Multimodal - audio tests

[debroy-rh]

Test Plan:

Unit tests for - vllm/multimodal/audio.py
The tests validate audio resampling (librosa, scipy) and ensure AudioResampler correctly delegates to the right backend, raises errors for invalid methods, and enforces target sample rates. They also verify AudioMediaIO can load audio from bytes, base64, and file paths, and encode audio to base64, with external libraries mocked (librosa, soundfile). Assertions check correct function calls, expected outputs, and error handling.

[gemini-code-assist]

Code Review

This pull request introduces unit tests for audio processing functionalities in vllm/multimodal/audio.py. The tests are well-structured, covering resampling and media I/O operations with appropriate mocking. My review identifies a critical gap in the test coverage for resample_audio_scipy. The current tests only validate scenarios with integer resampling ratios, failing to detect a bug in the implementation that causes incorrect resampling for non-integer ratios. I've suggested an additional test case to expose and address this correctness issue.

[DarkLight1337]

Thanks for adding these tests!

Make sure you run pip-compile to update the requirements/test.txt file

[debroy-rh]

spicy is already added to requirements/test.txt. so I removed it from requirements/test.in.