diff --git a/harness/sm/non262-generators-shell.js b/harness/sm/non262-generators-shell.js
index 46161a803c..ece16e815b 100644
--- a/harness/sm/non262-generators-shell.js
+++ b/harness/sm/non262-generators-shell.js
@@ -10,7 +10,7 @@ function assertFalse(a) { assertEq(a, false) }
 function assertTrue(a) { assertEq(a, true) }
 function assertNotEq(found, not_expected) { assertEq(Object.is(found, not_expected), false) }
 function assertIteratorResult(result, value, done) {
-    assertDeepEq(result.value, value);
+    assert.deepEqual(result.value, value);
     assertEq(result.done, done);
 }
 function assertIteratorNext(iter, value) {
diff --git a/harness/sm/non262-shell.js b/harness/sm/non262-shell.js
index f124b34057..11fa3f23d2 100644
--- a/harness/sm/non262-shell.js
+++ b/harness/sm/non262-shell.js
@@ -188,190 +188,4 @@ allow_unused: True
     }
   }
 
-  globalThis.assertDeepEq = (function(){
-    var call = Function.prototype.call,
-      Array_isArray = Array.isArray,
-      Array_includes = call.bind(Array.prototype.includes),
-      Map_ = Map,
-      Error_ = Error,
-      Symbol_ = Symbol,
-      Symbol_keyFor = Symbol.keyFor,
-      Symbol_description = call.bind(Object.getOwnPropertyDescriptor(Symbol.prototype, "description").get),
-      Map_has = call.bind(Map.prototype.has),
-      Map_get = call.bind(Map.prototype.get),
-      Map_set = call.bind(Map.prototype.set),
-      Object_toString = call.bind(Object.prototype.toString),
-      Function_toString = call.bind(Function.prototype.toString),
-      Object_getPrototypeOf = Object.getPrototypeOf,
-      Object_hasOwnProperty = call.bind(Object.prototype.hasOwnProperty),
-      Object_getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor,
-      Object_isExtensible = Object.isExtensible,
-      Object_getOwnPropertyNames = Object.getOwnPropertyNames;
-
-    // Return true iff ES6 Type(v) isn't Object.
-    // Note that `typeof document.all === "undefined"`.
-    function isPrimitive(v) {
-      return (v === null ||
-          v === undefined ||
-          typeof v === "boolean" ||
-          typeof v === "number" ||
-          typeof v === "string" ||
-          typeof v === "symbol");
-    }
-
-    function assertSameValue(a, b, msg) {
-      try {
-        assertEq(a, b);
-      } catch (exc) {
-        throw Error_(exc.message + (msg ? " " + msg : ""));
-      }
-    }
-
-    function assertSameClass(a, b, msg) {
-      var ac = Object_toString(a), bc = Object_toString(b);
-      assertSameValue(ac, bc, msg);
-      switch (ac) {
-      case "[object Function]":
-        if (typeof isProxy !== "undefined" && !isProxy(a) && !isProxy(b))
-          assertSameValue(Function_toString(a), Function_toString(b), msg);
-      }
-    }
-
-    function at(prevmsg, segment) {
-      return prevmsg ? prevmsg + segment : "at _" + segment;
-    }
-
-    // Assert that the arguments a and b are thoroughly structurally equivalent.
-    //
-    // For the sake of speed, we cut a corner:
-    //    var x = {}, y = {}, ax = [x];
-    //    assertDeepEq([ax, x], [ax, y]);  // passes (?!)
-    //
-    // Technically this should fail, since the two object graphs are different.
-    // (The graph of [ax, y] contains one more object than the graph of [ax, x].)
-    //
-    // To get technically correct behavior, pass {strictEquivalence: true}.
-    // This is slower because we have to walk the entire graph, and Object.prototype
-    // is big.
-    //
-    return function assertDeepEq(a, b, options) {
-      var strictEquivalence = options ? options.strictEquivalence : false;
-
-      function assertSameProto(a, b, msg) {
-        check(Object_getPrototypeOf(a), Object_getPrototypeOf(b), at(msg, ".__proto__"));
-      }
-
-      function failPropList(na, nb, msg) {
-        throw Error_("got own properties " + JSON.stringify(na) + ", expected " + JSON.stringify(nb) +
-               (msg ? " " + msg : ""));
-      }
-
-      function assertSameProps(a, b, msg) {
-        var na = Object_getOwnPropertyNames(a),
-          nb = Object_getOwnPropertyNames(b);
-        if (na.length !== nb.length)
-          failPropList(na, nb, msg);
-
-        // Ignore differences in whether Array elements are stored densely.
-        if (Array_isArray(a)) {
-          na.sort();
-          nb.sort();
-        }
-
-        for (var i = 0; i < na.length; i++) {
-          var name = na[i];
-          if (name !== nb[i])
-            failPropList(na, nb, msg);
-          var da = Object_getOwnPropertyDescriptor(a, name),
-            db = Object_getOwnPropertyDescriptor(b, name);
-          var pmsg = at(msg, /^[_$A-Za-z0-9]+$/.test(name)
-                     ? /0|[1-9][0-9]*/.test(name) ? "[" + name + "]" : "." + name
-                     : "[" + JSON.stringify(name) + "]");
-          assertSameValue(da.configurable, db.configurable, at(pmsg, ".[[Configurable]]"));
-          assertSameValue(da.enumerable, db.enumerable, at(pmsg, ".[[Enumerable]]"));
-          if (Object_hasOwnProperty(da, "value")) {
-            if (!Object_hasOwnProperty(db, "value"))
-              throw Error_("got data property, expected accessor property" + pmsg);
-            check(da.value, db.value, pmsg);
-          } else {
-            if (Object_hasOwnProperty(db, "value"))
-              throw Error_("got accessor property, expected data property" + pmsg);
-            check(da.get, db.get, at(pmsg, ".[[Get]]"));
-            check(da.set, db.set, at(pmsg, ".[[Set]]"));
-          }
-        }
-      };
-
-      const wellKnownSymbols = Reflect.ownKeys(Symbol)
-                                      .map(key => Symbol[key])
-                                      .filter(value => typeof value === "symbol");
-
-      // The standard doesn't offer a convenient way to distinguish well-known
-      // symbols from user-created symbols.
-      function isSimilarSymbol(a, b) {
-        // Fast path for same symbols.
-        if (a === b) {
-          return true;
-        }
-
-        // 1. Symbol descriptions must match.
-        // 2. Either both symbols are in the registry or none is.
-        // 3. Neither symbol must be a well-known symbol, because those are
-        //    already handled through the fast path.
-        return Symbol_description(a) === Symbol_description(b) &&
-               Symbol_keyFor(a) === Symbol_keyFor(b) &&
-               !Array_includes(wellKnownSymbols, a) &&
-               !Array_includes(wellKnownSymbols, b);
-      }
-
-      var ab = new Map_();
-      var bpath = new Map_();
-
-      function check(a, b, path) {
-        if (typeof a === "symbol") {
-          // Symbols are primitives, but they have identity.
-          // Symbol("x") !== Symbol("x") but
-          // assertDeepEq(Symbol("x"), Symbol("x")) should pass.
-          if (typeof b !== "symbol") {
-            throw Error_("got " + String(a) + ", expected " + String(b) + " " + path);
-          } else if (!isSimilarSymbol(a, b)) {
-            throw Error_("got " + String(a) + ", expected " + String(b) + " " + path);
-          } else if (Map_has(ab, a)) {
-            assertSameValue(Map_get(ab, a), b, path);
-          } else if (Map_has(bpath, b)) {
-            var bPrevPath = Map_get(bpath, b) || "_";
-            throw Error_("got distinct symbols " + at(path, "") + " and " +
-                   at(bPrevPath, "") + ", expected the same symbol both places");
-          } else {
-            Map_set(ab, a, b);
-            Map_set(bpath, b, path);
-          }
-        } else if (isPrimitive(a)) {
-          assertSameValue(a, b, path);
-        } else if (isPrimitive(b)) {
-          throw Error_("got " + Object_toString(a) + ", expected " + String(b) + " " + path);
-        } else if (Map_has(ab, a)) {
-          assertSameValue(Map_get(ab, a), b, path);
-        } else if (Map_has(bpath, b)) {
-          var bPrevPath = Map_get(bpath, b) || "_";
-          throw Error_("got distinct objects " + at(path, "") + " and " + at(bPrevPath, "") +
-                 ", expected the same object both places");
-        } else {
-          Map_set(ab, a, b);
-          Map_set(bpath, b, path);
-          if (a !== b || strictEquivalence) {
-            assertSameClass(a, b, path);
-            assertSameProto(a, b, path);
-            assertSameProps(a, b, path);
-            assertSameValue(Object_isExtensible(a),
-                    Object_isExtensible(b),
-                    at(path, ".[[Extensible]]"));
-          }
-        }
-      }
-
-      check(a, b, "");
-    };
-  })();
-
 })();
diff --git a/test/staging/sm/generators/delegating-yield-12.js b/test/staging/sm/generators/delegating-yield-12.js
index d7d17e8375..3d3cda963d 100644
--- a/test/staging/sm/generators/delegating-yield-12.js
+++ b/test/staging/sm/generators/delegating-yield-12.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js]
+includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js, deepEqual.js]
 flags:
   - noStrict
 description: |
diff --git a/test/staging/sm/generators/delegating-yield-2.js b/test/staging/sm/generators/delegating-yield-2.js
index 5b68adceae..ebb8b8230e 100644
--- a/test/staging/sm/generators/delegating-yield-2.js
+++ b/test/staging/sm/generators/delegating-yield-2.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js]
+includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js, deepEqual.js]
 flags:
   - noStrict
 description: |
diff --git a/test/staging/sm/generators/delegating-yield-3.js b/test/staging/sm/generators/delegating-yield-3.js
index 3d709df845..b2275d9772 100644
--- a/test/staging/sm/generators/delegating-yield-3.js
+++ b/test/staging/sm/generators/delegating-yield-3.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js]
+includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js, deepEqual.js]
 flags:
   - noStrict
 description: |
diff --git a/test/staging/sm/generators/delegating-yield-4.js b/test/staging/sm/generators/delegating-yield-4.js
index 44b8aba333..0c86af847b 100644
--- a/test/staging/sm/generators/delegating-yield-4.js
+++ b/test/staging/sm/generators/delegating-yield-4.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js]
+includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js, deepEqual.js]
 flags:
   - noStrict
 description: |
diff --git a/test/staging/sm/generators/iteration.js b/test/staging/sm/generators/iteration.js
index f209db59f9..365e179e39 100644
--- a/test/staging/sm/generators/iteration.js
+++ b/test/staging/sm/generators/iteration.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js]
+includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js, deepEqual.js]
 flags:
   - noStrict
 description: |
diff --git a/test/staging/sm/generators/syntax.js b/test/staging/sm/generators/syntax.js
index 043367de37..f49e5ec699 100644
--- a/test/staging/sm/generators/syntax.js
+++ b/test/staging/sm/generators/syntax.js
@@ -2,7 +2,7 @@
 // This code is governed by the BSD license found in the LICENSE file.
 
 /*---
-includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js]
+includes: [sm/non262.js, sm/non262-shell.js, sm/non262-generators-shell.js, deepEqual.js]
 flags:
   - noStrict
 description: |