assert.rejects(asyncFn[, error][, message])

• asyncFn <Function> | <Promise>
• error <RegExp> | <Function> | <Object> | <Error>
• message <string>

等待 asyncFn promise，或者，如果 asyncFn 是函数，则立即调用该函数并等待返回的 promise 完成。 然后将检查 promise 是否被拒绝。

如果 asyncFn 是函数并且它同步抛出错误，则 assert.rejects() 将返回使用使用该错误拒绝的 Promise。 如果函数没有返回 promise，则 assert.rejects() 将返回使用 ERR_INVALID_RETURN_VALUE 错误拒绝的 Promise。 在这两种情况下，都会跳过错误句柄。

除了等待完成的异步性质外，其行为与 assert.throws() 相同。

如果指定，则 error 可以是 Class、RegExp、验证函数、每个属性将被测试的对象，或者每个属性（包括不可枚举的 message 和 name 属性）将被测试的错误实例。

如果指定，则 message 将是 AssertionError 提供的消息（如果 asyncFn 没有被拒绝）。

(async () => {
  await assert.rejects(
    async () => {
      throw new TypeError('Wrong value');
    },
    {
      name: 'TypeError',
      message: 'Wrong value'
    }
  );
})();

(async () => {
  await assert.rejects(
    async () => {
      throw new TypeError('Wrong value');
    },
    (err) => {
      assert.strictEqual(err.name, 'TypeError');
      assert.strictEqual(err.message, 'Wrong value');
      return true;
    }
  );
})();

assert.rejects(
  Promise.reject(new Error('Wrong value')),
  Error
).then(() => {
  // ...
});

error 不能是字符串。 如果提供字符串作为第二个参数，则假定 error 被省略，而该字符串将用于 message。 这可能会导致容易遗漏的错误。 如果考虑使用字符串作为第二个参数，则请仔细阅读 assert.throws() 中的示例。

• asyncFn <Function> | <Promise>
• error <RegExp> | <Function> | <Object> | <Error>
• message <string>

Awaits the asyncFn promise or, if asyncFn is a function, immediately calls the function and awaits the returned promise to complete. It will then check that the promise is rejected.

If asyncFn is a function and it throws an error synchronously, assert.rejects() will return a rejected Promise with that error. If the function does not return a promise, assert.rejects() will return a rejected Promise with an ERR_INVALID_RETURN_VALUE error. In both cases the error handler is skipped.

Besides the async nature to await the completion behaves identically to assert.throws().

If specified, error can be a Class, RegExp, a validation function, an object where each property will be tested for, or an instance of error where each property will be tested for including the non-enumerable message and name properties.

If specified, message will be the message provided by the AssertionError if the asyncFn fails to reject.

(async () => {
  await assert.rejects(
    async () => {
      throw new TypeError('Wrong value');
    },
    {
      name: 'TypeError',
      message: 'Wrong value'
    }
  );
})();

(async () => {
  await assert.rejects(
    async () => {
      throw new TypeError('Wrong value');
    },
    (err) => {
      assert.strictEqual(err.name, 'TypeError');
      assert.strictEqual(err.message, 'Wrong value');
      return true;
    }
  );
})();

assert.rejects(
  Promise.reject(new Error('Wrong value')),
  Error
).then(() => {
  // ...
});

error cannot be a string. If a string is provided as the second argument, then error is assumed to be omitted and the string will be used for message instead. This can lead to easy-to-miss mistakes. Please read the example in assert.throws() carefully if using a string as the second argument gets considered.