Help improve test coverage

[cedsic]

PyAI Extract & Summarize has some basic tests, but we could use help adding more tests to ensure the code works correctly with different file types and edge cases.

Tasks for contributors:

1. Add tests for empty files (PDF, CSV, XLSX, images).
2. Add tests for unsupported file types to ensure proper errors are raised.
3. Add tests for .txt files (if implemented).
4. Add additional test cases for summarization limits (e.g., very short or very long text).

Tests are written using pytest and located in test_core.py.
You can run tests with:

pytest

[bmislol]

Hi, I'm a new contributor and would like to try and help with this issue. Can I be assigned?