jest 中不同模拟 API 调用返回不同数据

Question

我开始了解有关使用 Jest 和测试库测试 React 组件的更多信息。我已使用模拟 API 返回用户数据并在测试中呈现它，并希望user_active = true在第一个 API 调用和user_active = false第二个 API 调用中返回。

这是我在模拟文件夹中模拟 getUsers API 的代码：

"use strict";
module.exports = {
  getUsers: () => {
    return Promise.resolve({
      data: {
        id: 27,
        full_name: "john doe",
        username: "jhon",
        is_active: true,
      },
    });
  },
}

这是我的组件，用户信息是一个包含（id、full_name、username、is_active）的对象：

  class Users extends Component {
      constructor(props) {
        super(props);
        this.state = {
          userInfo: null,
        };
      }


  getUsers = () => {
    const token = this.props.token;
    myAPI.getUsers(token)
      .then((res) => {
        this.setState({
          data: res.data,
          error: null,
        });
      })
      .catch((error) => {
        this.setState({
          error: error,
          data: [],
        });
      });
  };

  refreshList = () => {
     this.getUsers();
  };

  render() {
    return (
      <div>
       <a data-testid="refresh-button" onClick = {this.refreshList}>load user data </a>
       <span> {this.state.userInfo.username}</span>
       <span> {this.state.userInfo.is_active}</span>
      </div>
     )
    
  }


}

这是我的测试：

import React from "react";
import { render } from "@testing-library/react";
import "@testing-library/jest-dom/extend-expect";
jest.mock("../MyApi");
import Users from "./index";


  test("load users twice", async () => {
  let baseDom = render(<Users/>);//first API call  
  expect(await baseDom.findByText("true")).toBeInTheDocument();
  fireEvent.click(await baseDom.findByTestId("refresh-button")); //to second api call
  expect(await baseDom.findByText("false")).toBeInTheDocument();
});

如何在第一次/第二次 API 调用中返回不同的数据？

Answer 1

您可以通过使用方法来实现此jest.mockResolvedValueOnce()目的，请查看文档以获取有关该方法如何工作的更多信息。

import React from "react";
import { render } from "@testing-library/react";
import "@testing-library/jest-dom/extend-expect";
import Users from "./index";
import myApi from '../MyApi'


it('should give two different results', () => {
  const firstMockReturn = {
    id: 27,
    full_name: "john doe",
    username: "john",
    is_active: true
  };
  const secondMockReturn = {
    id: 28,
    full_name: "jane doe",
    username: "jane",
    is_active: false
  };
  jest.spyOn(myApi, 'getUsers')
      .mockResolvedValueOnce(firstMockReturn) // will return to firstMockReturn object firstly
      .mockResolvedValueOnce(secondMockReturn); // will return to secondMockReturn object secondly

  let baseDom = render(<Users />)

 
  expect(await baseDom.findByText("true")).toBeInTheDocument();
  fireEvent.click(await baseDom.findByTestId("refresh-button")); //to second api call
  expect(await baseDom.findByText("false")).toBeInTheDocument();


})