test(inpath): improve Windows and unix test for inpath()

[JigyasuRajput]

Description

Fixes #2928

This PR improves test coverage for the inpath() function by ensuring it is properly tested on both Windows and Unix-based systems. The function previously had limited coverage, particularly on Windows, where it was not correctly detecting executables in PATH.

Changes Made

Improvements to inpath() in cve_bin_tool/util.py:

• Refactored Windows path handling to remove unnecessary nested operations, improving readability and efficiency.
• Ensured consistent logic for checking if a binary exists in the system's PATH.

New and Improved Test Cases in test/test_util.py:

1. test_inpath_windows

   • Mocks Windows PATH environment and verifies that inpath() correctly finds executables (python.exe).
   • Uses monkeypatching to simulate file presence and permissions in Windows directories.

2. test_inpath_non_windows

   • Mocks Unix/Linux PATH and verifies that inpath() correctly detects executables with proper permissions (os.access).

3. test_inpath_empty_path

   • Ensures inpath() returns False when the PATH environment variable is empty.

Impact

• Increases test coverage for inpath() on both Windows and Unix-based systems.
• Fixes potential issues in Windows detection by refining the logic for .exe handling.
• Enhances reliability by covering edge cases such as empty PATH and incorrect file permissions.

How to Verify

Run the test suite to confirm functionality:

pytest test/test_util.py --tb=short -v

[terriko]

quick heads up: this one's showing as having a conflict, which is why the tests can't be run.

[JigyasuRajput]

I've resolved the merge conflict. Thanks for pointing it out!

[terriko]

The tests aren't passing on windows, which looks very relevant to this:

 =========================== short test summary info ===========================
FAILED test/test_util.py::TestUtil::test_inpath_non_windows - AssertionError: assert False is True
 +  where False = inpath('python')
===== 1 failed, 2205 passed, 47 skipped, 7 warnings in 2223.54s (0:37:03) =====