Expect Api

mock 函数

mockName

指定mock函数的名字，这在报错的时候非常有用

const myMockFn = jest.fn().mockName('myMockFn');
mockFn.mock.results
指定函数返回值
fn.mock.results = [
        type: 'throw',
        value: {
            /* Error instance */
        type: 'return',
        value: 'result2',
//期待最后一次返回结果为'result2'
expect(fn).toHaveLastReturnedWith( 'result2')
mockFn.mockClear
重置存储在mockFn.mock.calls,mockFn.mock.instances和mockFn.mock.results数组中的所有信息。
fn.mock.results = [
        type: 'return',
        value: 'result2',
fn.mockClear()
//会报错，因为清空了mock
expect(fn).toHaveLastReturnedWith( 'result2')
mockFn.mockReset
执行所有mockFn.mockClear()操作，并删除任何模拟的返回值或实现
const fn = jest.fn()
fn.mock.results = [
        type: 'return',
        value: 'result2',
fn.mockReset()
//完全重置回其初始状态时jest.fn()
expect(fn).not.toReturn()
mockFn.mockImplementation
const mockFn = jest.fn().mockImplementation(scalar => 42 + scalar);
// or: jest.fn(scalar => 42 + scalar);
const a = mockFn(0);
const b = mockFn(1);
a === 42; // true
b === 43; // true
mockFn.mock.calls[0][0] === 0; // true
mockFn.mock.calls[1][0] === 1; // true
mockFn.mockReturnValue
指定返回值
const mock = jest.fn();
mock.mockReturnValue(42);
mock()
expect(mock).toReturnWith(42)
//下面三种方式都可以达到上面的效果
//const mock = jest.fn(()=>42);
//use mockImplementation
//const mock = jest.fn().mockImplementation(()=>42);
//mock.mock.results = [{type:'return',value:42}]
mockFn.mockResolvedValue
模拟成功的回调
test('async test', async () => {
    //const asyncMock = jest.fn(()=> Promise.resolve(42));
    const asyncMock = jest.fn().mockResolvedValue(43);
    await asyncMock(); // 43
mockFn.mockRejectedValue
模拟失败的回调
test('async test', async () => {
    //const asyncMock = jest.fn(()=> Promise.reject(42));
    const asyncMock = jest.fn().mockRejectedValue(43);
    await asyncMock(); // 43
mock Modules
模拟axios
//模拟模块，可以搭配mockResolvedValue和Implementations等api使用
import axios from 'axios';
jest.mock('axios');
//模拟一个文件中部分函数
jest.mock('path', () => {
  const originalModule = jest.requireActual('path');
  return {
    __esModule: true,
    ...originalModule,
    functionName: jest.fn(() => true),
    courage酱
       
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