一个比创建一个匿名函数(其唯一目的是包装另一个函数)更优雅的解决方案是使用ES5的bind函数。bind函数创建一个新函数，在调用该函数时，将其this关键字设置为所提供的值，并在调用新函数时所提供的任何参数之前设置给定的参数序列。

而不是:

Expect (function(){解析器。解析(原始配置);})。toThrow(“解析不可能”);

考虑:

期望(parser.parse。绑定(解析器，原始，配置))。toThrow(“解析不可能”);

绑定语法允许您测试具有不同this值的函数，在我看来，这使测试更具可读性。参见:

Jasmine的toThrow匹配器要求参数被包装在匿名函数中吗?

您正在使用:

expect(fn).toThrow(e)

但是如果你看一下函数注释(expected is string):

294 /**
295  * Matcher that checks that the expected exception was thrown by the actual.
296  *
297  * @param {String} expected
298  */
299 jasmine.Matchers.prototype.toThrow = function(expected) {

我想你应该这样写(使用lambda - anonymous函数):

expect(function() { parser.parse(raw); } ).toThrow("Parsing is not possible");

下面的例子证实了这一点:

expect(function () {throw new Error("Parsing is not possible")}).toThrow("Parsing is not possible");

Douglas Crockford强烈推荐这种方法，而不是使用“throw new Error()”(原型):

throw {
   name: "Error",
   message: "Parsing is not possible"
}

我用下面的代码替换了Jasmine的toThrow匹配器，它允许您匹配异常的name属性或其message属性。对我来说，这使得测试更容易编写，也不那么脆弱，因为我可以做到以下几点:

throw {
   name: "NoActionProvided",
   message: "Please specify an 'action' property when configuring the action map."
}

然后用下面的方法进行测试:

expect (function () {
   .. do something
}).toThrow ("NoActionProvided");

这让我可以稍后在不中断测试的情况下调整异常消息，而重要的是它抛出了预期的异常类型。

这是toThrow的替代物，允许这样做:

jasmine.Matchers.prototype.toThrow = function(expected) {
  var result = false;
  var exception;
  if (typeof this.actual != 'function') {
    throw new Error('Actual is not a function');
  }
  try {
    this.actual();
  } catch (e) {
    exception = e;
  }
  if (exception) {
      result = (expected === jasmine.undefined || this.env.equals_(exception.message || exception, expected.message || expected) || this.env.equals_(exception.name, expected));
  }

  var not = this.isNot ? "not " : "";

  this.message = function() {
    if (exception && (expected === jasmine.undefined || !this.env.equals_(exception.message || exception, expected.message || expected))) {
      return ["Expected function " + not + "to throw", expected ? expected.name || expected.message || expected : " an exception", ", but it threw", exception.name || exception.message || exception].join(' ');
    } else {
      return "Expected function to throw an exception.";
    }
  };

  return result;
};

在我的例子中，抛出错误的函数是异步的，所以我遵循了这一点:

await expectAsync(asyncFunction()).toBeRejected();
await expectAsync(asyncFunction()).toBeRejectedWithError(...);

我知道这是更多的代码，但你也可以这样做:

try
    Do something
    @fail Error("should send a Exception")
catch e
    expect(e.name).toBe "BLA_ERROR"
    expect(e.message).toBe 'Message'

it('it should fail', async () => {
    expect.assertions(1);

    try {
        await testInstance.doSomething();
    }
    catch (ex) {
        expect(ex).toBeInstanceOf(MyCustomError);
    }
});