Improve tests code more

[perillo]

Additional improvements to kcov test suite.

• [x] tests: validate testbase.configure arguments

  Ensure that all the paths in testbase.configure are not empty and normalized.

  Ensure that outbase is not the current working directory.

• [x] tests: convert simple % style string format to f-string

  Convert old formatting style to f-string style, using python3 -m libcst.tool codemod convert_percent_format_to_fstring.ConvertPercentFormatStringCommand

• [x] tests: remove unnecessary call to setUp method.

  It is not necessary because setUp is called automatically by TestCase.run.

• [x] tests: use skipTest instead of print and return

  Using skipTest is the preferred method for skipping tests. Now the test message is printed on the same line.

• [x] tests: override TestCase.tearDown in testbase.py

  Use os.makedirs to create the kcov directory in setUp and shutil.rmtree to remove it in tearDown.

  Don't use the shell, since errors are not propagated.

• [x] Ensure the "kcov-kcov" directory uses a fixed path

  In ci.yml, codecov assumes that the output directory is "/tmp/kcov-kcov".

  Don't assume that outbase is always "/tmp", and instead use the "/tmp/kcov-kcov" path.

NOTES

• I used tools to automate refactoring, like LibCST and sed.

• LibCTS codemod for converting old format to f-string unfortunately added parenthesis in some non simple statement. Only later I found that there was another tool flynt but I have not used it to see if there are differences in formatting.

• When removing calls to setUp method, I also inadvertently removed calls to setUp method inside the doTest method. This is fine, since doTest is always called from the runTest method so setUp is always called.

TODO

I noted that doShell is used only two times; other code using the shell use system.

Additionally, both doShell and system does not propagate errors, so I plan to make this more robust in a separate PR. I also plan to group shell commands, instead of spawning a subprocess for every command line.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 65.68%. Comparing base (5ae73ae) to head (505cb60).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #431 +/- ## ======================================= Coverage 65.68% 65.68% ======================================= Files 58 58 Lines 4514 4514 Branches 4171 4171 ======================================= Hits 2965 2965 Misses 1549 1549 ```

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[SimonKagstrom]

Beautiful! Thanks a lot for taking on the testsuite!

[perillo]

Thanks to you for the review.