JEST Received 函数没有抛出，但是抛出了 HTTPError [英] JEST Received function did not throw, but HTTPError is thrown

问题描述

我正在使用 JEST 和 Got 测试端点.我预计会出现 403 Forbidden 错误.下面的代码从 catch 块打印错误并且失败，相同的调用没有抛出错误.为什么?

I am testing an endpoint with JEST and Got. I expect 403 Forbidden error. The following code prints the error from catch block AND fails that the identical call does not throw an error. Why?

    try {
        response = await api(`verify/${profile.auth.verifyToken}`, {method: 'POST'}).json();
    } catch (e) {
        console.log(e);
    }
    expect(async () => {
        response = await api(`verify/${profile.auth.verifyToken}`, {method: 'POST'}).json();
    }).toThrow();

输出:

console.log test/api.int.test.js:112
HTTPError: Response code 403 (Forbidden)
    at EventEmitter.<anonymous> (C:devmezinamiridiciinfrastructure
ode_modulesgotdistsourceas-promise.js:118:31)
    at processTicksAndRejections (internal/process/task_queues.js:97:5) {
  name: 'HTTPError'
}


Error: expect(received).toThrow()
Received function did not throw

这个变体也不起作用:

expect(() => api(`verify/${profile.auth.verifyToken}`, {method: 'POST'})).toThrow();

顺便说一句，当 HTTPError 被抛出但未被捕获时，没有堆栈跟踪，我看不到错误在哪里抛出.如果还有其他错误，我会确切地看到哪个测试线是负责的.为什么?

Btw when the HTTPError is thrown and not catched, there is no stacktrace and I do not see where the error was thrown. If there are other error I exactly see which test line was responsible. Why?

推荐答案

expect(...).toThrow() 用于检查函数调用是否抛出错误.调用异步函数时，它永远不会抛出错误；相反，它返回一个 Promise，它可能最终被拒绝".尽管异步函数使用相同的 throw/catch 术语，但检测抛出错误所需的代码与检测被拒绝 Promise 所需的代码不同.这就是 Jest 需要不同断言技术的原因.

expect(...).toThrow() is for checking if an error is thrown from a function call. When calling an async function, it never throws an error; rather it returns a Promise which may eventually become "rejected." Although async functions use the same throw/catch terminology, the code required to detect a thrown error differs from what's required to detect a rejected Promise. This is why Jest needs a different assertion technique.

尝试 expect(...).rejects.toThrow() 代替:

Try expect(...).rejects.toThrow() instead:

await expect(() => api(`verify/${profile.auth.verifyToken}`, {method: 'POST'}).json())
  .rejects.toThrow();

注意你必须await这个断言，因为Jest需要等到Promise完成后才能看到它是解决了还是拒绝了.

Notice you have to await this assertion because Jest needs to wait until the Promise finalizes before seeing whether it resolved or rejected.

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