chore: create our test case for pre_filter.py

[h1alexbel]

PR-Codex overview

This PR introduces improvements to the TestPreFilter class in test_pre_filter.py. It enhances directory handling and adds tests for directory creation and output file generation.

Detailed summary

• Introduced DIR constant for directory name
• Updated directory handling in setUp and tearDown methods
• Added test for creating the pipeline directory
• Added test for creating the output file

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[h1alexbel]

@rultor merge

[rultor]

@rultor merge

@h1alexbel OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge

@h1alexbel Done! FYI, the full log is here (took me 7min)