柴:是否期望错误取决于参数 [英] Chai: expecting an error or not depending on a parameter

问题描述

我一直在尝试编写处理错误的函数的文本，如果该错误是有效错误，则抛出该错误，但如果不是，则不抛出任何错误.问题是我似乎无法在使用时设置参数:

I've been trying to do a text of a function that handles errors in a way that, if it is a valid error, it is thrown, but if it is not, then nothing is thrown. The problem is that i cant seem to set the parameter while using:

expect(handleError).to.throw(Error);

理想的方法是使用:

expect(handleError(validError)).to.throw(Error);

有什么方法可以实现此功能?

Is there any way to achieve this functionality?

函数代码:

function handleError (err) {
    if (err !== true) {
        switch (err) {
            case xxx:
            ...
        }
        throw "stop js execution";
    else {}
}

以及测试代码(未按预期工作):

And the code of the test (not working as intended):

it("should stop Javascript execution if the parameter isnt \"true\"", function() {
    expect(handleError).to.be.a("function");
    expect(handleError(true)).to.not.throw(Error);
    expect(handleError("anything else")).to.throw(Error);
});

推荐答案

问题是您正在调用handleError，然后将结果传递给期望值.如果handleError抛出，则期望永远不会被调用.

The problem is that you are calling handleError, then passing the result to expect. If handleError throws, then expect never even gets called.

您需要将handleError的调用推迟到调用expected之前，以便Expect可以看到调用该函数时发生的情况.幸运的是，这是期望的:

You need to defer calling handleError until expect is called, so that expect can see what happens when the function is called. Fortunately, this is what expect wants:

expect(function () { handleError(true); }).to.not.throw();
expect(function () { handleError("anything else") }).to.throw("stop js execution");

如果您阅读了文档以进行抛出，则您会看到应该为相关的期望传递一个函数.

If you read the documentation for throw, you'll see that the associated expect should be passed a function.

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