Code size report:

   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:    +0 +0.000% PYBV10
     mimxrt:    +0 +0.000% TEENSY40
        rp2:    +0 +0.000% RPI_PICO_W
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS
  qemu rv32:    +0 +0.000% VIRT_RV32

There are of course different naming conventions that could be used for the "run a test subset" rules test/% and test//%. Here's the reasoning that led to the current forms:

• I started with test-a-% and test-d-% to mirror the commandline flags, but for sub directories to be accepted by the directory test pattern, the % had to follow a /, so it would have to be test/% test-d/% or similar. I went with the shortest test/%.
• similarly the regular expression based search would need to be of a similar form if patterns with an embedded / are important. Such patterns might occur, like if you want to test everything that matches the pattern basics/.*int for example. It turns out that with //% and /% patterns, make picks the correct (longest prefix?) one, at least in my testing. If one "/" introduces "here's what to test" (and has to for technical reasons of GNU make), the vi user in me finds "//" as "ditto, but it's a search" to be natural.

And would that pattern work with WindowsPaths \ as well ?

That's a good question! I don't have any Windows machines available to test.

Since most path like stuff is handled just fine by make even though Windows uses a different directory separator, I think the part where it gets the test selection into $* will be the same.

The run-tests script is careful to replace windows-style directory separators with forward slash ones before applying filters (see around line 884), so I think there's a good chance that make test//basics/.*int would work in a cross-platform way.

It would be great if someone can actually test on Windows and advise how to update the readme about any caveats that may exist. If someone does I'll update it.

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.38%. Comparing base (744270a) to head (0a119b8).
⚠️ Report is 17 commits behind head on master.

@@           Coverage Diff           @@
##           master   #17921   +/-   ##
=======================================
  Coverage   98.38%   98.38%           
=======================================
  Files         171      171           
  Lines       22295    22298    +3     
=======================================
+ Hits        21936    21939    +3     
  Misses        359      359           

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I found some time.

under MSYS2 + the same changes to the windows makefile - the test selection also works fine.
while make itself runs on plain powershell - the rest of the toolchain not.

So while it works, I don't think its worth the effort to add to the windows makefile.