Promises still in the event Loop
I'm having a problem with unit tests in mocha, while testing a function that uses co. Since Mocha 4 tests don't exit automatically anymore when things are still 'hanging' in the event loop. (server connections, unresolved promises, etc...)
Below is a simple test file, notice the after hook, which dumps things that are still in the event loop: The test doesn't exit while it should! When I take the Error out of the generator function, it works as expected, but in my real use case that's not what I want.
Under the code you can see 3 Promises that are still pending after running the tesr (logged to console)
'use strict';
const co = require('co');
/** sample class for testing **/
class myTest {
static doStuff(name){
return co(function* coStart() {
if (name !== 'john') {
throw new Error('invalid data, wrong name');
}
//further more I do some async stuff
let ret = yield Promise.resolve('good');
return ret;
});
}
}
/** mocha test **/
describe('test', function () {
const assert = require('assert');
after(function () {
global.asyncDump();
});
describe('doStuff', function () {
it('should reject when using a name thats not john', function (done) {
myTest.doStuff('bert')
.then(() => done('it should fail'))
.catch(function(err){
assert.equal(err.message, 'invalid data, wrong name');
done();
});
});
});
});logs:
STUFF STILL IN THE EVENT LOOP:
Type: SIGNALWRAP
Error
at AsyncHook.init (async-dump.js:12:62)
at Signal.emitInitNative (async_hooks.js:472:43)
at process.<anonymous> (internal/process.js:204:20)
at startup (bootstrap_node.js:187:16)
at bootstrap_node.js:608:3
Type: PROMISE
Error
at AsyncHook.init (async-dump.js:12:62)
at PromiseWrap.emitInitNative (async_hooks.js:472:43)
at new Promise (<anonymous>)
at co (node_modules/co/index.js:50:10)
at Function.doStuff (server/tests/unit/test.js:7:16)
at Context.<anonymous> (server/tests/unit/test.js:27:20)
Type: PROMISE
Error
at AsyncHook.init (async-dump.js:12:62)
at PromiseWrap.emitInitNative (async_hooks.js:472:43)
at Promise.then (<anonymous>)
at Context.<anonymous> (server/tests/unit/test.js:28:18)
Type: PROMISE
Error
at AsyncHook.init (async-dump.js:12:62)
at PromiseWrap.emitInitNative (async_hooks.js:472:43)
at Promise.catch (<anonymous>)
at Context.<anonymous> (server/tests/unit/test.js:29:23)
Type: Immediate
Error
at AsyncHook.init (async-dump.js:12:62)
at emitInitNative (async_hooks.js:472:43)
at emitInitScript (async_hooks.js:388:3)Im running the test with this command:
./node_modules/mocha/bin/_mocha --require async-dump server/tests/unit/test.js -R spec
The async-dump-script I require is from this gist: https://gist.github.com/subfuzion/54a9413d02c6d9ba223076bebd49e38f
Is this considered a bug (that can cause memory issues)?
I've tried with Promise.reject instead of throwing errors, and also yield Promise.reject, but that doesn't help either.
I'm aware that mocha has an --exit flag to exit anyway, but it's considered bad practice, I want to make sure nothing keeps hanging.
My node version is v8.9.1
Thx in advance
Source: tj/co