fix: independently mock each instance's methods for mocked class

packages/vitest/src/runtime/mocker.ts

@@ -325,13 +325,36 @@ export class VitestMocker {
  continue
 
  if (isFunction) {
- const spyModule = this.spyModule
- if (!spyModule)
+ if (!this.spyModule)
  throw this.createError('[vitest] `spyModule` is not defined. This is Vitest error. Please open a new issue with reproduction.')
- const mock = spyModule.spyOn(newContainer, property).mockImplementation(() => undefined)
+ const spyModule = this.spyModule
+ const primitives = this.primitives
+ function mockFunction(this: any) {
+ // detect constructor call and mock each instance's methods
+ // so that mock states between prototype/instances don't affect each other
+ // (jest reference https://github.com/jestjs/jest/blob/2c3d2409879952157433de215ae0eee5188a4384/packages/jest-mock/src/index.ts#L678-L691)
+ if (this instanceof newContainer[property]) {
+ for (const { key } of getAllMockableProperties(this, false, primitives)) {
+ const value = this[key]
+ const type = getType(value)
+ const isFunction = type.includes('Function') && typeof value === 'function'
+ if (isFunction) {
+ // mock and delegate calls to original prototype method, which should be also mocked already
+ const original = this[key]
+ const mock = spyModule.spyOn(this, key as string).mockImplementation(original)
+ mock.mockRestore = () => {
+ mock.mockReset()
+ mock.mockImplementation(original)
+ return mock
+ }
+ }
+ }
+ }
+ }
+ const mock = spyModule.spyOn(newContainer, property).mockImplementation(mockFunction)
  mock.mockRestore = () => {
  mock.mockReset()
- mock.mockImplementation(() => undefined)
+ mock.mockImplementation(mockFunction)
  return mock
  }
  // tinyspy retains length, but jest doesn't.

test/core/src/mockedE.ts

@@ -0,0 +1,11 @@
+export const symbolFn = Symbol.for('symbolFn')
+
+export class MockedE {
+ public testFn(arg: string) {
+ return arg.repeat(2)
+ }
+
+ public [symbolFn](arg: string) {
+ return arg.repeat(2)
+ }
+}

test/core/test/mocked-class-restore-all.test.ts

@@ -0,0 +1,78 @@
+import { expect, test, vi } from 'vitest'
+
+import { MockedE } from '../src/mockedE'
+
+vi.mock('../src/mockedE')
+
+test(`mocked class are not affected by restoreAllMocks`, () => {
+ const instance0 = new MockedE()
+ expect(instance0.testFn('a')).toMatchInlineSnapshot(`undefined`)
+ expect(vi.mocked(instance0.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+
+ vi.restoreAllMocks()
+
+ // reset only history after restoreAllMocks
+ expect(instance0.testFn('b')).toMatchInlineSnapshot(`undefined`)
+ expect(vi.mocked(instance0.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+
+ // mocked constructor is still effective after restoreAllMocks
+ const instance1 = new MockedE()
+ const instance2 = new MockedE()
+ expect(instance1).not.toBe(instance2)
+ expect(instance1.testFn).not.toBe(instance2.testFn)
+ expect(instance1.testFn).not.toBe(MockedE.prototype.testFn)
+ expect(vi.mocked(instance1.testFn).mock).not.toBe(vi.mocked(instance2.testFn).mock)
+
+ expect(instance1.testFn('c')).toMatchInlineSnapshot(`undefined`)
+ expect(vi.mocked(instance0.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "c",
+ ],
+ ]
+ `)
+ expect(vi.mocked(instance2.testFn).mock.calls).toMatchInlineSnapshot(`[]`)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ [
+ "c",
+ ],
+ ]
+ `)
+})

test/core/test/mocked-class-restore-explicit.test.ts

@@ -0,0 +1,86 @@
+import { expect, test, vi } from 'vitest'
+
+import { MockedE } from '../src/mockedE'
+
+vi.mock('../src/mockedE')
+
+// this behavior looks odd but jest also doesn't seem to support this use case properly
+test(`mocked class methods are not restorable by explicit mockRestore calls`, () => {
+ const instance1 = new MockedE()
+
+ expect(instance1.testFn('a')).toMatchInlineSnapshot(`undefined`)
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+
+ // restoring instance method
+ vi.mocked(instance1.testFn).mockRestore()
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`[]`)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+
+ expect(instance1.testFn('b')).toMatchInlineSnapshot(`undefined`)
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ [
+ "b",
+ ],
+ ]
+ `)
+
+ // restoring prototype method
+ vi.mocked(MockedE.prototype.testFn).mockRestore()
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`[]`)
+
+ expect(instance1.testFn('c')).toMatchInlineSnapshot(`undefined`)
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ [
+ "c",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "c",
+ ],
+ ]
+ `)
+})

test/core/test/mocked-class.test.ts

@@ -0,0 +1,115 @@
+import { expect, test, vi } from 'vitest'
+
+import { MockedE, symbolFn } from '../src/mockedE'
+
+vi.mock('../src/mockedE')
+
+test(`each instance's methods of mocked class should have independent mock function state`, () => {
+ const instance1 = new MockedE()
+ const instance2 = new MockedE()
+ expect(instance1).not.toBe(instance2)
+ expect(instance1.testFn).not.toBe(instance2.testFn)
+ expect(instance1.testFn).not.toBe(MockedE.prototype.testFn)
+ expect(vi.mocked(instance1.testFn).mock).not.toBe(vi.mocked(instance2.testFn).mock)
+
+ expect(instance1.testFn('a')).toMatchInlineSnapshot(`undefined`)
+ expect(instance1.testFn).toBeCalledTimes(1)
+ expect(instance2.testFn).toBeCalledTimes(0)
+ expect(MockedE.prototype.testFn).toBeCalledTimes(1)
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ ]
+ `)
+
+ expect(instance2.testFn('b')).toMatchInlineSnapshot(`undefined`)
+ expect(instance1.testFn).toBeCalledTimes(1)
+ expect(instance2.testFn).toBeCalledTimes(1)
+ expect(MockedE.prototype.testFn).toBeCalledTimes(2)
+ expect(vi.mocked(instance2.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ [
+ "b",
+ ],
+ ]
+ `)
+
+ expect(instance1.testFn('c')).toMatchInlineSnapshot(`undefined`)
+ expect(instance1.testFn).toBeCalledTimes(2)
+ expect(instance2.testFn).toBeCalledTimes(1)
+ expect(MockedE.prototype.testFn).toBeCalledTimes(3)
+ expect(vi.mocked(instance1.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ [
+ "c",
+ ],
+ ]
+ `)
+ expect(vi.mocked(instance2.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "b",
+ ],
+ ]
+ `)
+ expect(vi.mocked(MockedE.prototype.testFn).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "a",
+ ],
+ [
+ "b",
+ ],
+ [
+ "c",
+ ],
+ ]
+ `)
+
+ // test same things for symbol key method
+ expect(instance1[symbolFn]).not.toBe(instance2[symbolFn])
+ expect(instance1[symbolFn]).not.toBe(MockedE.prototype[symbolFn])
+ expect(vi.mocked(instance1[symbolFn]).mock).not.toBe(vi.mocked(instance2[symbolFn]).mock)
+
+ expect(instance1[symbolFn]('d')).toMatchInlineSnapshot(`undefined`)
+ expect(instance1[symbolFn]).toBeCalledTimes(1)
+ expect(instance2[symbolFn]).toBeCalledTimes(0)
+ expect(MockedE.prototype[symbolFn]).toBeCalledTimes(1)
+ expect(vi.mocked(instance1[symbolFn]).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "d",
+ ],
+ ]
+ `)
+ expect(vi.mocked(instance2[symbolFn]).mock.calls).toMatchInlineSnapshot(`[]`)
+ expect(vi.mocked(MockedE.prototype[symbolFn]).mock.calls).toMatchInlineSnapshot(`
+ [
+ [
+ "d",
+ ],
+ ]
+ `)
+})