我正在尝试为Jasmine测试框架编写一个测试,该测试预计会出现错误。目前,我正在使用来自GitHub的Jasmine Node.js集成。
在我的Node.js模块中,我有以下代码:
throw new Error("Parsing is not possible");
现在我试着写一个测试,期望这个错误:
describe('my suite...', function() {
[..]
it('should not parse foo', function() {
[..]
expect(parser.parse(raw)).toThrow(new Error("Parsing is not possible"));
});
});
我还尝试了Error()和其他一些变体,只是不知道如何使它工作。
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;
};