test(cmd-api-server): fix flaky runtime-plugin-imports-test

[Leeyoungone]

This is a flaky test case that can't be reliably reproduce. I've ran the test individually 40 times and all 40 times it has passed successfully.

This error, however, seems to pop up only when the yarn jest command is run (when I ran the test individually).

Based on the linked "hint" from the issue, it seems like using jest.useFakeTimers() a good solution. However, using the jest.useFakeTimers() withasync/await was not recommended.

However, I found a different source that showed examples of how to use the jest.useFakeTimers(). Our original problem, however, is probably because the after the test environment is torn down, the second test file is trying to import files from the first environment, triggering the error (explained here). So I've come to the solution of installing another node package: node-cleanup and running that within the afterAll at the very end of the test.

My laptop can't take running the yarn jest script too much so I haven't seen it reproduce the error yet. (WOT ruhrow)

_______________________edit below _________________________

So it turns out that this flaky test due to libraries trying to third libraries trying to run after the test runs is a simple fix that was documented here where we just add the useRealTimer in the afterEach. Lol so sorry!!

Fixes #1667

[petermetz]

@Leeyoungone Great investigation I'm pretty sure you are on the right track. I read the documentation of node-cleanup and the way you are using it now seems to be a no-op to me because the purpose of the library is to provide hooks where the user (who is the person writing the Cactus code in this case) can do the "cleanup" logic themselves if they know that some allocated resource (TCP socket, file handle, database lock, etc.) is still being held onto. The point is, the node-cleanup library doesn't magically know what to clean up, it just gives you the opportunity to do so yourself (and right now what you technically do when you invoke the library's function is just saying that you want do the cleanup, but then you aren't).
So in that sense, I think this warrants a little more investigation, but you are definitely on the right track!

[Leeyoungone]

@petermetz Thank you so much for the advice! I've dug into it a little more and I think that adding the useRealTimers within the afterEach should fix this flaky issue (as mentioned here). My laptop with 8 GB of RAM isn't strong enough to withstand running all the jest tests to replicate this flaky issue. I might just have to Hail Mary this PR and hope this solves it.

[petermetz]

@Leeyoungone Hmm, yarn.lock is still in diff if you look here: https://github.com/hyperledger/cactus/pull/1903/files
Did you forget to push your changes maybe?

[petermetz]

@Leeyoungone LGTM, thank you!