如何在玩笑测试中共享设置和拆卸? [英] How do I share setup and teardown in jest tests?

问题描述

我发现反应测试食谱非常冗长，因为它们需要设置一个容器，并在每次测试后进行清理.

I've found react tests recipes quite verbose, because they need to setup a container and cleanup that after each test.

我想在需要但无法找到方法的测试文件之间共享该安装拆卸代码，并且我不想在每个组件测试中都重复beforeEach和afterEach.

I would like to share that setup-teardown code between test files that require that but could not find a way to do it and I would prefer not to repeat beforeEach and afterEach on every component test.

我已经尝试过类似的事情:

I've tried with something like:

# sample.test.js

#...
import container from './react_helpers.js'
#...

# react_helpers.js

import { unmountComponentAtNode } from "react-dom"

let container = null;

beforeEach(() => {
  // setup a DOM element as a render target
  container = document.createElement("div");
  document.body.appendChild(container);
});

afterEach(() => {
  // cleanup on exiting
  unmountComponentAtNode(container);
  container.remove();
  container = null;
});

export default container

但是似乎beforeEach并未运行.

But it seems that beforeEach is not being run.

推荐答案

react_helpers出现问题.如果未使用导入，则不会评估ES模块，因此，如果以下未引用container，则import container from './react_helpers.js'将是空操作.而且ES模块仅在首次导入时进行评估，因此它们可能不适合此任务.

There are problems with react_helpers. ES modules aren't evaluated if imports aren't in use so import container from './react_helpers.js' will be a no-op if container isn't referenced below. And ES modules are evaluated only on first import, so they may be not suitable for this task.

如果需要共享数据，则需要在commonSetup和评估它的上下文之间共享一个公共对象，例如

In case there's a need to share data, a common objects need to be shared between commonSetup and the context where it's evaluated, like explained here:

export default function commonSetup(context = {}) {
  beforeEach(() => {
    context.container = ...;
    ...
  });
  afterEach(...);

  return context;
}

然后可以在需要此设置的测试中导入commonSetup并对其进行评估:

Then commonSetup can be imported and evaluated in tests that need this setup:

import commonSetup from './react_helpers.js'

...

let context = commonSetup();

it('...', () => {
  let { container } = context;
  ...
});

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