beforeEach([, fn][, options])

• fn <Function> | <AsyncFunction> 钩子函数。 如果钩子使用回调，则回调函数作为第二个参数传入。 默认值: 无操作的函数。
• options <Object> 钩子的配置选项。 支持以下属性：
  • signal <AbortSignal> 允许中止正在进行的钩子。
  • timeout <number> 钩子会在几毫秒后失败。 如果未指定，则子测试从其父测试继承此值。 默认值: Infinity。

此函数用于创建一个在当前套件的每个子测试之前运行的钩子。

describe('tests', async () => {
  beforeEach(() => t.diagnostic('about to run a test'));
  it('is a subtest', () => {
    assert.ok('some relevant assertion here');
  });
});

• fn <Function> | <AsyncFunction> The hook function. If the hook uses callbacks, the callback function is passed as the second argument. Default: A no-op function.
• options <Object> Configuration options for the hook. The following properties are supported:
  • signal <AbortSignal> Allows aborting an in-progress hook.
  • timeout <number> A number of milliseconds the hook will fail after. If unspecified, subtests inherit this value from their parent. Default: Infinity.

This function is used to create a hook running before each subtest of the current suite.

describe('tests', async () => {
  beforeEach(() => t.diagnostic('about to run a test'));
  it('is a subtest', () => {
    assert.ok('some relevant assertion here');
  });
});