assert: check object prototype in deepEqual

Objects with different prototypes should not be considered deep equal,
e.g. `assert.deepEqual({}, [])` should throw. Previously `deepEqual`
was implemented as per CommonJS Unit Testing/1.0 spec. It states that
objects should have 'an identical "prototype" property' to be
considered deep equal, which is incorrect. Instead object prototypes
should be compared, i.e. `Object.getPrototypeOf` or `__proto__`.

Fixes: #620

lib/assert.js

@@ -199,11 +199,12 @@ function isArguments(object) {
 function objEquiv(a, b) {
   if (util.isNullOrUndefined(a) || util.isNullOrUndefined(b))
     return false;
-  // an identical 'prototype' property.
-  if (a.prototype !== b.prototype) return false;
   // if one is a primitive, the other must be same
   if (util.isPrimitive(a) || util.isPrimitive(b))
     return a === b;
+  // an identical prototype.
+  if (Object.getPrototypeOf(a) !== Object.getPrototypeOf(b))
+    return false;
   var aIsArgs = isArguments(a),
       bIsArgs = isArguments(b);
   if ((aIsArgs && !bIsArgs) || (!aIsArgs && bIsArgs))

test/parallel/test-assert.js

@@ -91,7 +91,7 @@ assert.doesNotThrow(makeBlock(a.deepEqual, {a: 4, b: '2'}, {a: 4, b: '2'}));
 assert.doesNotThrow(makeBlock(a.deepEqual, [4], ['4']));
 assert.throws(makeBlock(a.deepEqual, {a: 4}, {a: 4, b: true}),
               a.AssertionError);
-assert.doesNotThrow(makeBlock(a.deepEqual, ['a'], {0: 'a'}));
+assert.throws(makeBlock(a.deepEqual, ['a'], {0: 'a'}));
 //(although not necessarily the same order),
 assert.doesNotThrow(makeBlock(a.deepEqual, {a: 4, b: '1'}, {b: '1', a: 4}));
 var a1 = [1, 2, 3];
@@ -144,10 +144,16 @@ if (typeof Symbol === 'symbol') {
 }
 
 // primitive wrappers and object
-assert.doesNotThrow(makeBlock(a.deepEqual, new String('a'), ['a']), a.AssertionError);
-assert.doesNotThrow(makeBlock(a.deepEqual, new String('a'), {0: 'a'}), a.AssertionError);
-assert.doesNotThrow(makeBlock(a.deepEqual, new Number(1), {}), a.AssertionError);
-assert.doesNotThrow(makeBlock(a.deepEqual, new Boolean(true), {}), a.AssertionError);
+assert.throws(makeBlock(a.deepEqual, new String('a'), ['a']),
+              a.AssertionError);
+assert.throws(makeBlock(a.deepEqual, new String('a'),{0: 'a'}),
+              a.AssertionError);
+assert.throws(makeBlock(a.deepEqual, new Number(1), {}), a.AssertionError);
+assert.throws(makeBlock(a.deepEqual, new Boolean(true), {}), a.AssertionError);
+
+// prototypes
+assert.throws(makeBlock(assert.deepEqual, Object.create({}), {}),
+              a.AssertionError);
 
 // Testing the throwing
 function thrower(errorConstructor) {

test/parallel/test-url.js

@@ -867,8 +867,8 @@ for (var u in parseTests) {
     }
   });
 
-  assert.deepEqual(actual, expected);
-  assert.deepEqual(spaced, expected);
+  assert.deepEqual(JSON.parse(JSON.stringify(actual)), expected);
+  assert.deepEqual(JSON.parse(JSON.stringify(spaced)), expected);
 
   var expected = parseTests[u].href,
       actual = url.format(parseTests[u]);
@@ -937,7 +937,7 @@ for (var u in parseTestsWithQueryString) {
     }
   }
 
-  assert.deepEqual(actual, expected);
+  assert.deepEqual(JSON.parse(JSON.stringify(actual)), expected);
 }
 
 // some extra formatting tests, just to verify

test/parallel/test-vm-create-context-accessors.js

@@ -23,4 +23,5 @@ Object.defineProperty(ctx, 'setter', {
 ctx = vm.createContext(ctx);
 
 var result = vm.runInContext('setter = "test";[getter,setter]', ctx);
-assert.deepEqual(result, ['ok', 'ok=test']);
+assert.equal(result[0], 'ok');
+assert.equal(result[1], 'ok=test');