tests: add test cases for wide character path conversions

[striezel]

Description

Add test cases for the fixes made in #746 to avoid future regressions.

(This is the first time I created a test case for GIL, so it might not build and pass on first try.)

References

• PR fix wrong buffer size in path string conversion functions #746
• Test string is taken from heap-buffer-overflow when using io-related functions #733, the issue where the error was reported.

Tasklist

• Add test case(s)
• Ensure all CI builds pass
• Review and approve

[striezel]

Tests passed on first try? 😮

[mloskot]

Thank you!

[striezel]

Now that I know how to use Boost's lightweight_test I hope to write more tests in the future. :) Especially when bugs get fixed, there should be some regression tests for the fix to avoid reintroducing a bug by accident.

[mloskot]

there should be some regression tests for the fix to avoid reintroducing a bug by accident

Indeed.

We encourage PR authors to always cover features and fixes with tests, from https://github.com/boostorg/gil/blob/develop/CONTRIBUTING.md#pull-requests

DO ensure any new features or changes to existing behaviours are covered with test cases.

IMO, tests are also a very useful source of 'expected behaviour documentation', especially when the prose documentation is lacking.