README.md

vitest-todo

Mocking Function and Module

How to mock module

full example look useTodo.test.ts

1. to mock module you can use vi.mock('path/to/module', factory) where factory is a function that return all exported member from the module. if you dont provide the factory module, all exported member from the module will undefined. also you can use global mock module using __mocks__ folder in the root folder or alongside the module

   vi.mock('@/modules/axios', () => {
     return {
       http: {
         get: vi.fn().mockResolvedValue({ data: true })
       }
     }
   })

2. use vi.mocked to get the exported mock function from the module that have been mocked. test the exported mocked member using vi.isMockFunction(fn)

   expect(vi.isMockFunction(AxiosModule.http.get)).toBe(true)

3. you can then override the mock function return value, or implementation

   vi.mocked(AxiosModule.http.get).mockImplementationOnce(() => {
     return Promise.resolve({ data: mockAll })
   })

Mock Reset

full example look useManage.spec.ts

After you mock the module, you can use fn().mockReset() to reset the inner implementation to undefined. If you intent to change the implementation you can use this and apply new implementation

1. mock module using vi.mock('path/to/module') then add the exported member

vi.mock('@/libs/useLib', () => ({
  useLib: vi.fn(() => ({
    plus: vi.fn(),
    minus: vi.fn(),
    clear: vi.fn()
  }))
}))

2. reset the mocked module using .mockReset()

const mocked = vi.mocked(useLib, { partial: true }).mockReset()

3. define exported member from the mocked module, since it will return undefined

const spy = vi.fn()
mocked.mockImplementationOnce(() => ({
  clear: vi.fn(),
  minus: spy.mockReturnValueOnce('mocked'),
  plus: vi.fn()
}))