Question

我正尝试在Jest和Enzyme中为我的React App设置一些简单的测试。我正在使用shallow来渲染应用程序的主容器，但是似乎正在渲染子级和下面的所有子级。

  ● Test suite failed to run

    TypeError: Cannot read property 'NaN' of undefined

       7 | export function getRandomColor() {
       8 |      console.log(colors);
    >  9 |      return colorsKeys[Math.floor(Math.random() * colorsLength)];
         |                       ^
      10 | }
      11 |
      12 | export function determineColor(genotype) {

      at getRandomColor (src/utils/determineColor.js:9:19)
      at Object.<anonymous> (src/exampleState.js:10:16)
      at Object.<anonymous> (src/reducers/flowersReducer.js:1:1)
      at Object.<anonymous> (src/reducers/indexReducer.js:2:1)
      at Object.<anonymous> (src/index.js:14:1)
      at Object.<anonymous> (src/utils/determineColor.js:5:1)
      at Object.<anonymous> (src/components/NewFlowerFromPunnettButton.js:4:1)
      at Object.<anonymous> (src/components/Dashboard.js:2:1)
      at Object.<anonymous> (src/App.jsx:6:1)
      at Object.<anonymous> (test/App.test.js:4:1)

每个Enzyme docs“浅表渲染有助于将组件作为一个单元进行测试，并确保您的测试不会间接断言子组件的行为。”

This SO answer似乎澄清了shallow“将呈现其所有子项以及所有子项，依此类推。”


    //App.test.js
    import React from "react";
    // shallow prevents rendering of sub components????
    import { shallow, mount, render } from "enzyme";
    import App from "../src/App";

    describe("<App />", () => {
        const app = shallow(<App />);
        it("Should render ", () => {
            expect(app).toMatchSnapShot();
        });
        it("Should have <Punnett/> <Dashboard/> and <FlowerTable />", () => {
            expect(app.find("<Punnett />")).toBeTruthy();
            expect(app.find("<Dashboard/>")).toBeTruthy();
            expect(app.find("<FlowerTable />")).toBeTruthy();
        });

    });


    //App.jsx
    import React, { Component, Fragment } from "react";

    import "./css/App.css";
    import Punnett from "./components/Punnett";
    import FlowerTable from "./components/FlowerTable/FlowerTable";
    import Dashboard from "./components/Dashboard";

    class App extends Component {
        render() {
            return (
                <Fragment>
                    <div className="App">
                        <Punnett />
                        <Dashboard />
                    </div>
                    <div className="App">
                        <FlowerTable display={true} />
                    </div>
                </Fragment>
            );
        }
    }

    export default App;


    // determineColor.js
    import { colors } from "../types/colors";
    const colorsKeys = Object.keys(colors);
    const colorsLength = colorsKeys.length;

    import { store } from "../index";

    export function getRandomColor() {
        console.log(colors);
        return colorsKeys[Math.floor(Math.random() * colorsLength)];
    }

我期望浅层不能渲染子级，或者如果预期的行为是渲染所有子级，则子级能够正确导入其模块。将shallow换为render会导致相同的错误。

通过在https://github.com/nodes777/flower-game-phaser3上克隆并运行npm run test可以复制

Answer 1

shallow仅渲染子级，这是正确的。根本原因：似乎"./components/Dashboard";内有可以在import上运行的代码-一些执行而不是声明的顶级代码。

您可以更改Dashboard而不这样做，或者提供需要的数据，或者在可能直接或间接导入的每个测试中明确地模拟它：

App.test.js：

jest.mock('./components/Dashboard');

如果您选择以后的方法，则可以考虑通过创建components/Dashboard/__mocks__/index.jsx（或Dashboard中的文件名如何）来进行自动模拟，但是要注意bug in jest，这会禁止您使用多个以上的{{1 }}，无论它们位于不同的文件夹中

酵素的肤浅正在使孩子们的孩子成瘾？

1 个答案: