抛出错误，但 Jest 的 `toThrow()` 没有捕获错误

Question

这是我的错误代码：

 FAIL  build/__test__/FuncOps.CheckFunctionExistenceByString.test.js
  ● 
    expect(CheckFunctionExistenceByStr(
      'any string', 'FunctionThatDoesNotExistsInString'
    )).toThrow();


    Function FunctionThatDoesNotExistsInString does not exists in string.

      at CheckFunctionExistenceByStr (build/FuncOps.js:35:15)
      at Object.<anonymous> (build/__test__/FuncOps.CheckFunctionExistenceByString.test.js:12:51)
          at new Promise (<anonymous>)
          at <anonymous>

如您所见，确实发生了错误：Function FunctionThatDoesNotExistsInString does not exists in string.。但是，它不会在 Jest 中被捕获为传递。

这是我的代码：

test(`
    expect(CheckFunctionExistenceByStr(
      'any string', 'FunctionThatDoesNotExistsInString'
    )).toThrow();
  `, () => {
    expect(CheckFunctionExistenceByStr(
      'any string', 'FunctionThatDoesNotExistsInString'
    )).toThrow();
  }
);

Answer 1

expect(fn).toThrow() 需要一个函数 fn，在调用时会引发异常。

但是，您立即调用CheckFunctionExistenceByStr，这会导致函数在运行断言之前抛出。

替换

test(`
    expect(CheckFunctionExistenceByStr(
      'any string', 'FunctionThatDoesNotExistsInString'
    )).toThrow();
  `, () => {
    expect(CheckFunctionExistenceByStr(
      'any string', 'FunctionThatDoesNotExistsInString'
    )).toThrow();
  }
);

与

test(`
    expect(() => {
      CheckFunctionExistenceByStr(
        'any string', 'FunctionThatDoesNotExistsInString'
      )
    }).toThrow();
  `, () => {
    expect(() => {
      CheckFunctionExistenceByStr(
        'any string', 'FunctionThatDoesNotExistsInString'
      )
    }).toThrow();
  }
);

Answer 2

是的，这只是 Jest 很奇怪。而不是这样做：

expect(youFunction(args)).toThrow(ErrorTypeOrErrorMessage)

这样做：

expect(() => youFunction(args)).toThrow(ErrorTypeOrErrorMessage)