TypeError exception message does not display erroneous value

[ptmcg]

Issue

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.

The exception message is not showing us what the incorrect value is. While it appears that it might be the empty string, an empty string is included in the VALID_BOOL list, and so should not raise the TypeError. So we suspect some other value, but since it is non-printing, we cannot diagnose.

I am submitting a PR to add !r and repr() calls in the to_bool method to make the exception message clearer, so that we can better diagnose the underlying issue.

[gaborbernat]

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

Can't mark this a bug until we have a reproducer.

[ptmcg]

Fair enough. I guess this is actually more like a feature request. We would like this exception message to be enhanced so that it shows the actual value that we are failing on.

[gaborbernat]

Done via https://github.com/tox-dev/tox/pull/2666/files and released.

[ptmcg]

Thanks so much for your expeditious handling of this!

We can now see in our log a more helpful message:

TypeError: value '\x1b[0m' cannot be transformed to bool, ...

I suspect a command with colorized output (perhaps colorizing was a recent addition) was run using subprocess.run() or similar, the output captured and then naively parsed to extract 1, 0, Y, N, etc. but got the terminal escape sequence instead.

Now we have a solid lead to follow!