Javascript 按照承诺用 Chai 测试拒绝
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Test a rejection with Chai as promised
提问by Guid
I want to test a function returning a promise.
我想测试一个返回承诺的函数。
In this particular test, the promise is expected to be rejected with an Error object containing the classical messagefield (in this test, it is expected to equal "my error message") and a custom field I added named code, which is a string (like "EACCESS", "ERIGHT", etc, in this test it is expected to equal "EFOO")
在这个特定的测试中，promise 预计会被一个包含经典message字段的 Error 对象（在这个测试中，它应该等于"my error message"）和一个我添加的自定义字段命名为code，它是一个字符串（如“EACCESS”，“ ERIGHT”等，在这个测试中它预计等于"EFOO"）
I want to use chai-as-promised for that.
我想为此使用 chai-as-promised。
return expect(foo()).to.eventually.be.rejectedWith("my error message");
This assertion is working but now I would like to test the codefield too.
How to do that?
这个断言是有效的，但现在我也想测试这个code领域。
怎么做？
回答by Keithamus
If you're using Chai-As-Promised(as you say you are), then it allows for chaining off of rejectedWith- and it sets the chain assertion object to be the error object - meaning anything after rejectedWith()is now going to assert on the Error. This lets you do cool things like:
如果您使用的是Chai-As-Promised（正如您所说的那样），那么它允许链接rejectedWith- 并将链断言对象设置为错误对象 - 意味着之后的任何rejectedWith()内容现在都将在错误上断言. 这让你可以做很酷的事情，比如：
return expect(foo()).to.eventually
.be.rejectedWith("my error message")
.and.be.an.instanceOf(Error)
.and.have.property('code', 'EFOO');
Some of the chai methods also chain, so you can use that to make some quite deeply nested assertions about the error:
一些 chai 方法也是链式的，因此您可以使用它来对错误进行一些非常深入的嵌套断言：
return expect(foo()).to.eventually
.be.rejectedWith("my error message")
.and.have.property('stack')
.that.includes('myfile.js:30')
回答by Markko Paas
Having version 5.1.0 of ChaiAsPromised, solution from Keithamus did not work for me - rejectedWith did not gave me the error object to assert, but "rejected" did:
拥有 ChaiAsPromised 的 5.1.0 版本，来自 Keithamus 的解决方案对我不起作用-rejectedWith 没有给我断言的错误对象，但“拒绝”做了：
return expect(foo())
.to.be.rejected
.and.be.an.instanceOf(Error)
.and.have.property('code', 'EFOO');
For asserting multiple properties
用于断言多个属性
return expect(foo())
.to.be.rejected
.then(function(error) {
expect(error).to.have.property('name', 'my error message');
expect(error).to.have.property('code', 'EFOO');
});
回答by SifouTifou
@Markko Paas's solution didn't work for me until I added 'eventually', or else rejected value is always {} empty object.
@Markko Paas 的解决方案在我添加“最终”之前对我不起作用，否则拒绝的值总是 {} 空对象。
return expect(foo())
.to.eventually.be.rejected
.and.be.an.instanceOf(Error)
.and.have.property('code', 'EFOO');
回答by Rich Apodaca
You can perform complex tests on errors using rejected.then:
您可以使用rejected.then以下方法对错误执行复杂的测试：
it('throws a complex error', function () {
return expect(foo()).to.eventually.be.rejected.then((error) => {
expect(error.code).to.equal('expected code');
// other tests
// alternatively,
expect (error).to.eql({
foo: 'foo',
bar: 'bar
});
});
});
