Fix range requests returning excess data in file_stream()

[ChihweiLHBird]

Summary

• Fix file_stream() sending more bytes than requested for range requests when the range size is not aligned to chunk_size
• The streaming loop used _range.size (a constant) instead of to_send (which decreases each iteration), causing over-reads on subsequent chunks
• Add regression test verifying correct body length for multi-chunk range requests
• Add get_file_size() test helper using stat() instead of reading entire file contents

Fixes #2507

Test plan

• Existing test_file_stream_response_range tests pass
• New test_file_stream_response_range_correct_length test verifies a 100-byte range with 32-byte chunks returns exactly 100 bytes
• Static content range tests pass

[Copilot]

Pull request overview

Fixes an over-read bug in Sanic’s file_stream() range-response streaming loop that could send more bytes than requested when the range length is not aligned with chunk_size, and adds a regression test to lock in the correct behavior.

Changes:

• Correct range streaming to read min(to_send, chunk_size) per iteration (instead of a constant range size).
• Add a regression test asserting a multi-chunk range response returns the exact requested byte length.
• Add a test helper to compute file sizes via stat() rather than reading whole files.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
sanic/response/convenience.py	Fix range streaming loop to prevent sending excess bytes on multi-chunk range reads.
tests/test_response.py	Add regression test for correct range body length and introduce get_file_size() helper used by range tests.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.731%. Comparing base (785d77f) to head (2262ed1).

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3150       +/-   ##
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- Coverage   87.793%   87.731%   -0.062%     
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  Files          105       105               
  Lines         8143      8143               
  Branches      1290      1290               
=============================================
- Hits          7149      7144        -5     
- Misses         687       692        +5     
  Partials       307       307               

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