Change tst/testall.g to quit GAP with exit status indicating outcome

[fingolfin]

This is what we want for e.g. tests in the package distro

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.22%. Comparing base (77840f6) to head (d5915b1).
Report is 14 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #31      +/-   ##
==========================================
- Coverage   93.71%   93.22%   -0.50%     
==========================================
  Files           3        3              
  Lines         175      177       +2     
==========================================
+ Hits          164      165       +1     
- Misses         11       12       +1     

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[fingolfin]

This causes CI to pass but only because we now quit GAP with an exit code in tst/testall.g. But the second GAP process that gets launched from the primary GAP still runs into an error; it just doesn't get reported back to the top level GAP ...

I don't like papering over the issue, so I'll not merge this for now

[fingolfin]

Ah, the failures are not new: #22

[fingolfin]

The test file is not very useful right now either (other than showing that the test setup is broken). @RussWoodroofe added in PR #16 (thanks you!), but right now all it does is run all tests in .tst files -- of which there are none.

But more worryingly, this test setup relies on the GAP function InputOutputLocalProcess. As described here this function is quite limited and among other problems does not allow querying the exit status of the subprocess. So there is fundamentally no way to do that as a check.

Right now the only way for a complete solution I can think of is to replace this test setup by a different one that is not driven by GAP, but rather by python/perl/a shell script/whatever.

That said, perhaps we can come up with a way to at least patch this enough to be useful?