blocks|key|535213|text|异步测试在失败的expect()操作上生成一个异常，it()无法捕获该异常，因为该异常被抛出在it()的作用域之外。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|535214|显示的捕获异常是使用node下的process.on('uncaughtException')或浏览器中的window.onerror()捕获的。|535215|要解决此问题，您需要在setTimeout()调用的异步函数中捕获异常，以便以异常作为第一个参数调用done()。您还需要调用不带参数的done()来表示成功，否则mocha将报告一个超时错误，因为您的测试函数永远不会发出已完成的信号：|535216|window.expect+=+chai.expect;

describe(+'my+test',+function()+{
++it(+'should+do+something',+function+(+done+)+{
++++//+done()+is+provided+by+it()+to+indicate+asynchronous+completion
++++//+call+done()+with+no+parameter+to+indicate+that+it()+is+done()+and+successful
++++//+or+with+an+error+to+indicate+that+it()+failed
++++setTimeout(+function+()+{
++++++//+Called+from+the+event+loop,+not+it()
++++++//+So+only+the+event+loop+could+capture+uncaught+exceptions+from+here
++++++try+{
++++++++expect(+true+).to.equal(+false+);
++++++++done();+//+success:+call+done+with+no+parameter+to+indicate+that+it()+is+done()
++++++}+catch(+e+)+{
++++++++done(+e+);+//+failure:+call+done+with+an+error+Object+to+indicate+that+it()+failed
++++++}
++++},+100+);
++++//+returns+immediately+after+setting+timeout
++++//+so+it()+can+no+longer+catch+exception+happening+asynchronously
++}
}|code-block|syntax|javascript|535217|在所有测试用例上这样做既烦人又不干练，因此您可能希望提供一个函数来为您完成此操作。让我们将此函数称为check()|535218|function+check(+done,+f+)+{
++try+{
++++f();
++++done();
++}+catch(+e+)+{
++++done(+e+);
++}
}|535219|使用check()，您现在可以重写异步测试，如下所示：|535220|window.expect+=+chai.expect;

describe(+'my+test',+function()+{
++it(+'should+do+something',+function(+done+)+{
++++setTimeout(+function+()+{
++++++check(+done,+function()+{
++++++++expect(+true+).to.equal(+false+);
++++++}+);
++++},+100+);
++}
}|535221|entityMap^0|8|8|Q|4|1B|4|0|G|V|1H|G|0|B|C|1E|6|1W|6|0|0|1E|7|0|0|2|7|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]|$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|15|8|@$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1A|8|@$9|1B|A|1C|B|C]|$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]]|D|@]|E|$]]|$1|J|3|K|5|L|7|1H|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1I|8|@$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|Q|3|R|5|L|7|1L|8|@]|D|@]|E|$M|N]]|$1|S|3|T|5|6|7|1M|8|@$9|1N|A|1O|B|C]]|D|@]|E|$]]|$1|U|3|V|5|L|7|1P|8|@]|D|@]|E|$M|N]]|$1|W|3|-4|5|6|7|1Q|8|@]|D|@]|E|$]]]|X|$]]

Your asynchronous test generates an exception, on failed <code>expect()</code>ations, that cannot be captured by <code>it()</code> because the exception is thrown outside of <code>it()</code>'s scope.

The captured exception that you see displayed is captured using <code>process.on('uncaughtException')</code> under node or using <code>window.onerror()</code> in the browser. 

To fix this issue, you need to capture the exception within the asynchronous function called by <code>setTimeout()</code> in order to call <code>done()</code> with the exception as the first parameter. You also need to call <code>done()</code> with no parameter to indicate success, otherwise mocha would report a timeout error because your test function would never have signaled that it was done:

<pre><code>window.expect = chai.expect;

describe( 'my test', function() {
 it( 'should do something', function ( done ) {
 // done() is provided by it() to indicate asynchronous completion
 // call done() with no parameter to indicate that it() is done() and successful
 // or with an error to indicate that it() failed
 setTimeout( function () {
 // Called from the event loop, not it()
 // So only the event loop could capture uncaught exceptions from here
 try {
 expect( true ).to.equal( false );
 done(); // success: call done with no parameter to indicate that it() is done()
 } catch( e ) {
 done( e ); // failure: call done with an error Object to indicate that it() failed
 }
 }, 100 );
 // returns immediately after setting timeout
 // so it() can no longer catch exception happening asynchronously
 }
}
</code></pre>

Doing so on all your test cases is annoying and not DRY so you might want to provide a function to do this for you. Let's call this function <code>check()</code>:

<pre><code>function check( done, f ) {
 try {
 f();
 done();
 } catch( e ) {
 done( e );
 }
}
</code></pre>

With <code>check()</code> you can now rewrite your asynchronous tests as follows:

<pre><code>window.expect = chai.expect;

describe( 'my test', function() {
 it( 'should do something', function( done ) {
 setTimeout( function () {
 check( done, function() {
 expect( true ).to.equal( false );
 } );
 }, 100 );
 }
}
</code></pre>

blocks|key|535256|text|如果你喜欢promised，试试Chai+as+Promised+%2B+Q，它允许这样的东西：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|535257|doSomethingAsync().should.eventually.equal("foo").notify(done);|code-block|syntax|javascript|535258|entityMap|0|LINK|mutability|MUTABLE|url|http://chaijs.com/plugins/chai-as-promised|1|https://github.com/kriskowal/q^0|G|G|0|Z|1|1|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]|$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]|Q|$5|L|M|N|C|$O|R]]]]

If you like promised, try <a href="http://chaijs.com/plugins/chai-as-promised">Chai as Promised</a> + <a href="https://github.com/kriskowal/q">Q</a>, which allow something like this:

<pre><code>doSomethingAsync().should.eventually.equal("foo").notify(done);
</code></pre>

blocks|key|535326|text|对我来说，icm+Mocha+/+Chai工作得很好的是来自Sinon图书馆的fakeTimer。只需在必要时提前测试中的计时器即可。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|535327|var+sinon+=+require('sinon');
clock+=+sinon.useFakeTimers();
//+Do+whatever.+
clock.tick(+30000+);+//+Advances+the+JS+clock+30+seconds.|code-block|syntax|javascript|535328|有一个额外的好处，让测试更快地完成。|535329|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

What worked very well for me icm Mocha / Chai was the fakeTimer from Sinon's Library.
Just advance the timer in the test where necessary.

<pre><code>var sinon = require('sinon');
clock = sinon.useFakeTimers();
// Do whatever. 
clock.tick( 30000 ); // Advances the JS clock 30 seconds.
</code></pre>

Has the added bonus of having the test complete quicker.

blocks|key|318450|text|我已经发布了一个包来解决这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|318451|首先安装check-chai包：|offset|length|style|CODE|318452|npm+install+--save+check-chai|318453|然后在测试中使用chai.use(checkChai);，然后使用chai.check助手函数，如下所示：|318454|var+chai+=+require('chai');
var+dirtyChai+=+require('dirty-chai');
var+checkChai+=+require('check-chai');
var+expect+=+chai.expect;
chai.use(dirtyChai);
chai.use(checkChai);

describe('test',+function()+{

++it('should+do+something',+function(done)+{

++++//+imagine+you+have+some+API+call+here
++++//+and+it+returns+(err,+res,+body)
++++var+err+=+null;
++++var+res+=+{};
++++var+body+=+{};

++++chai.check(done,+function()+{
++++++expect(err).to.be.a('null');
++++++expect(res).to.be.an('object');
++++++expect(body).to.be.an('object');
++++});

++});

});|code-block|syntax|javascript|318455|根据Is+there+a+way+to+get+Chai+working+with+asynchronous+Mocha+tests?，我将其作为NPM包发布。|318456|请查看https://github.com/niftylettuce/check-chai了解更多信息。|318457|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/11235815/is-there-a-way-to-get-chai-working-with-asynchronous-mocha-tests/15208067#comment55687475_15208067|1|https://github.com/niftylettuce/check-chai^0|0|4|A|0|0|T|0|8|K|X|A|0|0|2|1T|0|0|3|16|1|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@$D|16|E|17|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|18|8|@$D|19|E|1A|F|G]]|9|@]|A|$]]|$1|J|3|K|5|6|7|1B|8|@$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]]|9|@]|A|$]]|$1|L|3|M|5|N|7|1G|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|1H|8|@]|9|@$D|1I|E|1J|1|1K]]|A|$]]|$1|S|3|T|5|6|7|1L|8|@]|9|@$D|1M|E|1N|1|1O]]|A|$]]|$1|U|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]|12|$5|X|Y|Z|A|$10|13]]]]

I've published a package that resolves this issue.

First install the <code>check-chai</code> package:

<code>npm install --save check-chai</code>

Then in your tests, use <code>chai.use(checkChai);</code> and then use the <code>chai.check</code> helper function as shown below:

<pre><code>var chai = require('chai');
var dirtyChai = require('dirty-chai');
var checkChai = require('check-chai');
var expect = chai.expect;
chai.use(dirtyChai);
chai.use(checkChai);

describe('test', function() {

 it('should do something', function(done) {

 // imagine you have some API call here
 // and it returns (err, res, body)
 var err = null;
 var res = {};
 var body = {};

 chai.check(done, function() {
 expect(err).to.be.a('null');
 expect(res).to.be.an('object');
 expect(body).to.be.an('object');
 });

 });

});
</code></pre>

Per <a href="https://stackoverflow.com/questions/11235815/is-there-a-way-to-get-chai-working-with-asynchronous-mocha-tests/15208067#comment55687475_15208067">Is there a way to get Chai working with asynchronous Mocha tests?</a> I published this as an NPM package.

Please see <a href="https://github.com/niftylettuce/check-chai" rel="nofollow">https://github.com/niftylettuce/check-chai</a> for more information.

blocks|key|318509|text|以下是我对ES6/ES2015+promises和ES7/ES2016+async/await的通过测试。希望这篇文章能为任何研究这个话题的人提供一个很好的更新答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|318510|import+{+expect+}+from+'chai'

describe('Mocha',+()+=>+{
++it('works+synchronously',+()+=>+{
++++expect(true).to.equal(true)
++})

++it('works+ansyncronously',+done+=>+{
++++setTimeout(()+=>+{
++++++expect(true).to.equal(true)
++++++done()
++++},+4)
++})

++it('throws+errors+synchronously',+()+=>+{
++++return+true
++++throw+new+Error('it+works')
++})

++it('throws+errors+ansyncronously',+done+=>+{
++++setTimeout(()+=>+{
++++++return+done()
++++++done(new+Error('it+works'))
++++},+4)
++})

++it('uses+promises',+()+=>+{
++++var+testPromise+=+new+Promise((resolve,+reject)+=>+{
++++++setTimeout(()+=>+{
++++++++resolve('Hello')
++++++},+4)
++++})

++++testPromise.then(result+=>+{
++++++expect(result).to.equal('Hello')
++++},+reason+=>+{
++++++throw+new+Error(reason)
++++})
++})

++it('uses+es7+async/await',+async+(done)+=>+{
++++const+testPromise+=+new+Promise((resolve,+reject)+=>+{
++++++setTimeout(()+=>+{
++++++++resolve('Hello')
++++++},+4)
++++})

++++try+{
++++++const+result+=+await+testPromise
++++++expect(result).to.equal('Hello')
++++++done()
++++}+catch(err)+{
++++++done(err)
++++}
++})

++/*
++*++Higher-order+function+for+use+with+async/await+(last+test)
++*/
++const+mochaAsync+=+fn+=>+{
++++return+async+(done)+=>+{
++++++try+{
++++++++await+fn()
++++++++done()
++++++}+catch+(err)+{
++++++++done(err)
++++++}
++++}
++}

++it('uses+a+higher+order+function+wrap+around+async',+mochaAsync(async+()+=>+{
++++const+testPromise+=+new+Promise((resolve,+reject)+=>+{
++++++setTimeout(()+=>+{
++++++++resolve('Hello')
++++++},+4)
++++})

++++expect(await+testPromise).to.equal('Hello')
++}))
})|code-block|syntax|javascript|318511|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here are my passing tests for ES6/ES2015 promises and ES7/ES2016 async/await. Hope this provides a nice updated answer for anyone researching this topic:

<pre><code>import { expect } from 'chai'

describe('Mocha', () =&gt; {
 it('works synchronously', () =&gt; {
 expect(true).to.equal(true)
 })

 it('works ansyncronously', done =&gt; {
 setTimeout(() =&gt; {
 expect(true).to.equal(true)
 done()
 }, 4)
 })

 it('throws errors synchronously', () =&gt; {
 return true
 throw new Error('it works')
 })

 it('throws errors ansyncronously', done =&gt; {
 setTimeout(() =&gt; {
 return done()
 done(new Error('it works'))
 }, 4)
 })

 it('uses promises', () =&gt; {
 var testPromise = new Promise((resolve, reject) =&gt; {
 setTimeout(() =&gt; {
 resolve('Hello')
 }, 4)
 })

 testPromise.then(result =&gt; {
 expect(result).to.equal('Hello')
 }, reason =&gt; {
 throw new Error(reason)
 })
 })

 it('uses es7 async/await', async (done) =&gt; {
 const testPromise = new Promise((resolve, reject) =&gt; {
 setTimeout(() =&gt; {
 resolve('Hello')
 }, 4)
 })

 try {
 const result = await testPromise
 expect(result).to.equal('Hello')
 done()
 } catch(err) {
 done(err)
 }
 })

 /*
 * Higher-order function for use with async/await (last test)
 */
 const mochaAsync = fn =&gt; {
 return async (done) =&gt; {
 try {
 await fn()
 done()
 } catch (err) {
 done(err)
 }
 }
 }

 it('uses a higher order function wrap around async', mochaAsync(async () =&gt; {
 const testPromise = new Promise((resolve, reject) =&gt; {
 setTimeout(() =&gt; {
 resolve('Hello')
 }, 4)
 })

 expect(await testPromise).to.equal('Hello')
 }))
})
</code></pre>

blocks|key|535506|text|我解决了这个问题，将try/catch提取到一个函数中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|535507|function+asyncExpect(test,+done){
++++try{
++++++++test();
++++++++done();
++++}+catch(error){
++++++++done(error);
++++}
}|code-block|syntax|javascript|535508|然后在it()中，我调用：|535509|it('shall+update+a+host',+function+(done)+{
++++++++++++testee.insertHost({_id:+'host_id'})
++++++++++++++++.then(response+=>+{
++++++++++++++++++++asyncExpect(()+=>+{
++++++++++++++++++++++++expect(response).to.have.property('ok',+1);
++++++++++++++++++++++++expect(response).to.have.property('nModified',+1);
++++++++++++++++++++},+done);
++++++++++++++++});

++++++++});|535510|它也是可调试的。|535511|entityMap^0|A|9|0|0|3|4|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|10|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|R|$]]

I solved it extracting <code>try/catch</code> to a function.

<pre><code>function asyncExpect(test, done){
 try{
 test();
 done();
 } catch(error){
 done(error);
 }
}
</code></pre>

Then in <code>it()</code> I call:

<pre><code>it('shall update a host', function (done) {
 testee.insertHost({_id: 'host_id'})
 .then(response =&gt; {
 asyncExpect(() =&gt; {
 expect(response).to.have.property('ok', 1);
 expect(response).to.have.property('nModified', 1);
 }, done);
 });

 });
</code></pre>

It's also debugable.

blocks|key|535572|text|基于@richardforrester+http://staxmanade.com/2015/11/testing-asyncronous-code-with-mochajs-and-es7-async-await/提供的这个链接，如果省略done参数，describe可以使用返回的Promise。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|535573|唯一的缺点是必须有一个Promise，而不是任何异步函数(你可以用Promise包装它)。但在这种情况下，可以极大地减少代码。|535574|它考虑了初始funcThatReturnsAPromise函数或预期中的失败：|535575|it('should+test+Promises',+function+()+{+//+<=+done+removed
++++return+testee.funcThatReturnsAPromise({'name':+'value'})+//+<=+return+added
++++++++.then(response+=>+expect(response).to.have.property('ok',+1));
});|code-block|syntax|javascript|535576|entityMap|0|LINK|mutability|MUTABLE|url|http://staxmanade.com/2015/11/testing-asyncronous-code-with-mochajs-and-es7-async-await/^0|K|2G|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|6|7|Y|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|Z|8|@]|9|@]|C|$]]|$1|H|3|I|5|J|7|10|8|@]|9|@]|C|$K|L]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Based on this link provided by @richardforrester <a href="http://staxmanade.com/2015/11/testing-asyncronous-code-with-mochajs-and-es7-async-await/" rel="nofollow">http://staxmanade.com/2015/11/testing-asyncronous-code-with-mochajs-and-es7-async-await/</a>, describe can use a returned Promise if you omit the done parameter. 

Only downside there has to be a Promise there, not any async function (you can wrap it with a Promise, thou). But in this case, code can be extremely reduced.

It takes into account failings from either in the initial funcThatReturnsAPromise function or the expectations:

<pre><code>it('should test Promises', function () { // &lt;= done removed
 return testee.funcThatReturnsAPromise({'name': 'value'}) // &lt;= return added
 .then(response =&gt; expect(response).to.have.property('ok', 1));
});
</code></pre>

blocks|key|535604|text|您也可以使用域模块。例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|535605|var+domain+=+require('domain').create();

domain.run(function()
{
++++//+place+you+code+here
});

domain.on('error',function(error){
++++//+do+something+with+error+or+simply+print+it
});|code-block|syntax|javascript|535606|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can also use domain module. For example:

<pre><code>var domain = require('domain').create();

domain.run(function()
{
 // place you code here
});

domain.on('error',function(error){
 // do something with error or simply print it
});
</code></pre>

blocks|key|535644|text|试试chaiAsPromised吧！除了可以很好地命名之外，您还可以使用以下语句：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|535645|expect(asyncToResultingValue()).to.eventually.equal(true)|offset|length|style|CODE|535646|Can+confirm，在Mocha+%2B+Chai上工作得很好。|535647|https://github.com/domenic/chai-as-promised|535648|entityMap|0|LINK|mutability|MUTABLE|url|https://i.stack.imgur.com/ff6Ce.gif|1^0|0|0|1L|0|0|B|0|0|0|17|1|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@$D|Z|E|10|1|11]]|A|$]]|$1|J|3|K|5|6|7|12|8|@]|9|@$D|13|E|14|1|15]]|A|$]]|$1|L|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S]]|T|$5|O|P|Q|A|$R|K]]]]

Try chaiAsPromised! Aside from being excellently named, you can use statements like:

<code>expect(asyncToResultingValue()).to.eventually.equal(true)</code>

<a href="https://i.stack.imgur.com/ff6Ce.gif" rel="nofollow noreferrer">Can confirm</a>, works very well for Mocha + Chai.

<a href="https://github.com/domenic/chai-as-promised" rel="nofollow noreferrer">https://github.com/domenic/chai-as-promised</a>

blocks|key|318711|text|与Jean+Vincent's+answer非常相关并受其启发，我们使用了一个类似于他的check函数的助手函数，但我们将其称为eventually+(这有助于它与chai-as-promised的命名约定相匹配)。它返回一个函数，该函数接受任意数量的参数并将它们传递给原始回调。这有助于消除测试中的额外嵌套函数块，并允许您处理任何类型的异步回调。下面是用ES2015编写的代码：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|318712|function+eventually(done,+fn)+{
++return+(...args)+=>+{
++++try+{
++++++fn(...args);
++++++done();
++++}+catch+(err)+{
++++++done(err);
++++}
++};
};|code-block|syntax|javascript|318713|示例用法：|318714|describe("my+async+test",+function()+{
++it("should+fail",+function(done)+{
++++setTimeout(eventually(done,+(param1,+param2)+=>+{
++++++assert.equal(param1,+"foo");+++//+this+should+pass
++++++assert.equal(param2,+"bogus");+//+this+should+fail
++++}),+100,+"foo",+"bar");
++});
});|318715|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/15208067/8985^0|18|5|1S|A|1|L|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|15|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

Very much related to and inspired by <a href="https://stackoverflow.com/a/15208067/8985">Jean Vincent's answer</a>, we employ a helper function similar to his <code>check</code> function, but we call it <code>eventually</code> instead (this helps it match up with the naming conventions of chai-as-promised). It returns a function that takes any number of arguments and passes them to the original callback. This helps eliminate an extra nested function block in your tests and allows you to handle any type of async callback. Here it is written in ES2015:

<pre><code>function eventually(done, fn) {
 return (...args) =&gt; {
 try {
 fn(...args);
 done();
 } catch (err) {
 done(err);
 }
 };
};
</code></pre>

Example Usage:

<pre><code>describe("my async test", function() {
 it("should fail", function(done) {
 setTimeout(eventually(done, (param1, param2) =&gt; {
 assert.equal(param1, "foo"); // this should pass
 assert.equal(param2, "bogus"); // this should fail
 }), 100, "foo", "bar");
 });
});
</code></pre>

blocks|key|318767|text|我知道有很多重复的答案和建议的包来解决这个问题，但是我还没有看到上面的简单解决方案为这两个用例提供了一个简洁的模式。我发布这篇文章是为了给其他想要复制-意大利面的人提供一个综合的答案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|318768|事件回调|318769|function+expectEventCallback(done,+fn)+{
++return+function()+{
++++try+{+fn(...arguments);+}
++++catch(error)+{+return+done(error);+}
++++done();
++};
}|code-block|syntax|javascript|318770|节点样式回调|318771|function+expectNodeCallback(done,+fn)+{
++return+function(err,+...args)+{
++++if+(err)+{+return+done(err);+}
++++try+{+fn(...args);+}
++++catch(error)+{+return+done(error);+}
++++done();
++};
}|318772|示例用法|318773|it('handles+event+callbacks',+function(done)+{
++something.on('event',+expectEventCallback(done,+(payload)+=>+{
++++expect(payload).to.have.propertry('foo');
++}));
});

it('handles+node+callbacks',+function(done)+{
++doSomething(expectNodeCallback(done,+(payload)+=>+{
++++expect(payload).to.have.propertry('foo');
++}));
});|318774|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I know there are many repeat answers and suggested packages to solve this however I haven't seen the simple solutions above offer a concise pattern for the two use cases. I am posting this as a consolidated answer for other who wish to copy-pasta:

<h2>event callbacks</h2>

<pre><code>function expectEventCallback(done, fn) {
 return function() {
 try { fn(...arguments); }
 catch(error) { return done(error); }
 done();
 };
}
</code></pre>

<h2>node style callbacks</h2>

<pre><code>function expectNodeCallback(done, fn) {
 return function(err, ...args) {
 if (err) { return done(err); }
 try { fn(...args); }
 catch(error) { return done(error); }
 done();
 };
}
</code></pre>

<h2>example usage</h2>

<pre><code>it('handles event callbacks', function(done) {
 something.on('event', expectEventCallback(done, (payload) =&gt; {
 expect(payload).to.have.propertry('foo');
 }));
});

it('handles node callbacks', function(done) {
 doSomething(expectNodeCallback(done, (payload) =&gt; {
 expect(payload).to.have.propertry('foo');
 }));
});
</code></pre>

blocks|key|318820|text|测试和异步过程中的计时器听起来很粗糙。有一种基于promise的方法可以做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|318821|const+sendFormResp+=+async+(obj)+=>+{
++++const+result+=+await+web.chat.postMessage({
++++++++text:+'Hello+world!',
++++});
+++return+result
}|code-block|syntax|javascript|318822|此异步函数使用Web客户端(在本例中为Slacks+)。SDK负责API调用的异步特性，并返回有效负载。然后，我们可以通过对异步promise中返回的对象运行expect来测试chai中的有效负载。|offset|length|style|CODE|318823|describe("Slack+Logic+For+Working+Demo+Environment",+function+(done)+{
++++it("Should+return+an+object",+()+=>+{
++++++++return+sdkLogic.sendFormResp(testModels.workingModel).then(res+=>+{
++++++++++++expect(res).to.be.a("Object");
++++++++})
++++})
});|318824|entityMap^0|0|0|27|6|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Timers during tests and async sounds pretty rough. There is a way to do this with a promise based approach.

<pre><code>const sendFormResp = async (obj) =&gt; {
 const result = await web.chat.postMessage({
 text: 'Hello world!',
 });
 return result
}
</code></pre>

This async function uses a Web client (in this case it is Slacks SDK). The SDK takes care of the asynchronous nature of the API call and returns a payload. We can then test the payload within chai by running <code>expect</code> against the object returned in the async promise.

<pre><code>describe("Slack Logic For Working Demo Environment", function (done) {
 it("Should return an object", () =&gt; {
 return sdkLogic.sendFormResp(testModels.workingModel).then(res =&gt; {
 expect(res).to.be.a("Object");
 })
 })
});
</code></pre>

blocks|key|318848|text|一种更简单的方法是使用wait-for-expect库。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|318849|const+waitForExpect+=+require("wait-for-expect")

test("it+waits+for+the+number+to+change",+async+()+=>+{
++let+numberToChange+=+10;

++setTimeout(()+=>+{
++++numberToChange+=+100;
++},+randomTimeout);

++await+waitForExpect(()+=>+{
++++expect(numberToChange).toEqual(100);
++});
});|code-block|syntax|javascript|318850|entityMap|0|LINK|mutability|MUTABLE|url|https://www.npmjs.com/package/wait-for-expect^0|B|F|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

A simpler approach would be using <a href="https://www.npmjs.com/package/wait-for-expect" rel="nofollow noreferrer">wait-for-expect</a> library.
<pre class="lang-js prettyprint-override"><code>const waitForExpect = require(&quot;wait-for-expect&quot;)

test(&quot;it waits for the number to change&quot;, async () =&gt; {
 let numberToChange = 10;

 setTimeout(() =&gt; {
 numberToChange = 100;
 }, randomTimeout);

 await waitForExpect(() =&gt; {
 expect(numberToChange).toEqual(100);
 });
});
</code></pre>

I'm running some asynchronous tests in Mocha using the Browser Runner and I'm trying to use Chai's expect style assertions:

<pre><code>window.expect = chai.expect;
describe('my test', function() {
 it('should do something', function (done) {
 setTimeout(function () {
 expect(true).to.equal(false);
 }, 100);
 }
}
</code></pre>

This doesn't give me the normal failed assertion message, instead I get:

<pre><code>Error: the string "Uncaught AssertionError: expected true to equal false" was thrown, throw an Error :)
 at Runner.fail (http://localhost:8000/tests/integration/mocha/vendor/mocha.js:3475:11)
 at Runner.uncaught (http://localhost:8000/tests/integration/mocha/vendor/mocha.js:3748:8)
 at uncaught (http://localhost:8000/tests/integration/mocha/vendor/mocha.js:3778:10)
</code></pre>

So it's obviously catching the error, it's just not displaying it correctly. Any ideas how to do this? I guess I could just call "done" with an error object but then I lose all the elegance of something like Chai and it becomes very clunky...

Is there a way to get Chai working with asynchronous Mocha tests?

我正在使用Browser Runner在Mocha中运行一些异步测试，并尝试使用Chai的expect风格断言：window.expect = chai.expect;describe('my test', function() {  it('should do something', function (done) ...

问有没有办法让Chai使用异步Mocha测试？
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