[irozum]

Summary

• Adds unit tests for how PclZip handles zero-byte entries. On PHP 8, fread( $fd, 0 ) throws a ValueError, which @ doesn't suppress.
• This is test-only. It changes nothing under src/ and adds no production behaviour.
• Follow-up to [50355] and [51686], which added the zero-length guards in class-pclzip.php without tests.

Tests added

• Tests_Filesystem_UnzipFilePclzip::test_should_extract_empty_files() runs _unzip_file_pclzip() on the existing archive.zip fixture, which has two zero-byte stored files. It asserts both are extracted and empty. This covers the privExtractFileAsString() guard. The existing tests only checked filter calls.
• Tests_Filesystem_PclZip::test_extract_in_output_should_output_empty_file() extracts an empty entry with PCLZIP_OPT_EXTRACT_IN_OUTPUT. It asserts no output and a correct entry. This covers the privExtractFileInOutput() guard, which nothing exercised before.
• Tests_Filesystem_PclZip::test_create_should_add_empty_file() creates an archive from an empty file (with PCLZIP_OPT_TEMP_FILE_OFF, to reach the in-memory branch) and reads it back. This covers the privAddFile() guard from #54036.

Why these cases

Each test fails with ValueError: fread(): Argument #2 ($length) must be greater than 0 when its guard is reverted (> 0 changed to >= 0), and passes with the guard restored. On PHP 7.4 fread() only warns, so the behavioural assertions hold there too.

Trac ticket: https://core.trac.wordpress.org/ticket/52018

Use of AI Tools

AI assistance: Yes
Tool(s): Claude Code
Model(s): Claude Sonnet 5.5
Used for: Drafting the tests and this description, and running the mutation checks and coding-standards checks.

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