Improve test coverprofile

[turbolent]

Description

The current default for the test --coverprofile flag is coverage.json, i.e. creating a non-standard JSON-based coverage file. (@m-Peter or does the JSON format follow a particular "standard"?).

Switch the default to the LCOV file format, which is widely supported by tools, in particular the common file name lcov.info. Note that LCOV files are info files. To make this work, also add support for .info extension.

For example, this allows using Visual Studio Code extension Coverage Gutters:

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For contributor use:

• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 28.47%. Comparing base (606ca7a) to head (977fd87).

Files with missing lines	Patch %	Lines
internal/test/test.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1801   +/-   ##
=======================================
  Coverage   28.47%   28.47%           
=======================================
  Files          95       95           
  Lines        6490     6490           
=======================================
  Hits         1848     1848           
  Misses       4462     4462           
  Partials      180      180           

Flag	Coverage Δ
unittests	28.47% <0.00%> (ø)

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[m-Peter]

Description

The current default for the test --coverprofile flag is coverage.json, i.e. creating a non-standard JSON-based coverage file. (@m-Peter or does the JSON format follow a particular "standard"?).

Switch the default to the LCOV file format, which is widely supported by tools, in particular the common file name lcov.info. Note that LCOV files are info files. To make this work, also add support for .info extension.

For example, this allows using Visual Studio Code extension Coverage Gutters:

@turbolent Good catch 👏
The JSON format does not really follow any established standard out there, it was just the first type of format which was added.