feat: allow extending toEqual (fix #2875)

docs/api/expect.md

@@ -1405,3 +1405,55 @@ Don't forget to include the ambient declaration file in your `tsconfig.json`.
 :::tip
 If you want to know more, checkout [guide on extending matchers](/guide/extending-matchers).
 :::
+
+## expect.addEqualityTesters <Badge type="info">1.2.0+</Badge>
+
+- **Type:** `(tester: Array<Tester>) => void`
+
+You can use this method to define custom testers, which are methods used by matchers, to test if two objects are equal. It is compatible with Jest's `expect.addEqualityTesters`.
+
+```ts
+import { expect, test } from 'vitest'
+
+class AnagramComparator {
+  public word: string
+
+  constructor(word: string) {
+    this.word = word
+  }
+
+  equals(other: AnagramComparator): boolean {
+    const cleanStr1 = this.word.replace(/ /g, '').toLowerCase()
+    const cleanStr2 = other.word.replace(/ /g, '').toLowerCase()
+
+    const sortedStr1 = cleanStr1.split('').sort().join('')
+    const sortedStr2 = cleanStr2.split('').sort().join('')
+
+    return sortedStr1 === sortedStr2
+  }
+}
+
+function isAnagramComparator(a: unknown): a is AnagramComparator {
+  return a instanceof AnagramComparator
+}
+
+function areAnagramsEqual(a: unknown, b: unknown): boolean | undefined {
+  const isAAnagramComparator = isAnagramComparator(a)
+  const isBAnagramComparator = isAnagramComparator(b)
+
+  if (isAAnagramComparator && isBAnagramComparator)
+    return a.equals(b)
+
+  else if (isAAnagramComparator === isBAnagramComparator)
+    return undefined
+
+  else
+    return false
+}
+
+expect.addEqualityTesters([areAnagramsEqual])
+
+test('custom equality tester', () => {
+  expect(new AnagramComparator('listen')).toEqual(new AnagramComparator('silent'))
+})
+```

examples/vitesse/src/auto-import.d.ts

@@ -62,4 +62,5 @@ declare global {
 declare global {
   // @ts-ignore
   export type { Component, ComponentPublicInstance, ComputedRef, InjectionKey, PropType, Ref, VNode } from 'vue'
-}
+  export type { Component, ComponentPublicInstance, ComputedRef, ExtractDefaultPropTypes, ExtractPropTypes, ExtractPublicPropTypes, InjectionKey, PropType, Ref, VNode, WritableComputedRef } from 'vue'
+}

packages/expect/src/index.ts

@@ -4,5 +4,6 @@ export * from './constants'
 export * from './types'
 export { getState, setState } from './state'
 export { JestChaiExpect } from './jest-expect'
+export { addCustomEqualityTesters } from './jest-matcher-utils'
 export { JestExtend } from './jest-extend'
 export { setupColors } from '@vitest/utils'

packages/expect/src/jest-asymmetric-matchers.ts

@@ -1,7 +1,7 @@
 import type { ChaiPlugin, MatcherState } from './types'
 import { GLOBAL_EXPECT } from './constants'
 import { getState } from './state'
-import { diff, getMatcherUtils, stringify } from './jest-matcher-utils'
+import { diff, getCustomEqualityTesters, getMatcherUtils, stringify } from './jest-matcher-utils'
 
 import { equals, isA, iterableEquality, pluralize, subsetEquality } from './jest-utils'
 
@@ -26,7 +26,7 @@ export abstract class AsymmetricMatcher<
       ...getState(expect || (globalThis as any)[GLOBAL_EXPECT]),
       equals,
       isNot: this.inverse,
-      customTesters: [],
+      customTesters: getCustomEqualityTesters(),
       utils: {
         ...getMatcherUtils(),
         diff,
@@ -116,8 +116,9 @@ export class ObjectContaining extends AsymmetricMatcher<Record<string, unknown>>
 
     let result = true
 
+    const matcherContext = this.getMatcherContext()
     for (const property in this.sample) {
-      if (!this.hasProperty(other, property) || !equals(this.sample[property], other[property])) {
+      if (!this.hasProperty(other, property) || !equals(this.sample[property], other[property], matcherContext.customTesters)) {
         result = false
         break
       }
@@ -149,11 +150,12 @@ export class ArrayContaining<T = unknown> extends AsymmetricMatcher<Array<T>> {
       )
     }
 
+    const matcherContext = this.getMatcherContext()
     const result
       = this.sample.length === 0
       || (Array.isArray(other)
         && this.sample.every(item =>
-          other.some(another => equals(item, another)),
+          other.some(another => equals(item, another, matcherContext.customTesters)),
         ))
 
     return this.inverse ? !result : result

packages/expect/src/jest-expect.ts

@@ -6,7 +6,7 @@ import type { Test } from '@vitest/runner'
 import type { Assertion, ChaiPlugin } from './types'
 import { arrayBufferEquality, generateToBeMessage, iterableEquality, equals as jestEquals, sparseArrayEquality, subsetEquality, typeEquality } from './jest-utils'
 import type { AsymmetricMatcher } from './jest-asymmetric-matchers'
-import { diff, stringify } from './jest-matcher-utils'
+import { diff, getCustomEqualityTesters, stringify } from './jest-matcher-utils'
 import { JEST_MATCHERS_OBJECT } from './constants'
 import { recordAsyncExpect, wrapSoft } from './utils'
 
@@ -23,6 +23,7 @@ declare class DOMTokenList {
 export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
   const { AssertionError } = chai
   const c = () => getColors()
+  const customTesters = getCustomEqualityTesters()
 
   function def(name: keyof Assertion | (keyof Assertion)[], fn: ((this: Chai.AssertionStatic & Assertion, ...args: any[]) => any)) {
     const addMethod = (n: keyof Assertion) => {
@@ -80,7 +81,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
     const equal = jestEquals(
       actual,
       expected,
-      [iterableEquality],
+      [...customTesters, iterableEquality],
     )
 
     return this.assert(
@@ -98,6 +99,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
       obj,
       expected,
       [
+        ...customTesters,
         iterableEquality,
         typeEquality,
         sparseArrayEquality,
@@ -125,6 +127,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
         actual,
         expected,
         [
+          ...customTesters,
           iterableEquality,
           typeEquality,
           sparseArrayEquality,
@@ -140,7 +143,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
         const toEqualPass = jestEquals(
           actual,
           expected,
-          [iterableEquality],
+          [...customTesters, iterableEquality],
         )
 
         if (toEqualPass)
@@ -159,7 +162,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
   def('toMatchObject', function (expected) {
     const actual = this._obj
     return this.assert(
-      jestEquals(actual, expected, [iterableEquality, subsetEquality]),
+      jestEquals(actual, expected, [...customTesters, iterableEquality, subsetEquality]),
       'expected #{this} to match object #{exp}',
       'expected #{this} to not match object #{exp}',
       expected,
@@ -208,7 +211,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
   def('toContainEqual', function (expected) {
     const obj = utils.flag(this, 'object')
     const index = Array.from(obj).findIndex((item) => {
-      return jestEquals(item, expected)
+      return jestEquals(item, expected, customTesters)
     })
 
     this.assert(
@@ -339,7 +342,7 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
       return utils.getPathInfo(actual, propertyName)
     }
     const { value, exists } = getValue()
-    const pass = exists && (args.length === 1 || jestEquals(expected, value))
+    const pass = exists && (args.length === 1 || jestEquals(expected, value, customTesters))
 
     const valueString = args.length === 1 ? '' : ` with value ${utils.objDisplay(expected)}`
 

packages/expect/src/jest-extend.ts

@@ -10,7 +10,7 @@ import { ASYMMETRIC_MATCHERS_OBJECT, JEST_MATCHERS_OBJECT } from './constants'
 import { AsymmetricMatcher } from './jest-asymmetric-matchers'
 import { getState } from './state'
 
-import { diff, getMatcherUtils, stringify } from './jest-matcher-utils'
+import { diff, getCustomEqualityTesters, getMatcherUtils, stringify } from './jest-matcher-utils'
 
 import {
   equals,
@@ -33,8 +33,7 @@ function getMatcherState(assertion: Chai.AssertionStatic & Chai.Assertion, expec
 
   const matcherState: MatcherState = {
     ...getState(expect),
-    // TODO: implement via expect.addEqualityTesters
-    customTesters: [],
+    customTesters: getCustomEqualityTesters(),
     isNot,
     utils: jestUtils,
     promise,

packages/expect/src/jest-matcher-utils.ts

@@ -1,5 +1,6 @@
-import { getColors, stringify } from '@vitest/utils'
-import type { MatcherHintOptions } from './types'
+import { getColors, getType, stringify } from '@vitest/utils'
+import type { MatcherHintOptions, Tester } from './types'
+import { JEST_MATCHERS_OBJECT } from './constants'
 
 export { diff } from '@vitest/utils/diff'
 export { stringify }
@@ -101,3 +102,21 @@ export function getMatcherUtils() {
     printExpected,
   }
 }
+
+export function addCustomEqualityTesters(newTesters: Array<Tester>): void {
+  if (!Array.isArray(newTesters)) {
+    throw new TypeError(
+      `expect.customEqualityTesters: Must be set to an array of Testers. Was given "${getType(
+        newTesters,
+      )}"`,
+    )
+  }
+
+  (globalThis as any)[JEST_MATCHERS_OBJECT].customEqualityTesters.push(
+    ...newTesters,
+  )
+}
+
+export function getCustomEqualityTesters(): Array<Tester> {
+  return (globalThis as any)[JEST_MATCHERS_OBJECT].customEqualityTesters
+}

packages/expect/src/jest-utils.ts

@@ -23,7 +23,7 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 
 import { isObject } from '@vitest/utils'
-import type { Tester } from './types'
+import type { Tester, TesterContext } from './types'
 
 // Extracted out of jasmine 2.5.2
 export function equals(
@@ -87,8 +87,9 @@ function eq(
   if (asymmetricResult !== undefined)
     return asymmetricResult
 
+  const testerContext: TesterContext = { equals }
   for (let i = 0; i < customTesters.length; i++) {
-    const customTesterResult = customTesters[i](a, b)
+    const customTesterResult = customTesters[i].call(testerContext, a, b, customTesters)
     if (customTesterResult !== undefined)
       return customTesterResult
   }
@@ -298,7 +299,7 @@ function hasIterator(object: any) {
   return !!(object != null && object[IteratorSymbol])
 }
 
-export function iterableEquality(a: any, b: any, aStack: Array<any> = [], bStack: Array<any> = []): boolean | undefined {
+export function iterableEquality(a: any, b: any, customTesters: Array<Tester> = [], aStack: Array<any> = [], bStack: Array<any> = []): boolean | undefined {
   if (
     typeof a !== 'object'
     || typeof b !== 'object'
@@ -324,7 +325,20 @@ export function iterableEquality(a: any, b: any, aStack: Array<any> = [], bStack
   aStack.push(a)
   bStack.push(b)
 
-  const iterableEqualityWithStack = (a: any, b: any) => iterableEquality(a, b, [...aStack], [...bStack])
+  const filteredCustomTesters: Array<Tester> = [
+    ...customTesters.filter(t => t !== iterableEquality),
+    iterableEqualityWithStack,
+  ]
+
+  function iterableEqualityWithStack(a: any, b: any) {
+    return iterableEquality(
+      a,
+      b,
+      [...filteredCustomTesters],
+      [...aStack],
+      [...bStack],
+    )
+  }
 
   if (a.size !== undefined) {
     if (a.size !== b.size) {
@@ -336,7 +350,7 @@ export function iterableEquality(a: any, b: any, aStack: Array<any> = [], bStack
         if (!b.has(aValue)) {
           let has = false
           for (const bValue of b) {
-            const isEqual = equals(aValue, bValue, [iterableEqualityWithStack])
+            const isEqual = equals(aValue, bValue, filteredCustomTesters)
             if (isEqual === true)
               has = true
           }
@@ -357,20 +371,16 @@ export function iterableEquality(a: any, b: any, aStack: Array<any> = [], bStack
       for (const aEntry of a) {
         if (
           !b.has(aEntry[0])
-          || !equals(aEntry[1], b.get(aEntry[0]), [iterableEqualityWithStack])
+          || !equals(aEntry[1], b.get(aEntry[0]), filteredCustomTesters)
         ) {
           let has = false
           for (const bEntry of b) {
-            const matchedKey = equals(aEntry[0], bEntry[0], [
-              iterableEqualityWithStack,
-            ])
+            const matchedKey = equals(aEntry[0], bEntry[0], filteredCustomTesters)
 
             let matchedValue = false
-            if (matchedKey === true) {
-              matchedValue = equals(aEntry[1], bEntry[1], [
-                iterableEqualityWithStack,
-              ])
-            }
+            if (matchedKey === true)
+              matchedValue = equals(aEntry[1], bEntry[1], filteredCustomTesters)
+
             if (matchedValue === true)
               has = true
           }
@@ -394,7 +404,7 @@ export function iterableEquality(a: any, b: any, aStack: Array<any> = [], bStack
     const nextB = bIterator.next()
     if (
       nextB.done
-      || !equals(aValue, nextB.value, [iterableEqualityWithStack])
+      || !equals(aValue, nextB.value, filteredCustomTesters)
     )
       return false
   }
@@ -430,7 +440,8 @@ function isObjectWithKeys(a: any) {
   && !(a instanceof Date)
 }
 
-export function subsetEquality(object: unknown, subset: unknown): boolean | undefined {
+export function subsetEquality(object: unknown, subset: unknown, customTesters: Array<Tester> = []): boolean | undefined {
+  const filteredCustomTesters = customTesters.filter(t => t !== subsetEquality)
   // subsetEquality needs to keep track of the references
   // it has already visited to avoid infinite loops in case
   // there are circular references in the subset passed to it.
@@ -443,15 +454,15 @@ export function subsetEquality(object: unknown, subset: unknown): boolean | unde
         return Object.keys(subset).every((key) => {
           if (isObjectWithKeys(subset[key])) {
             if (seenReferences.has(subset[key]))
-              return equals(object[key], subset[key], [iterableEquality])
+              return equals(object[key], subset[key], filteredCustomTesters)
 
             seenReferences.set(subset[key], true)
           }
           const result
             = object != null
             && hasPropertyInObject(object, key)
             && equals(object[key], subset[key], [
-              iterableEquality,
+              ...filteredCustomTesters,
               subsetEqualityWithContext(seenReferences),
             ])
           // The main goal of using seenReference is to avoid circular node on tree.
@@ -504,15 +515,16 @@ export function arrayBufferEquality(a: unknown, b: unknown): boolean | undefined
   return true
 }
 
-export function sparseArrayEquality(a: unknown, b: unknown): boolean | undefined {
+export function sparseArrayEquality(a: unknown, b: unknown, customTesters: Array<Tester> = []): boolean | undefined {
   if (!Array.isArray(a) || !Array.isArray(b))
     return undefined
 
   // A sparse array [, , 1] will have keys ["2"] whereas [undefined, undefined, 1] will have keys ["0", "1", "2"]
   const aKeys = Object.keys(a)
   const bKeys = Object.keys(b)
+  const filteredCustomTesters = customTesters.filter(t => t !== sparseArrayEquality)
   return (
-    equals(a, b, [iterableEquality, typeEquality], true) && equals(aKeys, bKeys)
+    equals(a, b, filteredCustomTesters, true) && equals(aKeys, bKeys)
   )
 }