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assert: adjust loose assertions
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This changes the loose deep equal comparison by using the same logic
as done in the strict deep equal comparison besides comparing
primitives loosely and not comparing symbol properties.

`assert.deepEqual` is still commenly used and this is likely the
biggest pitfall.

Most changes are only minor and won't have a big impact besides
likely fixing user expectations.
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@BridgeAR
BridgeAR committed Dec 28, 2018
1 parent 7a867b8 commit b175618
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47 changes: 31 additions & 16 deletions doc/api/assert.md
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Original file line number Diff line number Diff line change
Expand Up @@ -163,6 +163,10 @@ An alias of [`assert.ok()`][].
<!-- YAML
added: v0.1.21
changes:
- version: REPLACEME
pr-url: https://github.com/nodejs/node/pull/REPLACEME
description: The type tags are now properly compared and a couple minor
comparison adjustments to make the check less surprising.
- version: v9.0.0
pr-url: https://github.com/nodejs/node/pull/15001
description: The `Error` names and messages are now properly compared
Expand Down Expand Up @@ -191,26 +195,39 @@ An alias of [`assert.deepStrictEqual()`][].

> Stability: 0 - Deprecated: Use [`assert.deepStrictEqual()`][] instead.
Tests for deep equality between the `actual` and `expected` parameters.
Primitive values are compared with the [Abstract Equality Comparison][]
( `==` ).
Tests for deep equality between the `actual` and `expected` parameters. Consider
using [`assert.deepStrictEqual()`][] instead. [`assert.deepEqual()`][] can have
potentially surprising results.

"Deep" equality means that the enumerable "own" properties of child objects
are recursively evaluated also by the following rules.

### Comparison details

* Primitive values are compared with the [Abstract Equality Comparison][]
( `==` ).
* [Type tags][Object.prototype.toString()] of objects should be the same.
* Only [enumerable "own" properties][] are considered.
* [`Error`][] names and messages are always compared, even if these are not
enumerable properties.
* [Object wrappers][] are compared both as objects and unwrapped values.
* `Object` properties are compared unordered.
* `Map` keys and `Set` items are compared unordered.
* Recursion stops when both sides differ or both sides encounter a circular
reference.
* Implementation does not test the [`[[Prototype]]`][prototype-spec] of
objects.
* [`Symbol`][] properties are not compared.
* [`WeakMap`][] and [`WeakSet`][] comparison does not rely on their values.

Only [enumerable "own" properties][] are considered. The
[`assert.deepEqual()`][] implementation does not test the
[`[[Prototype]]`][prototype-spec] of objects or enumerable own [`Symbol`][]
properties. For such checks, consider using [`assert.deepStrictEqual()`][]
instead. [`assert.deepEqual()`][] can have potentially surprising results. The
following example does not throw an `AssertionError` because the properties on
the [`RegExp`][] object are not enumerable:
The following example does not throw an `AssertionError` because the primitives
are considered equal by the [Abstract Equality Comparison][] ( `==` ).

```js
// WARNING: This does not throw an AssertionError!
assert.deepEqual(/a/gi, new Date());
assert.deepEqual('+00000000', false);
```

An exception is made for [`Map`][] and [`Set`][]. `Map`s and `Set`s have their
contained items compared too, as expected.

"Deep" equality means that the enumerable "own" properties of child objects
are evaluated also:

Expand Down Expand Up @@ -1249,10 +1266,8 @@ second argument. This might lead to difficult-to-spot errors.
[`ERR_INVALID_RETURN_VALUE`]: errors.html#errors_err_invalid_return_value
[`Error.captureStackTrace`]: errors.html#errors_error_capturestacktrace_targetobject_constructoropt
[`Error`]: errors.html#errors_class_error
[`Map`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map
[`Object.is()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is
[`RegExp`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
[`Set`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set
[`Symbol`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol
[`TypeError`]: errors.html#errors_class_typeerror
[`WeakMap`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap
Expand Down
153 changes: 47 additions & 106 deletions lib/internal/util/comparisons.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,9 @@ const {
isStringObject,
isBooleanObject,
isBigIntObject,
isSymbolObject
isSymbolObject,
isFloat32Array,
isFloat64Array
} = require('internal/util/types');
const {
getOwnNonIndexProperties,
Expand Down Expand Up @@ -84,18 +86,6 @@ function areEqualArrayBuffers(buf1, buf2) {
compare(new Uint8Array(buf1), new Uint8Array(buf2)) === 0;
}

function isFloatTypedArrayTag(tag) {
return tag === '[object Float32Array]' || tag === '[object Float64Array]';
}

function isArguments(tag) {
return tag === '[object Arguments]';
}

function isObjectOrArrayTag(tag) {
return tag === '[object Array]' || tag === '[object Object]';
}

function isEqualBoxedPrimitive(val1, val2) {
if (isNumberObject(val1)) {
return isNumberObject(val2) &&
Expand Down Expand Up @@ -132,23 +122,45 @@ function isEqualBoxedPrimitive(val1, val2) {
// For strict comparison, objects should have
// a) The same built-in type tags
// b) The same prototypes.
function strictDeepEqual(val1, val2, memos) {
if (typeof val1 !== 'object') {
return typeof val1 === 'number' && numberIsNaN(val1) &&
numberIsNaN(val2);

function innerDeepEqual(val1, val2, strict, memos) {
// All identical values are equivalent, as determined by ===.
if (val1 === val2) {
if (val1 !== 0)
return true;
return strict ? objectIs(val1, val2) : true;
}
if (typeof val2 !== 'object' || val1 === null || val2 === null) {
return false;

// Check more closely if val1 and val2 are equal.
if (strict) {
if (typeof val1 !== 'object') {
return typeof val1 === 'number' && numberIsNaN(val1) &&
numberIsNaN(val2);
}
if (typeof val2 !== 'object' || val1 === null || val2 === null) {
return false;
}
if (getPrototypeOf(val1) !== getPrototypeOf(val2)) {
return false;
}
} else {
if (val1 === null || typeof val1 !== 'object') {
if (val2 === null || typeof val2 !== 'object') {
// eslint-disable-next-line eqeqeq
return val1 == val2;
}
return false;
}
if (val2 === null || typeof val2 !== 'object') {
return false;
}
}
const val1Tag = objectToString(val1);
const val2Tag = objectToString(val2);

if (val1Tag !== val2Tag) {
return false;
}
if (getPrototypeOf(val1) !== getPrototypeOf(val2)) {
return false;
}
if (Array.isArray(val1)) {
// Check for sparse arrays and general fast path
if (val1.length !== val2.length) {
Expand All @@ -159,10 +171,10 @@ function strictDeepEqual(val1, val2, memos) {
if (keys1.length !== keys2.length) {
return false;
}
return keyCheck(val1, val2, kStrict, memos, kIsArray, keys1);
return keyCheck(val1, val2, strict, memos, kIsArray, keys1);
}
if (val1Tag === '[object Object]') {
return keyCheck(val1, val2, kStrict, memos, kNoIterator);
return keyCheck(val1, val2, strict, memos, kNoIterator);
}
if (isDate(val1)) {
if (dateGetTime(val1) !== dateGetTime(val2)) {
Expand All @@ -174,13 +186,16 @@ function strictDeepEqual(val1, val2, memos) {
}
} else if (isNativeError(val1) || val1 instanceof Error) {
// Do not compare the stack as it might differ even though the error itself
// is otherwise identical. The non-enumerable name should be identical as
// the prototype is also identical. Otherwise this is caught later on.
if (val1.message !== val2.message) {
// is otherwise identical.
if (val1.message !== val2.message || val1.name !== val2.name) {
return false;
}
} else if (isArrayBufferView(val1)) {
if (!areSimilarTypedArrays(val1, val2)) {
if (!strict && (isFloat32Array(val1) || isFloat64Array(val1))) {
if (!areSimilarFloatArrays(val1, val2)) {
return false;
}
} else if (!areSimilarTypedArrays(val1, val2)) {
return false;
}
// Buffer.compare returns true, so val1.length === val2.length. If they both
Expand All @@ -191,84 +206,25 @@ function strictDeepEqual(val1, val2, memos) {
if (keys1.length !== keys2.length) {
return false;
}
return keyCheck(val1, val2, kStrict, memos, kNoIterator, keys1);
return keyCheck(val1, val2, strict, memos, kNoIterator, keys1);
} else if (isSet(val1)) {
if (!isSet(val2) || val1.size !== val2.size) {
return false;
}
return keyCheck(val1, val2, kStrict, memos, kIsSet);
return keyCheck(val1, val2, strict, memos, kIsSet);
} else if (isMap(val1)) {
if (!isMap(val2) || val1.size !== val2.size) {
return false;
}
return keyCheck(val1, val2, kStrict, memos, kIsMap);
return keyCheck(val1, val2, strict, memos, kIsMap);
} else if (isAnyArrayBuffer(val1)) {
if (!areEqualArrayBuffers(val1, val2)) {
return false;
}
} else if (isBoxedPrimitive(val1) && !isEqualBoxedPrimitive(val1, val2)) {
return false;
}
return keyCheck(val1, val2, kStrict, memos, kNoIterator);
}

function looseDeepEqual(val1, val2, memos) {
if (val1 === null || typeof val1 !== 'object') {
if (val2 === null || typeof val2 !== 'object') {
// eslint-disable-next-line eqeqeq
return val1 == val2;
}
return false;
}
if (val2 === null || typeof val2 !== 'object') {
return false;
}
const val1Tag = objectToString(val1);
const val2Tag = objectToString(val2);
if (val1Tag === val2Tag) {
if (isObjectOrArrayTag(val1Tag)) {
return keyCheck(val1, val2, kLoose, memos, kNoIterator);
}
if (isArrayBufferView(val1)) {
if (isFloatTypedArrayTag(val1Tag)) {
return areSimilarFloatArrays(val1, val2);
}
return areSimilarTypedArrays(val1, val2);
}
if (isDate(val1) && isDate(val2)) {
return val1.getTime() === val2.getTime();
}
if (isRegExp(val1) && isRegExp(val2)) {
return areSimilarRegExps(val1, val2);
}
if (val1 instanceof Error && val2 instanceof Error) {
if (val1.message !== val2.message || val1.name !== val2.name)
return false;
}
// Ensure reflexivity of deepEqual with `arguments` objects.
// See https://github.com/nodejs/node-v0.x-archive/pull/7178
} else if (isArguments(val1Tag) || isArguments(val2Tag)) {
return false;
}
if (isSet(val1)) {
if (!isSet(val2) || val1.size !== val2.size) {
return false;
}
return keyCheck(val1, val2, kLoose, memos, kIsSet);
} else if (isMap(val1)) {
if (!isMap(val2) || val1.size !== val2.size) {
return false;
}
return keyCheck(val1, val2, kLoose, memos, kIsMap);
} else if (isSet(val2) || isMap(val2)) {
return false;
}
if (isAnyArrayBuffer(val1) && isAnyArrayBuffer(val2)) {
if (!areEqualArrayBuffers(val1, val2)) {
return false;
}
}
return keyCheck(val1, val2, kLoose, memos, kNoIterator);
return keyCheck(val1, val2, strict, memos, kNoIterator);
}

function getEnumerables(val, keys) {
Expand Down Expand Up @@ -370,21 +326,6 @@ function keyCheck(val1, val2, strict, memos, iterationType, aKeys) {
return areEq;
}

function innerDeepEqual(val1, val2, strict, memos) {
// All identical values are equivalent, as determined by ===.
if (val1 === val2) {
if (val1 !== 0)
return true;
return strict ? objectIs(val1, val2) : true;
}

// Check more closely if val1 and val2 are equal.
if (strict === true)
return strictDeepEqual(val1, val2, memos);

return looseDeepEqual(val1, val2, memos);
}

function setHasEqualElement(set, val1, strict, memo) {
// Go looking.
for (const val2 of set) {
Expand Down
9 changes: 6 additions & 3 deletions test/es-module/test-esm-dynamic-import.js
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Original file line number Diff line number Diff line change
Expand Up @@ -23,9 +23,12 @@ function expectMissingModuleError(result) {
function expectOkNamespace(result) {
Promise.resolve(result)
.then(common.mustCall((ns) => {
// Can't deepStrictEqual because ns isn't a normal object
// eslint-disable-next-line no-restricted-properties
assert.deepEqual(ns, { default: true });
const expected = { default: true };
Object.defineProperty(expected, Symbol.toStringTag, {
value: 'Module'
});
Object.setPrototypeOf(expected, Object.getPrototypeOf(ns));
assert.deepStrictEqual(ns, expected);
}));
}

Expand Down
8 changes: 4 additions & 4 deletions test/parallel/test-assert-checktag.js
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,8 @@ if (process.stdout.isTTY)
FakeDate.prototype = Date.prototype;
const fake = new FakeDate();

assert.deepEqual(date, fake);
assert.deepEqual(fake, date);
assert.notDeepEqual(date, fake);
assert.notDeepEqual(fake, date);

// For deepStrictEqual we check the runtime type,
// then reveal the fakeness of the fake date
Expand All @@ -45,7 +45,7 @@ if (process.stdout.isTTY)
for (const prop of Object.keys(global)) {
fakeGlobal[prop] = global[prop];
}
assert.deepEqual(fakeGlobal, global);
assert.notDeepEqual(fakeGlobal, global);
// Message will be truncated anyway, don't validate
assert.throws(() => assert.deepStrictEqual(fakeGlobal, global),
assert.AssertionError);
Expand All @@ -57,7 +57,7 @@ if (process.stdout.isTTY)
for (const prop of Object.keys(process)) {
fakeProcess[prop] = process[prop];
}
assert.deepEqual(fakeProcess, process);
assert.notDeepEqual(fakeProcess, process);
// Message will be truncated anyway, don't validate
assert.throws(() => assert.deepStrictEqual(fakeProcess, process),
assert.AssertionError);
Expand Down
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