When a `fail` occurs before a done() call, the error message is wrong

Given the following code:

 Promise.all(typePromises).then(results => {
     console.log(results)
     expect(results).not.to.contain(false);
     done();
 });

I would expect chai to give me an error saying it expected the array not to contain false, if it does contain false.

However, when this is the case I instead get the following error after 2 seconds:
Error: timeout of 2000ms exceeded. Ensure the done() callback is being called in this test.

Clearly my code contains a done() call, and it is called correctly when my test passes. However, when the .not.to.contain detects a failure it is not called.

[keithamus]

Thanks for the issue @DannyBrown. Thanks for helping out there @lucasfcosta

The reason this is not doing what you want is because Chai throws errors when an assertion fails. So your code never reaches done(), and the Promise gets turned into an error state - but because you’re doing nothing else with the Promise, it never goes anywhere, and subsequently your test is timing out.

You probably want to do the following instead:

 Promise.all(typePromises).then(results => {
     console.log(results)
     expect(results).not.to.contain(false);
 }).then(() => done(), error => done(error));

Which can be shortened to

 Promise.all(typePromises).then(results => {
     console.log(results)
     expect(results).not.to.contain(false);
 }).then(done, done);

Alternatively, if you’re using Mocha, you can actually return the Promise in your it call, and Mocha will handle it all for you:

it('retrieves all results', () => {
 return Promise.all(typePromises).then(results => {
     console.log(results)
     expect(results).not.to.contain(false);
 });
});

I’ll close this, because I’m pretty certain the above examples will fix your problems. If they don’t, or you have any more questions, feel free to comment and we can continue discussing this. Have a great day 😄 👍

[keithamus]

@michaelgallaghertw I would avoid using finally to call done. This would make tests pass, even if the expect() throws an error, as finally is given no arguments. .then(done, done) correctly passes the error back to mocha.