Add unit tests for codec inference

[elnaske]

What did you change?

Added unit tests for espnet2/bin/gan_codec_inference.py. Includes tests for end-to-end usage and separate encoding and decoding via the AudioCoding class. Coverage is similar to test scripts for other inference tasks.

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Why did you make this change?

• Existing tests don't cover codec inference.
• I need these tests for a PR I'm working on (see Codec quantization support #6326).

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Is your PR small enough?

Yes (1 file, 50 lines).

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Additional Context

#6326

[gemini-code-assist]

Code Review

This pull request adds unit tests for gan_codec_inference.py. The tests cover the main functionalities, including argument parsing, the main entry point, and the AudioCoding class for encoding and decoding. My main feedback is to strengthen the tests for the AudioCoding class by adding assertions to verify the output, which will make the tests more robust. I've provided a suggestion to combine and improve the existing tests.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.41%. Comparing base (42b49b5) to head (bb15c4a).
⚠️ Report is 74 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6332      +/-   ##
==========================================
+ Coverage   69.39%   69.41%   +0.01%     
==========================================
  Files         759      759              
  Lines       69851    69853       +2     
==========================================
+ Hits        48473    48487      +14     
+ Misses      21378    21366      -12     

Flag	Coverage Δ
test_integration_espnet2	46.96% <ø> (ø)
test_python_espnet2	62.38% <ø> (+0.31%)	⬆️
test_python_espnet3	16.06% <ø> (-0.01%)	⬇️
test_utils	62.38% <ø> (+0.31%)	⬆️

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[Fhrozen]

@elnaske, Thank you for your PR. could you please look the comment from gemini?

[elnaske]

I added the suggested assertions, but decided to keep the test separate to mark the different use cases.

[ftshijt]

Many thanks for your contribution. The test generally looks great. Would be glad to merge after the CIs are passed

[sw005320]

Thanks, @elnaske!