assert: add partialDeepStrictEqual

Fixes: https://github.com/nodejs/node/issues/50399

Co-Authored-By: Cristian Barlutiu <cristian.barlutiu@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/54630
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Jithil P Ponnan <jithil@outlook.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>

doc/api/assert.md

@@ -2548,6 +2548,96 @@ assert.throws(throwingFirst, /Second$/);
 Due to the confusing error-prone notation, avoid a string as the second
 argument.
 
+## `assert.partialDeepStrictEqual(actual, expected[, message])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1.0 - Early development
+
+* `actual` {any}
+* `expected` {any}
+* `message` {string|Error}
+
+[`assert.partialDeepStrictEqual()`][] Asserts the equivalence between the `actual` and `expected` parameters through a
+deep comparison, ensuring that all properties in the `expected` parameter are
+present in the `actual` parameter with equivalent values, not allowing type coercion.
+The main difference with [`assert.deepStrictEqual()`][] is that [`assert.partialDeepStrictEqual()`][] does not require
+all properties in the `actual` parameter to be present in the `expected` parameter.
+This method should always pass the same test cases as [`assert.deepStrictEqual()`][], behaving as a super set of it.
+
+```mjs
+import assert from 'node:assert';
+
+assert.partialDeepStrictEqual({ a: 1, b: 2 }, { a: 1, b: 2 });
+// OK
+
+assert.partialDeepStrictEqual({ a: { b: { c: 1 } } }, { a: { b: { c: 1 } } });
+// OK
+
+assert.partialDeepStrictEqual({ a: 1, b: 2, c: 3 }, { a: 1, b: 2 });
+// OK
+
+assert.partialDeepStrictEqual(new Set(['value1', 'value2']), new Set(['value1', 'value2']));
+// OK
+
+assert.partialDeepStrictEqual(new Map([['key1', 'value1']]), new Map([['key1', 'value1']]));
+// OK
+
+assert.partialDeepStrictEqual(new Uint8Array([1, 2, 3]), new Uint8Array([1, 2, 3]));
+// OK
+
+assert.partialDeepStrictEqual(/abc/, /abc/);
+// OK
+
+assert.partialDeepStrictEqual([{ a: 5 }, { b: 5 }], [{ a: 5 }]);
+// OK
+
+assert.partialDeepStrictEqual(new Set([{ a: 1 }, { b: 1 }]), new Set([{ a: 1 }]));
+// OK
+
+assert.partialDeepStrictEqual(new Date(0), new Date(0));
+// OK
+
+assert.partialDeepStrictEqual({ a: 1 }, { a: 1, b: 2 });
+// AssertionError
+
+assert.partialDeepStrictEqual({ a: 1, b: '2' }, { a: 1, b: 2 });
+// AssertionError
+
+assert.partialDeepStrictEqual({ a: { b: 2 } }, { a: { b: '2' } });
+// AssertionError
+```
+
+```cjs
+const assert = require('node:assert');
+
+assert.partialDeepStrictEqual({ a: 1, b: 2 }, { a: 1, b: 2 });
+// OK
+
+assert.partialDeepStrictEqual({ a: { b: { c: 1 } } }, { a: { b: { c: 1 } } });
+// OK
+
+assert.partialDeepStrictEqual({ a: 1, b: 2, c: 3 }, { a: 1, b: 2 });
+// OK
+
+assert.partialDeepStrictEqual([{ a: 5 }, { b: 5 }], [{ a: 5 }]);
+// OK
+
+assert.partialDeepStrictEqual(new Set([{ a: 1 }, { b: 1 }]), new Set([{ a: 1 }]));
+// OK
+
+assert.partialDeepStrictEqual({ a: 1 }, { a: 1, b: 2 });
+// AssertionError
+
+assert.partialDeepStrictEqual({ a: 1, b: '2' }, { a: 1, b: 2 });
+// AssertionError
+
+assert.partialDeepStrictEqual({ a: { b: 2 } }, { a: { b: '2' } });
+// AssertionError
+```
+
 [Object wrappers]: https://developer.mozilla.org/en-US/docs/Glossary/Primitive#Primitive_wrapper_objects_in_JavaScript
 [Object.prototype.toString()]: https://tc39.github.io/ecma262/#sec-object.prototype.tostring
 [`!=` operator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Inequality
@@ -2576,6 +2666,7 @@ argument.
 [`assert.notEqual()`]: #assertnotequalactual-expected-message
 [`assert.notStrictEqual()`]: #assertnotstrictequalactual-expected-message
 [`assert.ok()`]: #assertokvalue-message
+[`assert.partialDeepStrictEqual()`]: #assertpartialdeepstrictequalactual-expected-message
 [`assert.strictEqual()`]: #assertstrictequalactual-expected-message
 [`assert.throws()`]: #assertthrowsfn-error-message
 [`getColorDepth()`]: tty.md#writestreamgetcolordepthenv

lib/assert.js

@@ -21,22 +21,35 @@
 'use strict';
 
 const {
+  ArrayFrom,
+  ArrayIsArray,
   ArrayPrototypeIndexOf,
   ArrayPrototypeJoin,
   ArrayPrototypePush,
   ArrayPrototypeSlice,
   Error,
+  FunctionPrototypeCall,
+  MapPrototypeDelete,
+  MapPrototypeGet,
+  MapPrototypeHas,
+  MapPrototypeSet,
   NumberIsNaN,
   ObjectAssign,
   ObjectIs,
   ObjectKeys,
   ObjectPrototypeIsPrototypeOf,
   ReflectApply,
+  ReflectHas,
+  ReflectOwnKeys,
   RegExpPrototypeExec,
+  SafeMap,
+  SafeSet,
+  SafeWeakSet,
   String,
   StringPrototypeIndexOf,
   StringPrototypeSlice,
   StringPrototypeSplit,
+  SymbolIterator,
 } = primordials;
 
 const {
@@ -50,8 +63,18 @@ const {
 } = require('internal/errors');
 const AssertionError = require('internal/assert/assertion_error');
 const { inspect } = require('internal/util/inspect');
-const { isPromise, isRegExp } = require('internal/util/types');
+const { Buffer } = require('buffer');
-const { isError, deprecate } = require('internal/util');
+const {
+  isKeyObject,
+  isPromise,
+  isRegExp,
+  isMap,
+  isSet,
+  isDate,
+  isWeakSet,
+  isWeakMap,
+} = require('internal/util/types');
+const { isError, deprecate, emitExperimentalWarning } = require('internal/util');
 const { innerOk } = require('internal/assert/utils');
 
 const CallTracker = require('internal/assert/calltracker');
@@ -341,6 +364,191 @@ assert.notStrictEqual = function notStrictEqual(actual, expected, message) {
   }
 };
 
+function isSpecial(obj) {
+  return obj == null || typeof obj !== 'object' || isError(obj) || isRegExp(obj) || isDate(obj);
+}
+
+const typesToCallDeepStrictEqualWith = [
+  isKeyObject, isWeakSet, isWeakMap, Buffer.isBuffer,
+];
+
+/**
+ * Compares two objects or values recursively to check if they are equal.
+ * @param {any} actual - The actual value to compare.
+ * @param {any} expected - The expected value to compare.
+ * @param {Set} [comparedObjects=new Set()] - Set to track compared objects for handling circular references.
+ * @returns {boolean} - Returns `true` if the actual value matches the expected value, otherwise `false`.
+ * @example
+ * compareBranch({a: 1, b: 2, c: 3}, {a: 1, b: 2}); // true
+ */
+function compareBranch(
+  actual,
+  expected,
+  comparedObjects,
+) {
+  // Check for Map object equality
+  if (isMap(actual) && isMap(expected)) {
+    if (actual.size !== expected.size) {
+      return false;
+    }
+    const safeIterator = FunctionPrototypeCall(SafeMap.prototype[SymbolIterator], actual);
+
+    comparedObjects ??= new SafeWeakSet();
+
+    for (const { 0: key, 1: val } of safeIterator) {
+      if (!MapPrototypeHas(expected, key)) {
+        return false;
+      }
+      if (!compareBranch(val, MapPrototypeGet(expected, key), comparedObjects)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  for (const type of typesToCallDeepStrictEqualWith) {
+    if (type(actual) || type(expected)) {
+      if (isDeepStrictEqual === undefined) lazyLoadComparison();
+      return isDeepStrictEqual(actual, expected);
+    }
+  }
+
+  // Check for Set object equality
+  // TODO(aduh95): switch to `SetPrototypeIsSubsetOf` when it's available
+  if (isSet(actual) && isSet(expected)) {
+    if (expected.size > actual.size) {
+      return false; // `expected` can't be a subset if it has more elements
+    }
+
+    if (isDeepEqual === undefined) lazyLoadComparison();
+
+    const actualArray = ArrayFrom(actual);
+    const expectedArray = ArrayFrom(expected);
+    const usedIndices = new SafeSet();
+
+    for (let expectedIdx = 0; expectedIdx < expectedArray.length; expectedIdx++) {
+      const expectedItem = expectedArray[expectedIdx];
+      let found = false;
+
+      for (let actualIdx = 0; actualIdx < actualArray.length; actualIdx++) {
+        if (!usedIndices.has(actualIdx) && isDeepStrictEqual(actualArray[actualIdx], expectedItem)) {
+          usedIndices.add(actualIdx);
+          found = true;
+          break;
+        }
+      }
+
+      if (!found) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  // Check if expected array is a subset of actual array
+  if (ArrayIsArray(actual) && ArrayIsArray(expected)) {
+    if (expected.length > actual.length) {
+      return false;
+    }
+
+    if (isDeepEqual === undefined) lazyLoadComparison();
+
+    // Create a map to count occurrences of each element in the expected array
+    const expectedCounts = new SafeMap();
+    for (const expectedItem of expected) {
+      let found = false;
+      for (const { 0: key, 1: count } of expectedCounts) {
+        if (isDeepStrictEqual(key, expectedItem)) {
+          MapPrototypeSet(expectedCounts, key, count + 1);
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        MapPrototypeSet(expectedCounts, expectedItem, 1);
+      }
+    }
+
+    // Create a map to count occurrences of relevant elements in the actual array
+    for (const actualItem of actual) {
+      for (const { 0: key, 1: count } of expectedCounts) {
+        if (isDeepStrictEqual(key, actualItem)) {
+          if (count === 1) {
+            MapPrototypeDelete(expectedCounts, key);
+          } else {
+            MapPrototypeSet(expectedCounts, key, count - 1);
+          }
+          break;
+        }
+      }
+    }
+
+    return !expectedCounts.size;
+  }
+
+  // Comparison done when at least one of the values is not an object
+  if (isSpecial(actual) || isSpecial(expected)) {
+    if (isDeepEqual === undefined) {
+      lazyLoadComparison();
+    }
+    return isDeepStrictEqual(actual, expected);
+  }
+
+  // Use Reflect.ownKeys() instead of Object.keys() to include symbol properties
+  const keysExpected = ReflectOwnKeys(expected);
+
+  comparedObjects ??= new SafeWeakSet();
+
+  // Handle circular references
+  if (comparedObjects.has(actual)) {
+    return true;
+  }
+  comparedObjects.add(actual);
+
+  // Check if all expected keys and values match
+  for (let i = 0; i < keysExpected.length; i++) {
+    const key = keysExpected[i];
+    assert(
+      ReflectHas(actual, key),
+      new AssertionError({ message: `Expected key ${String(key)} not found in actual object` }),
+    );
+    if (!compareBranch(actual[key], expected[key], comparedObjects)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+/**
+ * The strict equivalence assertion test between two objects
+ * @param {any} actual
+ * @param {any} expected
+ * @param {string | Error} [message]
+ * @returns {void}
+ */
+assert.partialDeepStrictEqual = function partialDeepStrictEqual(
+  actual,
+  expected,
+  message,
+) {
+  emitExperimentalWarning('assert.partialDeepStrictEqual');
+  if (arguments.length < 2) {
+    throw new ERR_MISSING_ARGS('actual', 'expected');
+  }
+
+  if (!compareBranch(actual, expected)) {
+    innerFail({
+      actual,
+      expected,
+      message,
+      operator: 'partialDeepStrictEqual',
+      stackStartFn: partialDeepStrictEqual,
+    });
+  }
+};
+
 class Comparison {
   constructor(obj, keys, actual) {
     for (const key of keys) {

lib/internal/test_runner/test.js

@@ -119,6 +119,7 @@ function lazyAssertObject(harness) {
       'notDeepStrictEqual',
       'notEqual',
       'notStrictEqual',
+      'partialDeepStrictEqual',
       'rejects',
       'strictEqual',
       'throws',

test/parallel/test-assert-objects.js

@@ -0,0 +1,501 @@
+'use strict';
+
+const common = require('../common');
+const vm = require('node:vm');
+const assert = require('node:assert');
+const { describe, it } = require('node:test');
+
+function createCircularObject() {
+  const obj = {};
+  obj.self = obj;
+  return obj;
+}
+
+function createDeepNestedObject() {
+  return { level1: { level2: { level3: 'deepValue' } } };
+}
+
+async function generateCryptoKey() {
+  const { KeyObject } = require('node:crypto');
+  const { subtle } = globalThis.crypto;
+
+  const cryptoKey = await subtle.generateKey(
+    {
+      name: 'HMAC',
+      hash: 'SHA-256',
+      length: 256,
+    },
+    true,
+    ['sign', 'verify']
+  );
+
+  const keyObject = KeyObject.from(cryptoKey);
+
+  return { cryptoKey, keyObject };
+}
+
+describe('Object Comparison Tests', () => {
+  describe('partialDeepStrictEqual', () => {
+    describe('throws an error', () => {
+      const tests = [
+        {
+          description: 'throws when only one argument is provided',
+          actual: { a: 1 },
+          expected: undefined,
+        },
+        {
+          description: 'throws when expected has more properties than actual',
+          actual: [1, 'two'],
+          expected: [1, 'two', true],
+        },
+        {
+          description: 'throws because expected has seven 2 while actual has six one',
+          actual: [1, 2, 2, 2, 2, 2, 2, 3],
+          expected: [1, 2, 2, 2, 2, 2, 2, 2],
+        },
+        {
+          description: 'throws when comparing two different sets with objects',
+          actual: new Set([{ a: 1 }]),
+          expected: new Set([{ a: 1 }, { b: 1 }]),
+        },
+
+        {
+          description: 'throws when comparing two WeakSet objects',
+          actual: new WeakSet(),
+          expected: new WeakSet(),
+        },
+        {
+          description: 'throws when comparing two WeakMap objects',
+          actual: new WeakMap(),
+          expected: new WeakMap(),
+        },
+        {
+          description: 'throws when comparing two different objects',
+          actual: { a: 1, b: 'string' },
+          expected: { a: 2, b: 'string' },
+        },
+        {
+          description:
+            'throws when comparing two objects with different nested objects',
+          actual: createDeepNestedObject(),
+          expected: { level1: { level2: { level3: 'differentValue' } } },
+        },
+        {
+          description:
+            'throws when comparing two objects with different RegExp properties',
+          actual: { pattern: /abc/ },
+          expected: { pattern: /def/ },
+        },
+        {
+          description:
+            'throws when comparing two arrays with different elements',
+          actual: [1, 'two', true],
+          expected: [1, 'two', false],
+        },
+        {
+          description:
+            'throws when comparing two Date objects with different times',
+          actual: new Date(0),
+          expected: new Date(1),
+        },
+        {
+          description:
+            'throws when comparing two objects with different large number of properties',
+          actual: Object.fromEntries(
+            Array.from({ length: 100 }, (_, i) => [`key${i}`, i])
+          ),
+          expected: Object.fromEntries(
+            Array.from({ length: 100 }, (_, i) => [`key${i}`, i + 1])
+          ),
+        },
+        {
+          description:
+            'throws when comparing two objects with different Symbols',
+          actual: { [Symbol('test')]: 'symbol' },
+          expected: { [Symbol('test')]: 'symbol' },
+        },
+        {
+          description:
+            'throws when comparing two objects with different array properties',
+          actual: { a: [1, 2, 3] },
+          expected: { a: [1, 2, 4] },
+        },
+        {
+          description:
+            'throws when comparing two objects with different function properties',
+          actual: { fn: () => {} },
+          expected: { fn: () => {} },
+        },
+        {
+          description:
+            'throws when comparing two objects with different Error instances',
+          actual: { error: new Error('Test error 1') },
+          expected: { error: new Error('Test error 2') },
+        },
+        {
+          description:
+            'throws when comparing two objects with different TypedArray instances and content',
+          actual: { typedArray: new Uint8Array([1, 2, 3]) },
+          expected: { typedArray: new Uint8Array([4, 5, 6]) },
+        },
+        {
+          description:
+            'throws when comparing two Map objects with different entries',
+          actual: new Map([
+            ['key1', 'value1'],
+            ['key2', 'value2'],
+          ]),
+          expected: new Map([
+            ['key1', 'value1'],
+            ['key3', 'value3'],
+          ]),
+        },
+        {
+          description:
+            'throws when comparing two Map objects with different keys',
+          actual: new Map([
+            ['key1', 'value1'],
+            ['key2', 'value2'],
+          ]),
+          expected: new Map([
+            ['key1', 'value1'],
+            ['key3', 'value2'],
+          ]),
+        },
+        {
+          description:
+            'throws when comparing two Map objects with different length',
+          actual: new Map([
+            ['key1', 'value1'],
+            ['key2', 'value2'],
+          ]),
+          expected: new Map([['key1', 'value1']]),
+        },
+        {
+          description:
+            'throws when comparing two TypedArray instances with different content',
+          actual: new Uint8Array(10),
+          expected: () => {
+            const typedArray2 = new Int8Array(10);
+            Object.defineProperty(typedArray2, Symbol.toStringTag, {
+              value: 'Uint8Array'
+            });
+            Object.setPrototypeOf(typedArray2, Uint8Array.prototype);
+
+            return typedArray2;
+          },
+        },
+        {
+          description:
+            'throws when comparing two Set objects from different realms with different values',
+          actual: new vm.runInNewContext('new Set(["value1", "value2"])'),
+          expected: new Set(['value1', 'value3']),
+        },
+        {
+          description:
+            'throws when comparing two Set objects with different values',
+          actual: new Set(['value1', 'value2']),
+          expected: new Set(['value1', 'value3']),
+        },
+        {
+          description: 'throws when comparing one subset object with another',
+          actual: { a: 1, b: 2, c: 3 },
+          expected: { b: '2' },
+        },
+        {
+          description: 'throws when comparing one subset array with another',
+          actual: [1, 2, 3],
+          expected: ['2'],
+        },
+      ];
+
+      if (common.hasCrypto) {
+        tests.push({
+          description:
+            'throws when comparing two objects with different CryptoKey instances objects',
+          actual: async () => {
+            return generateCryptoKey();
+          },
+          expected: async () => {
+            return generateCryptoKey();
+          },
+        });
+
+        const { createSecretKey } = require('node:crypto');
+
+        tests.push({
+          description:
+            'throws when comparing two objects with different KeyObject instances objects',
+          actual: createSecretKey(Buffer.alloc(1, 0)),
+          expected: createSecretKey(Buffer.alloc(1, 1)),
+        });
+      }
+
+      tests.forEach(({ description, actual, expected }) => {
+        it(description, () => {
+          assert.throws(() => assert.partialDeepStrictEqual(actual, expected), Error);
+        });
+      });
+    });
+  });
+
+  describe('does not throw an error', () => {
+    const sym = Symbol('test');
+    const func = () => {};
+
+    [
+      {
+        description: 'compares two identical simple objects',
+        actual: { a: 1, b: 'string' },
+        expected: { a: 1, b: 'string' },
+      },
+      {
+        description: 'compares two objects with different property order',
+        actual: { a: 1, b: 'string' },
+        expected: { b: 'string', a: 1 },
+      },
+      {
+        description: 'compares two deeply nested objects with partial equality',
+        actual: { a: { nested: { property: true, some: 'other' } } },
+        expected: { a: { nested: { property: true } } },
+      },
+      {
+        description:
+          'compares plain objects from different realms',
+        actual: vm.runInNewContext(`({
+          a: 1,
+          b: 2n,
+          c: "3",
+          d: /4/,
+          e: new Set([5]),
+          f: [6],
+          g: new Uint8Array()
+        })`),
+        expected: { b: 2n, e: new Set([5]), f: [6], g: new Uint8Array() },
+      },
+      {
+        description: 'compares two integers',
+        actual: 1,
+        expected: 1,
+      },
+      {
+        description: 'compares two strings',
+        actual: '1',
+        expected: '1',
+      },
+      {
+        description: 'compares two objects with nested objects',
+        actual: createDeepNestedObject(),
+        expected: createDeepNestedObject(),
+      },
+      {
+        description: 'compares two objects with circular references',
+        actual: createCircularObject(),
+        expected: createCircularObject(),
+      },
+      {
+        description: 'compares two arrays with identical elements',
+        actual: [1, 'two', true],
+        expected: [1, 'two', true],
+      },
+      {
+        description: 'compares two Date objects with the same time',
+        actual: new Date(0),
+        expected: new Date(0),
+      },
+      {
+        description: 'compares two objects with large number of properties',
+        actual: Object.fromEntries(
+          Array.from({ length: 100 }, (_, i) => [`key${i}`, i])
+        ),
+        expected: Object.fromEntries(
+          Array.from({ length: 100 }, (_, i) => [`key${i}`, i])
+        ),
+      },
+      {
+        description: 'compares two objects with Symbol properties',
+        actual: { [sym]: 'symbol' },
+        expected: { [sym]: 'symbol' },
+      },
+      {
+        description: 'compares two objects with RegExp properties',
+        actual: { pattern: /abc/ },
+        expected: { pattern: /abc/ },
+      },
+      {
+        description: 'compares two objects with identical function properties',
+        actual: { fn: func },
+        expected: { fn: func },
+      },
+      {
+        description: 'compares two objects with mixed types of properties',
+        actual: { num: 1, str: 'test', bool: true, sym },
+        expected: { num: 1, str: 'test', bool: true, sym },
+      },
+      {
+        description: 'compares two objects with Buffers',
+        actual: { buf: Buffer.from('Node.js') },
+        expected: { buf: Buffer.from('Node.js') },
+      },
+      {
+        description: 'compares two objects with identical Error properties',
+        actual: { error: new Error('Test error') },
+        expected: { error: new Error('Test error') },
+      },
+      {
+        description: 'compares two objects with TypedArray instances with the same content',
+        actual: { typedArray: new Uint8Array([1, 2, 3]) },
+        expected: { typedArray: new Uint8Array([1, 2, 3]) },
+      },
+      {
+        description: 'compares two Map objects with identical entries',
+        actual: new Map([
+          ['key1', 'value1'],
+          ['key2', 'value2'],
+        ]),
+        expected: new Map([
+          ['key1', 'value1'],
+          ['key2', 'value2'],
+        ]),
+      },
+      {
+        describe: 'compares two array of objects',
+        actual: [{ a: 5 }],
+        expected: [{ a: 5 }],
+      },
+      {
+        describe: 'compares two array of objects where expected is a subset of actual',
+        actual: [{ a: 5 }, { b: 5 }],
+        expected: [{ a: 5 }],
+      },
+      {
+        description: 'compares two Set objects with identical objects',
+        actual: new Set([{ a: 1 }]),
+        expected: new Set([{ a: 1 }]),
+      },
+      {
+        description: 'compares two Set objects where expected is a subset of actual',
+        actual: new Set([{ a: 1 }, { b: 1 }]),
+        expected: new Set([{ a: 1 }]),
+      },
+      {
+        description: 'compares two Set objects with identical arrays',
+        actual: new Set(['value1', 'value2']),
+        expected: new Set(['value1', 'value2']),
+      },
+      {
+        description: 'compares two Set objects',
+        actual: new Set(['value1', 'value2', 'value3']),
+        expected: new Set(['value1', 'value2']),
+      },
+      {
+        description:
+          'compares two Map objects from different realms with identical entries',
+        actual: new vm.runInNewContext(
+          'new Map([["key1", "value1"], ["key2", "value2"]])'
+        ),
+        expected: new Map([
+          ['key1', 'value1'],
+          ['key2', 'value2'],
+        ]),
+      },
+      {
+        description:
+          'compares two objects with identical getter/setter properties',
+        actual: (() => {
+          let value = 'test';
+          return Object.defineProperty({}, 'prop', {
+            get: () => value,
+            set: (newValue) => {
+              value = newValue;
+            },
+            enumerable: true,
+            configurable: true,
+          });
+        })(),
+        expected: (() => {
+          let value = 'test';
+          return Object.defineProperty({}, 'prop', {
+            get: () => value,
+            set: (newValue) => {
+              value = newValue;
+            },
+            enumerable: true,
+            configurable: true,
+          });
+        })(),
+      },
+      {
+        description: 'compares two objects with no prototype',
+        actual: { __proto__: null, prop: 'value' },
+        expected: { __proto__: null, prop: 'value' },
+      },
+      {
+        description:
+          'compares two objects with identical non-enumerable properties',
+        actual: (() => {
+          const obj = {};
+          Object.defineProperty(obj, 'hidden', {
+            value: 'secret',
+            enumerable: false,
+          });
+          return obj;
+        })(),
+        expected: (() => {
+          const obj = {};
+          Object.defineProperty(obj, 'hidden', {
+            value: 'secret',
+            enumerable: false,
+          });
+          return obj;
+        })(),
+      },
+      {
+        description: 'compares two identical primitives, string',
+        actual: 'foo',
+        expected: 'foo',
+      },
+      {
+        description: 'compares two identical primitives, number',
+        actual: 1,
+        expected: 1,
+      },
+      {
+        description: 'compares two identical primitives, boolean',
+        actual: false,
+        expected: false,
+      },
+      {
+        description: 'compares two identical primitives, null',
+        actual: null,
+        expected: null,
+      },
+      {
+        description: 'compares two identical primitives, undefined',
+        actual: undefined,
+        expected: undefined,
+      },
+      {
+        description: 'compares two identical primitives, Symbol',
+        actual: sym,
+        expected: sym,
+      },
+      {
+        description:
+          'compares one subset object with another',
+        actual: { a: 1, b: 2, c: 3 },
+        expected: { b: 2 },
+      },
+      {
+        description:
+          'compares one subset array with another',
+        actual: [1, 2, 3],
+        expected: [2],
+      },
+    ].forEach(({ description, actual, expected }) => {
+      it(description, () => {
+        assert.partialDeepStrictEqual(actual, expected);
+      });
+    });
+  });
+});