Add repr() calls to "invalid value" exception message in StrConverter.to_bool

[ptmcg]

After upgrading to 4.0, we are getting the following exceptions in our build pipeline:

File "/tmp/tmpw_2jv6x3/python-test-env/lib/python3.9/site-packages/tox/config/cli/parser.py", line 293, in add_color_flags
    if converter.to_bool(os.environ.get("NO_COLOR", "")):
File "/tmp/tmpw_2jv6x3/python-test-env/lib/python3.9/site-packages/tox/config/loader/str_convert.py", line 90, in to_bool
    raise TypeError(f"value {value} cannot be transformed to bool, valid: {', '.join(StrConvert.VALID_BOOL)}")
TypeError: value  cannot be transformed to bool, valid: , 0, 1, false, no, off, on, true, yes

We cannot reproduce the issue locally, else we would have more debugging tools and options.

This PR adds !r to display the repr() of the bad value, as well as repr()'s the values in VALID_BOOL, to help diagnose issues when running locally is not an option.

Thanks for contribution

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[gaborbernat]

Also needs a test. My guess is you're passing an empty string for boolean.

[ptmcg]

Thanks for the quick review, by the way!

That was our thought as well (passing in an empty string), but the logic in the code should be able to handle an empty string, as that appears to be one of the values in VALID_BOOL.

I looked for other tests, but did not see any for this method.

[gaborbernat]

I looked for other tests, but did not see any for this method.

https://github.com/tox-dev/tox/blob/main/tests/config/test_sets.py#L92

[ptmcg]

Ah, I was looking for something specifically testing to_bool(). Found the appropriate test, updated the expected error message.

[ptmcg]

Reverted repr() on VALID_BOOL list items, and updated existing test to reflect changed message.