[Server] Jest open handles

[devYaoYH]

yarn test - Success
yarn test --detectOpenHandles - Last test fails
Need to investigate further

[devYaoYH]

Side effect of detected open handles also preventing jest from exiting after tests are complete

• Delays completion of server testing script by ~1min

[devYaoYH]

Side-effect of #105, resolving that issue would resolve this one as well.

[redhoteggplant]

Just adding a note that open handles are separate and seem to be an issue in supertest, and current workarounds are just using setTimeout() or --forceExit

[redhoteggplant]

(Just adding more information in case we come back to this issue)

Running jest test gives the following warning:

Jest did not exit one second after the test run has completed.

This usually means that there are asynchronous operations that weren't stopped in your tests. Consider running Jest with `--detectOpenHandles` to troubleshoot this issue.

Running jest --detectOpenHandles as suggested detects open handles from app.listen() or request(app).get(), with an example output below:

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  TCPSERVERWRAP

      38 | app.use(compression());
      39 | 
    > 40 | server = app.listen(PORT, function () {
         |              ^
      41 |   console.log(config.ENV);
      42 | });
      43 | 

Attempts:

1. server.close() at the end of all tests
2. server.close() in afterAll()
3. server.close(done)
4. Remove app.listen() and server.close() in test env, similar to here
5. setting up an agent that uses the allocated port instead of a random port, or using end() to force supertest to close the automatic bound connection, as suggested in the supertest issue #520
6. Add Promise.all(firebase.apps().map(app => app.delete())) to clean up Firebase apps after tests, as the docs note that that initialized apps with active listeners prevent JavaScript from exiting
7. Hacky ways: run jest with --forceExit, or setTimeout() after all tests