feat: remove unrelated noise from diff for toMatchObject() (#5364)

Author: geersch

packages/expect/src/jest-expect.ts

@@ -4,7 +4,7 @@ import type { MockInstance } from '@vitest/spy'
 import { isMockFunction } from '@vitest/spy'
 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 { arrayBufferEquality, generateToBeMessage, getObjectSubset, iterableEquality, equals as jestEquals, sparseArrayEquality, subsetEquality, typeEquality } from './jest-utils'
 import type { AsymmetricMatcher } from './jest-asymmetric-matchers'
 import { diff, getCustomEqualityTesters, stringify } from './jest-matcher-utils'
 import { JEST_MATCHERS_OBJECT } from './constants'
@@ -161,13 +161,23 @@ export const JestChaiExpect: ChaiPlugin = (chai, utils) => {
   })
   def('toMatchObject', function (expected) {
     const actual = this._obj
-    return this.assert(
-      jestEquals(actual, expected, [...customTesters, iterableEquality, subsetEquality]),
-      'expected #{this} to match object #{exp}',
-      'expected #{this} to not match object #{exp}',
-      expected,
-      actual,
+    const pass = jestEquals(actual, expected, [...customTesters, iterableEquality, subsetEquality])
+    const isNot = utils.flag(this, 'negate') as boolean
+    const { subset: actualSubset, stripped } = getObjectSubset(actual, expected)
+    const msg = utils.getMessage(
+      this,
+      [
+        pass,
+        'expected #{this} to match object #{exp}',
+        'expected #{this} to not match object #{exp}',
+        expected,
+        actualSubset,
+      ],
     )
+    if ((pass && isNot) || (!pass && !isNot)) {
+      const message = stripped === 0 ? msg : `${msg}\n(${stripped} matching ${stripped === 1 ? 'property' : 'properties'} omitted from actual)`
+      throw new AssertionError(message, { showDiff: true, expected, actual: actualSubset })
+    }
   })
   def('toMatch', function (expected: string | RegExp) {
     const actual = this._obj as string

packages/expect/src/jest-utils.ts

@@ -420,7 +420,7 @@ export function iterableEquality(a: any, b: any, customTesters: Array<Tester> =
 /**
  * Checks if `hasOwnProperty(object, key)` up the prototype chain, stopping at `Object.prototype`.
  */
-function hasPropertyInObject(object: object, key: string): boolean {
+function hasPropertyInObject(object: object, key: string | symbol): boolean {
   const shouldTerminate
     = !object || typeof object !== 'object' || object === Object.prototype
 
@@ -540,3 +540,69 @@ export function generateToBeMessage(deepEqualityName: string, expected = '#{this
 export function pluralize(word: string, count: number): string {
   return `${count} ${word}${count === 1 ? '' : 's'}`
 }
+
+export function getObjectKeys(object: object): Array<string | symbol> {
+  return [
+    ...Object.keys(object),
+    ...Object.getOwnPropertySymbols(object).filter(
+      s => Object.getOwnPropertyDescriptor(object, s)?.enumerable,
+    ),
+  ]
+}
+
+export function getObjectSubset(object: any, subset: any, customTesters: Array<Tester> = []): { subset: any; stripped: number } {
+  let stripped = 0
+
+  const getObjectSubsetWithContext = (seenReferences: WeakMap<object, boolean> = new WeakMap()) => (object: any, subset: any): any => {
+    if (Array.isArray(object)) {
+      if (Array.isArray(subset) && subset.length === object.length) {
+        // The map method returns correct subclass of subset.
+        return subset.map((sub: any, i: number) =>
+          getObjectSubsetWithContext(seenReferences)(object[i], sub),
+        )
+      }
+    }
+    else if (object instanceof Date) {
+      return object
+    }
+    else if (isObject(object) && isObject(subset)) {
+      if (
+        equals(object, subset, [
+          ...customTesters,
+          iterableEquality,
+          subsetEquality,
+        ])
+      ) {
+        // Avoid unnecessary copy which might return Object instead of subclass.
+        return subset
+      }
+
+      const trimmed: any = {}
+      seenReferences.set(object, trimmed)
+
+      for (const key of getObjectKeys(object)) {
+        if (hasPropertyInObject(subset, key)) {
+          trimmed[key] = seenReferences.has(object[key])
+            ? seenReferences.get(object[key])
+            : getObjectSubsetWithContext(seenReferences)(object[key], subset[key])
+        }
+        else {
+          if (!seenReferences.has(object[key])) {
+            stripped += 1
+            if (isObject(object[key]))
+              stripped += getObjectKeys(object[key]).length
+
+            getObjectSubsetWithContext(seenReferences)(object[key], subset[key])
+          }
+        }
+      }
+
+      if (getObjectKeys(trimmed).length > 0)
+        return trimmed
+    }
+
+    return object
+  }
+
+  return { subset: getObjectSubsetWithContext()(object, subset), stripped }
+}

test/core/test/jest-expect.test.ts

@@ -903,24 +903,152 @@ it('correctly prints diff with asymmetric matchers', () => {
   }
 })
 
-it('toHaveProperty error diff', () => {
-  setupColors(getDefaultColors())
+// make it easy for dev who trims trailing whitespace on IDE
+function trim(s: string): string {
+  return s.replaceAll(/ *$/gm, '')
+}
 
-  // make it easy for dev who trims trailing whitespace on IDE
-  function trim(s: string): string {
-    return s.replaceAll(/ *$/gm, '')
+function getError(f: () => unknown) {
+  try {
+    f()
+    return expect.unreachable()
   }
-
-  function getError(f: () => unknown) {
-    try {
-      f()
-      return expect.unreachable()
-    }
-    catch (error) {
-      const processed = processError(error)
-      return [processed.message, trim(processed.diff)]
-    }
+  catch (error) {
+    const processed = processError(error)
+    return [processed.message, trim(processed.diff)]
   }
+}
+
+it('toMatchObject error diff', () => {
+  setupColors(getDefaultColors())
+
+  // single property on root (3 total properties, 1 expected)
+  expect(getError(() => expect({ a: 1, b: 2, c: 3 }).toMatchObject({ c: 4 }))).toMatchInlineSnapshot(`
+    [
+      "expected { a: 1, b: 2, c: 3 } to match object { c: 4 }
+    (2 matching properties omitted from actual)",
+      "- Expected
+    + Received
+
+      Object {
+    -   "c": 4,
+    +   "c": 3,
+      }",
+    ]
+  `)
+
+  // single property on root (4 total properties, 1 expected)
+  expect(getError(() => expect({ a: 1, b: 2, c: { d: 4 } }).toMatchObject({ b: 3 }))).toMatchInlineSnapshot(`
+    [
+      "expected { a: 1, b: 2, c: { d: 4 } } to match object { b: 3 }
+    (3 matching properties omitted from actual)",
+      "- Expected
+    + Received
+
+      Object {
+    -   "b": 3,
+    +   "b": 2,
+      }",
+    ]
+  `)
+
+  // nested property (7 total properties, 2 expected)
+  expect(getError(() => expect({ a: 1, b: 2, c: { d: 4, e: 5 }, f: { g: 6 } }).toMatchObject({ c: { d: 5 } }))).toMatchInlineSnapshot(`
+    [
+      "expected { a: 1, b: 2, c: { d: 4, e: 5 }, …(1) } to match object { c: { d: 5 } }
+    (5 matching properties omitted from actual)",
+      "- Expected
+    + Received
+
+      Object {
+        "c": Object {
+    -     "d": 5,
+    +     "d": 4,
+        },
+      }",
+    ]
+  `)
+
+  // 3 total properties, 3 expected (0 stripped)
+  expect(getError(() => expect({ a: 1, b: 2, c: 3 }).toMatchObject({ a: 1, b: 2, c: 4 }))).toMatchInlineSnapshot(`
+    [
+      "expected { a: 1, b: 2, c: 3 } to match object { a: 1, b: 2, c: 4 }",
+      "- Expected
+    + Received
+
+      Object {
+        "a": 1,
+        "b": 2,
+    -   "c": 4,
+    +   "c": 3,
+      }",
+    ]
+  `)
+
+  // 4 total properties, 3 expected
+  expect(getError(() => expect({ a: 1, b: 2, c: { d: 3 } }).toMatchObject({ a: 1, c: { d: 4 } }))).toMatchInlineSnapshot(`
+    [
+      "expected { a: 1, b: 2, c: { d: 3 } } to match object { a: 1, c: { d: 4 } }
+    (1 matching property omitted from actual)",
+      "- Expected
+    + Received
+
+      Object {
+        "a": 1,
+        "c": Object {
+    -     "d": 4,
+    +     "d": 3,
+        },
+      }",
+    ]
+  `)
+
+  // 8 total properties, 4 expected
+  expect(getError(() => expect({ a: 1, b: 2, c: { d: 4 }, foo: { value: 'bar' }, bar: { value: 'foo' } }).toMatchObject({ c: { d: 5 }, foo: { value: 'biz' } }))).toMatchInlineSnapshot(`
+    [
+      "expected { a: 1, b: 2, c: { d: 4 }, …(2) } to match object { c: { d: 5 }, foo: { value: 'biz' } }
+    (4 matching properties omitted from actual)",
+      "- Expected
+    + Received
+
+      Object {
+        "c": Object {
+    -     "d": 5,
+    +     "d": 4,
+        },
+        "foo": Object {
+    -     "value": "biz",
+    +     "value": "bar",
+        },
+      }",
+    ]
+  `)
+
+  // 8 total properties, 3 expected
+  const characters = { firstName: 'Vladimir', lastName: 'Harkonnen', family: 'House Harkonnen', colors: ['red', 'blue'], children: [{ firstName: 'Jessica', lastName: 'Atreides', colors: ['red', 'green', 'black'] }] }
+  expect(getError(() => expect(characters).toMatchObject({ family: 'House Atreides', children: [{ firstName: 'Paul' }] }))).toMatchInlineSnapshot(`
+    [
+      "expected { firstName: 'Vladimir', …(4) } to match object { family: 'House Atreides', …(1) }
+    (5 matching properties omitted from actual)",
+      "- Expected
+    + Received
+
+      Object {
+        "children": Array [
+          Object {
+    -       "firstName": "Paul",
+    +       "firstName": "Jessica",
+          },
+        ],
+    -   "family": "House Atreides",
+    +   "family": "House Harkonnen",
+      }",
+    ]
+  `)
+})
+
+it('toHaveProperty error diff', () => {
+  setupColors(getDefaultColors())
 
   // non match value
   expect(getError(() => expect({ name: 'foo' }).toHaveProperty('name', 'bar'))).toMatchInlineSnapshot(`