Mock timers in tests

Mock entire modules

Setup and teardown functions

jest/mock

Create mock functions for testing

jest

mock

functions

const mockFn = jest.fn()

Mock functions allow you to test code in isolation by replacing dependencies with controllable test doubles.

Create mock function

const mockFn = jest.fn()

Mock with return value

const mockFn = jest.fn(() => "mocked value")

Spy on existing function

jest.spyOn(module, "functionName")

Install Jest testing framework

Test asynchronous code

Test component snapshots