise.race(iterThrows).then(function() {
   throw new Test262Error('Promise unexpectedly fulfilled: Promise.race(iterThrows) should throw TypeError');
 }, function(err) {
-  if (!(err instanceof TypeError)) {
-    throw new Test262Error('Expected TypeError, got ' + err);
-  }
+  assert(!!(err instanceof TypeError), 'The value of !!(err instanceof TypeError) is expected to be true');
 }).then($DONE, $DONE);

test/built-ins/Promise/race/S25.4.4.3_A6.2_T1.js

@@ -20,17 +20,17 @@ p.then(function() {
   throw new Test262Error("Should not fulfill.");
 }, function() {
   sequence.push(4);
-  assert.sameValue(sequence.length, 4);
+  assert.sameValue(sequence.length, 4, 'The value of sequence.length is expected to be 4');
 checkSequence(sequence, "This happens second");
 }).catch($DONE);
 
 Promise.resolve().then(function() {
   sequence.push(3);
-  assert.sameValue(sequence.length, 3);
+  assert.sameValue(sequence.length, 3, 'The value of sequence.length is expected to be 3');
   checkSequence(sequence, "This happens first");
 }).then(function() {
   sequence.push(5);
-  assert.sameValue(sequence.length, 5);
+  assert.sameValue(sequence.length, 5, 'The value of sequence.length is expected to be 5');
   checkSequence(sequence, "This happens third");
 }).then($DONE, $DONE);
 

test/built-ins/Promise/race/S25.4.4.3_A7.1_T1.js

@@ -17,23 +17,21 @@ var p1 = Promise.resolve(1),
 
 sequence.push(1);
 
-p.then(function(arg) {
-  if (arg !== 1) {
-    throw new Test262Error("Expected promise to be fulfilled with 1, got " + arg);
-  }
+p.then(function(result) {
+  assert.sameValue(result, 1, 'The value of result is expected to be 1');
 
   sequence.push(4);
-  assert.sameValue(sequence.length, 4);
+  assert.sameValue(sequence.length, 4, 'The value of sequence.length is expected to be 4');
   checkSequence(sequence, "This happens second");
 }).catch($DONE);
 
 Promise.resolve().then(function() {
   sequence.push(3);
-  assert.sameValue(sequence.length, 3);
+  assert.sameValue(sequence.length, 3, 'The value of sequence.length is expected to be 3');
   checkSequence(sequence, "This happens first");
 }).then(function() {
   sequence.push(5);
-  assert.sameValue(sequence.length, 5);
+  assert.sameValue(sequence.length, 5, 'The value of sequence.length is expected to be 5');
   checkSequence(sequence, "This happens third");
 }).then($DONE, $DONE);
 

test/built-ins/Promise/race/S25.4.4.3_A7.1_T2.js

@@ -17,23 +17,21 @@ var p1 = Promise.resolve(1),
 
 sequence.push(1);
 
-p.then(function(arg) {
-  if (arg !== 1) {
-    throw new Test262Error("Expected promise to be fulfilled with 1, got " + arg);
-  }
+p.then(function(result) {
+  assert.sameValue(result, 1, 'The value of result is expected to be 1');
 
   sequence.push(4);
-  assert.sameValue(sequence.length, 4);
+  assert.sameValue(sequence.length, 4, 'The value of sequence.length is expected to be 4');
   checkSequence(sequence, "This happens second");
 }).catch($DONE);
 
 Promise.resolve().then(function() {
   sequence.push(3);
-  assert.sameValue(sequence.length, 3);
+  assert.sameValue(sequence.length, 3, 'The value of sequence.length is expected to be 3');
   checkSequence(sequence, "This happens first");
 }).then(function() {
   sequence.push(5);
-  assert.sameValue(sequence.length, 5);
+  assert.sameValue(sequence.length, 5, 'The value of sequence.length is expected to be 5');
   checkSequence(sequence, "This happens third");
 }).then($DONE, $DONE);
 

test/built-ins/Promise/race/S25.4.4.3_A7.1_T3.js

@@ -17,23 +17,21 @@ var p1 = new Promise(function() {}),
 
 sequence.push(1);
 
-p.then(function(arg) {
-  if (arg !== 2) {
-    throw new Test262Error("Expected promise to be fulfilled with 2, got " + arg);
-  }
+p.then(function(result) {
+  assert.sameValue(result, 2, 'The value of result is expected to be 2');
 
   sequence.push(4);
-  assert.sameValue(sequence.length, 4);
+  assert.sameValue(sequence.length, 4, 'The value of sequence.length is expected to be 4');
   checkSequence(sequence, "This happens second");
 }).catch($DONE);
 
 Promise.resolve().then(function() {
   sequence.push(3);
-  assert.sameValue(sequence.length, 3);
+  assert.sameValue(sequence.length, 3, 'The value of sequence.length is expected to be 3');
   checkSequence(sequence, "This happens first");
 }).then(function() {
   sequence.push(5);
-  assert.sameValue(sequence.length, 5);
+  assert.sameValue(sequence.length, 5, 'The value of sequence.length is expected to be 5');
   checkSequence(sequence, "This happens third");
 }).then($DONE, $DONE);
 

test/built-ins/Promise/race/S25.4.4.3_A7.2_T1.js

@@ -19,23 +19,21 @@ sequence.push(1);
 
 p.then(function() {
   throw new Test262Error("Should not be fulfilled - expected rejection.");
-}, function(arg) {
-  if (arg !== 1) {
-    throw new Test262Error("Expected rejection reason to be 1, got " + arg);
-  }
+}, function(result) {
+  assert.sameValue(result, 1, 'The value of result is expected to be 1');
 
   sequence.push(4);
-  assert.sameValue(sequence.length, 4);
+  assert.sameValue(sequence.length, 4, 'The value of sequence.length is expected to be 4');
   checkSequence(sequence, "This happens second");
 }).catch($DONE);
 
 Promise.resolve().then(function() {
   sequence.push(3);
-  assert.sameValue(sequence.length, 3);
+  assert.sameValue(sequence.length, 3, 'The value of sequence.length is expected to be 3');
   checkSequence(sequence, "This happens first");
 }).then(function() {
   sequence.push(5);
-  assert.sameValue(sequence.length, 5);
+  assert.sameValue(sequence.length, 5, 'The value of sequence.length is expected to be 5');
   checkSequence(sequence, "This happens third");
 }).then($DONE, $DONE);
 

test/built-ins/Promise/race/S25.4.4.3_A7.3_T1.js

@@ -19,8 +19,6 @@ var resolveP1, rejectP2,
 rejectP2(new Error("Promise.race should not see this if P1 already resolved"));
 resolveP1(1);
 
-Promise.race([p1, p2]).then(function(arg) {
-  if (arg !== 1) {
-    throw new Test262Error("Expected fulfillment with 1, got " + arg);
-  }
+Promise.race([p1, p2]).then(function(result) {
+  assert.sameValue(result, 1, 'The value of result is expected to be 1');
 }).then($DONE, $DONE);

test/built-ins/Promise/race/S25.4.4.3_A7.3_T2.js

@@ -18,10 +18,8 @@ var resolveP1, rejectP2,
 
 Promise.race([p1, p2]).then(function() {
   throw new Test262Error("Should not be fulfilled: expected rejection.");
-}, function(arg) {
-  if (arg !== 2) {
-    throw new Test262Error("Expected rejection reason to be 2, got " + arg);
-  }
+}, function(result) {
+  assert.sameValue(result, 2, 'The value of result is expected to be 2');
 }).then($DONE, $DONE);
 
 rejectP2(2);

test/built-ins/Promise/reject/S25.4.4.4_A1.1_T1.js

@@ -8,7 +8,8 @@ es6id: S25.4.4.4_A1.1_T1
 author: Sam Mikes
 description: Promise.reject is a function
 ---*/
-
-if ((typeof Promise.reject) !== "function") {
-  throw new Test262Error("Expected Promise.reject to be a function");
-}
+assert.sameValue(
+  typeof Promise.reject,
+  "function",
+  'The value of `typeof Promise.reject` is expected to be "function"'
+);

test/built-ins/Promise/reject/S25.4.4.4_A2.1_T1.js

@@ -18,14 +18,10 @@ flags: [async]
 
 var p = Promise.reject(3);
 
-if (!(p instanceof Promise)) {
-  throw new Test262Error("Expected Promise.reject to return a promise.");
-}
+assert(!!(p instanceof Promise), 'The value of !!(p instanceof Promise) is expected to be true');
 
 p.then(function() {
   throw new Test262Error("Promise should not be fulfilled.");
-}, function(arg) {
-  if (arg !== 3) {
-    throw new Test262Error("Expected promise to be rejected with supplied arg, got " + arg);
-  }
+}, function(result) {
+  assert.sameValue(result, 3, 'The value of result is expected to be 3');
 }).then($DONE, $DONE);

test/built-ins/Promise/resolve/S25.4.4.5_A1.1_T1.js

@@ -8,7 +8,8 @@ es6id: S25.4.4.5_A1.1_T1
 author: Sam Mikes
 description: Promise.resolve is a function
 ---*/
-
-if ((typeof Promise.resolve) !== "function") {
-  throw new Test262Error("Expected Promise.resolve to be a function");
-}
+assert.sameValue(
+  typeof Promise.resolve,
+  "function",
+  'The value of `typeof Promise.resolve` is expected to be "function"'
+);

test/built-ins/Promise/resolve/S25.4.4.5_A2.1_T1.js

@@ -10,6 +10,4 @@ description: Promise.resolve passes through a promise w/ same Constructor
 var p1 = Promise.resolve(1),
   p2 = Promise.resolve(p1);
 
-if (p1 !== p2) {
-  throw new Test262Error("Expected p1 === Promise.resolve(p1) because they have same constructor");
-}
+assert.sameValue(p1, p2, 'The value of p1 is expected to equal the value of p2');

test/built-ins/Promise/resolve/S25.4.4.5_A2.2_T1.js

@@ -13,16 +13,12 @@ var resolveP1,
     resolveP1 = resolve;
   }),
   p2 = Promise.resolve(p1),
-  obj = {};
+  arg = {};
 
-if (p1 !== p2) {
-  throw new Test262Error("Expected p1 === Promise.resolve(p1) because they have same constructor");
-}
+assert.sameValue(p1, p2, 'The value of p1 is expected to equal the value of p2');
 
-p2.then(function(arg) {
-  if (arg !== obj) {
-    throw new Test262Error("Expected promise to be resolved with obj, actually " + arg);
-  }
+p2.then(function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
 }).then($DONE, $DONE);
 
-resolveP1(obj);
+resolveP1(arg);

test/built-ins/Promise/resolve/S25.4.4.5_A2.3_T1.js

@@ -13,18 +13,14 @@ var rejectP1,
     rejectP1 = reject;
   }),
   p2 = Promise.resolve(p1),
-  obj = {};
+  arg = {};
 
-if (p1 !== p2) {
-  throw new Test262Error("Expected p1 === Promise.resolve(p1) because they have same constructor");
-}
+assert.sameValue(p1, p2, 'The value of p1 is expected to equal the value of p2');
 
 p2.then(function() {
   throw new Test262Error("Expected p2 to be rejected, not fulfilled.");
-}, function(arg) {
-  if (arg !== obj) {
-    throw new Test262Error("Expected promise to be rejected with reason obj, actually " + arg);
-  }
+}, function(result) {
+  assert.sameValue(result, arg, 'The value of result is expected to equal the value of arg');
 }).then($DONE, $DONE);
 
-rejectP1(obj);
+rejectP1(arg);

test/built-ins/Promise/resolve/S25.4.4.5_A4.1_T1.js

@@ -20,7 +20,5 @@ resolveP(p);
 p.then(function() {
   throw new Test262Error("Should not fulfill: should reject with TypeError.");
 }, function(err) {
-  if (!(err instanceof TypeError)) {
-    throw new Test262Error("Expected TypeError, got " + err);
-  }
+  assert(!!(err instanceof TypeError), 'The value of !!(err instanceof TypeError) is expected to be true');
 }).then($DONE, $DONE);