fix: async abstract.js

[seriousme]

This PR:

• introduces t.plan in all tests to ensure that all asserts are evaluated
• restructures the tests so that in case of failure you directly get access to the specific test instead of the same function that executes all tests
• changes nearly all callbacks to async/await to ensure that all errors are caught.
• has been tested with aedes-persistence-redis. These tests d̀id complete without requiring process.exit(0) but you need to disable waitForReady:true for these tests as the ready event seems to come too early.
• adds a new test to test suite that tests the working of the ẁaitForReady:true

Hope this helps,
Hans

[seriousme]

After testing abstract.js with aedes-persistence-level I got a warning:
[DEP0174] DeprecationWarning: Calling promisify on a function that returns a Promise is likely a mistake.
So I decided to remove promisify in doCleanup().

[robertsLando]

@seriousme well done with this refactor! Looks good overall, just wondering why coveralls detects a decrease of coverage

[seriousme]

@seriousme well done with this refactor! Looks good overall, just wondering why coveralls detects a decrease of coverage

@robertsLando Just checked the coverage report: it turns out the async test missed the waitForReady:true flag :-(
This left waitForEvent() uncalled, and therefore coverage dropped. All other coverage misses are untriggered errors in promises.

[robertsLando]

it turns out the async test missed the waitForReady:true flag :-(
This left waitForEvent() uncalled, and therefore coverage dropped

Could you fix that? Then I will release a patch