React-在功能组件中测试外部功能

Question

i具有使用React Hooks的功能组件。我的功能可以更新该组件的状态（ esturefulction ）。

此更新状态函数调用用于检索数据的外部函数，类似的内容：

import { calculatePerformanceTime } from "../../helpers/calculate-performance-time";
const getChallenge = challengeNumber =>
    calculatePerformanceTime(
        require(`../../../challenges/${challengeNumber}.js`)[
            `dcpChallenge${challengeNumber}`
        ],
        challengeNumber
    );
export const TestComponent = _ => {
    const [inputs, setInputs] = useState({});
    const [result, setResult] = useState({});
    const evaluateFunction = value => setResult(getChallenge(value)(inputs));
    return (
        <div>
          <button onClick={() => evaluateFunction(1)} />
        </div>
    );
};

当我单击以测试calculatePerformanceTime是否被调用时，它会给我带来此错误：

TypeError: getChallenge(...) is not a function

我尝试导出 getChallenge ，但它不起作用。

单击按钮时如何测试该功能是否被调用？

这是我到目前为止一直在测试的内容：

import React from "react";
import Adapter from "enzyme-adapter-react-16";
import { configure, shallow } from "enzyme";
import { ChallengeSolution } from "./ChallengeSolution";
import { calculatePerformanceTime } from "../../helpers/calculate-performance-time";
configure({ adapter: new Adapter() });
const mockFunction = jest.fn();
const mockInputData = 1;
jest.mock(`!raw-loader!../../challenges/1.js`, () => "MOCK_RAW", {
    virtual: true
});
jest.mock(`!raw-loader!../../challenges/2.js`, () => "MOCK_RAW", {
    virtual: true
});
jest.mock("../../helpers/calculate-performance-time.js");
describe("ChallengeSolutionComponent", () => {
    let wrapper;
    const tabNumber = 2;
    beforeEach(() => {
        wrapper = shallow(<ChallengeSolution selectedTab={tabNumber} />);
    });
    describe("when component was mount", () => {
        it("should render form correctly", () => {
            const title = wrapper.find(".challenge-solution__title");
            const button = wrapper.find(".challenge-solution__button");
            button.simulate("click");
            expect(calculatePerformanceTime).toHaveBeenCalled();
            expect(title.text()).toEqual(`Daily Coding Solution #${tabNumber}`);
        });
    });
});

Answer 1

此行：

jest.mock("../../helpers/calculate-performance-time.js");

...将calculatePerformanceTime设置为返回undefined的空模拟功能。

由于getChallenge返回调用calculatePerformanceTime的结果，因此它也返回undefined。

然后，当该行运行时：

const evaluateFunction = value => setResult(getChallenge(value)(inputs));

...它试图将getChallenge(...)的结果用作函数并使用inputs调用，但这是失败的，因为它试图将undefined称为函数。

---

您需要模拟calculatePerformanceTime返回函数：

import React from "react";
import Adapter from "enzyme-adapter-react-16";
import { configure, shallow } from "enzyme";
import { ChallengeSolution } from "./ChallengeSolution";
import * as calculatePerformanceTimeModule from "../../helpers/calculate-performance-time";  // import the module
configure({ adapter: new Adapter() });
const mockFunction = jest.fn();
const mockInputData = 1;
jest.mock(`!raw-loader!../../challenges/1.js`, () => "MOCK_RAW", {
  virtual: true
});
jest.mock(`!raw-loader!../../challenges/2.js`, () => "MOCK_RAW", {
  virtual: true
});
const spy = jest.spyOn(calculatePerformanceTimeModule, 'calculatePerformanceTime');
spy.mockReturnValue(() => { /* this returns a function...fill in the return value here */ });
describe("ChallengeSolutionComponent", () => {
  let wrapper;
  const tabNumber = 2;
  beforeEach(() => {
    wrapper = shallow(<ChallengeSolution selectedTab={tabNumber} />);
  });
  describe("when component was mount", () => {
    it("should render form correctly", () => {
      const title = wrapper.find(".challenge-solution__title");
      const button = wrapper.find(".challenge-solution__button");
      button.simulate("click");
      expect(spy).toHaveBeenCalled();  // Success!
      expect(title.text()).toEqual(`Daily Coding Solution #${tabNumber}`);
    });
  });
});