test: print test errors only when finished

[Llorx]

Fixes#56316

TODO: Add/modify tests (will do later, just pushing this to validate that this is the way to go for changes like this).

I just added a flag to make a conditional output. Is this the usual way to go with NodeJS @pmarchini ?

About the feature, I'm not sure if everyone will like it like this. Maybe add an opt-in flag to format the errors before the report has finished? (like it was before, but now is opt-in). Or maybe don't add a flag now, and maybe add the opt-in flag later if we receive complaints?

[nodejs-github-bot]

Review requested:

• @nodejs/test_runner

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.54%. Comparing base (be9dc2d) to head (ce5c8c0).
Report is 532 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/test_runner/reporter/utils.js	87.50%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## main #56351 +/- ##
=======================================
Coverage 88.54% 88.54% =======================================
Files 657 657 Lines 190350 190353 +3 Branches 36545 36554 +9 =======================================
+ Hits 168536 168549 +13 - Misses 14992 14999 +7 + Partials 6822 6805 -17 

Files with missing lines	Coverage Δ
lib/internal/test_runner/reporter/spec.js	96.19% <100.00%> (ø)
lib/internal/test_runner/reporter/utils.js	94.68% <87.50%> (-2.03%)	⬇️

... and 36 files with indirect coverage changes

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[cjihrig]

About the feature, I'm not sure if everyone will like it like this. Maybe add an opt-in flag to format the errors before the report has finished? (like it was before, but now is opt-in). Or maybe don't add a flag now, and maybe add the opt-in flag later if we receive complaints?

It's possible for anyone to write their own reporter to make it look exactly how they want. There are already a number of reporters available on npm, and one potentially in the works for node core. We also don't make semver guarantees about exact reporter formatting.

Can you update the tests so that this doesn't get stalled out.

[cjihrig]

ping @Llorx. Are you still working on this? If not, can we close this PR out? I'd like to see this issue get resolved.