Colourise diffs in test.File

[FollowTheProcess]

Summary

Does rudimentary colourisation in the diff produced by test.File to make it easier to parse, this does not respect $NO_COLOR or $FORCE_COLOR

Now looks like this:

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 13 lines in your changes missing coverage. Please review.

Project coverage is 86.77%. Comparing base (4464136) to head (5b27546).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
test.go	0.00%	12 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #43      +/-   ##
==========================================
- Coverage   90.90%   86.77%   -4.14%     
==========================================
  Files           1        1              
  Lines         231      242      +11     
==========================================
  Hits          210      210              
- Misses         11       22      +11     
  Partials       10       10              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.