Forbid node-style done callback in mocha it tests #8966
Description
Imagine code like this:
it('test stuff', done => {
unit.doSomething();
setTimeout(() => {
expect(somethingDoneAsync).equal('value');
done();
}, 0);
});But, there's a trap! If that expectation does not pass, we never hit the done callback and the assertion error will be swallowed!
The only appropriate way to use done callbacks in tests are:
// Promises. This is what we should be doing.
it('test stuff', () => {
unit.doSomething();
return new Promise(resolve => {
setTimeout(resolve, 0));
}).then(() => {
expect(somethingDoneAsync).equal('value');
});
});// Node style. But why would you do this?
setTimeout(() => {
let error = null;
try {
expect(somethingDoneAsync).equal('value');
} catch (e) {
error = e;
}
done(error);
}, 0);