fix: exit if the coverage threshold is not met

[vladjerca]

I've investigated a bit what the differences were between 4.1.1 and 5.x.y, I noticed that the package was previously doing sync operations.

Since 5.0.0 the coverage calculations are done via the istanbul-lib-coverage package to process the results.

The issue here is that the processing is now async and mutation of the results.exitCode property is now part of a microTask.

The only solution I could find was to aggregate all of the threshold checks and actually exit once all of the checks are performed.

fix #376

[erikbarke]

Hey @vladjerca, great work!!

[vladjerca]

@erikbarke Glad to help! 🥳

[vladjerca]

@erikbarke Do you still need me to do anything on this bit?

[erikbarke]

Why do we need the variable isBelowCoverageThreshold here, it's always false? Wouldn't we achieve the same result by just checking isCoverageCheckFailed and exit if it's true?

[erikbarke]

@vladjerca

[vladjerca]

@erikbarke isCoverageCheckFailed is the local browser instance check, where as isBelowCoverageThreshold is the aggregate for entire run.

Now to expand a bit on why I aggregate rather than do a hard exit: I do this in order to allow all of the coverage reports to be logged before the reporter triggers a process exit 🤓

LE: also isBelowCoverageThreshold isn't always false it starts off as false.

[erikbarke]

Ok, got it!

[erikbarke]

@vladjerca, I totally forgot to submit the review, it's been sitting there for days unsubmitted 😞