Tests: Add unit test coverage for Readme_Utils trait

[noruzzamans]

What?

Adds comprehensive unit test coverage for the WordPress\Plugin_Check\Traits\Readme_Utils trait in tests/phpunit/tests/Traits/Readme_Utils_Tests.php.

Why?

The Readme_Utils trait provides essential file-filtering and prioritization logic used across core plugin checks:

• WordPress\Plugin_Check\Plugin_Context
• WordPress\Plugin_Check\Checker\Checks\Plugin_Repo\Plugin_Readme_Check
• WordPress\Plugin_Check\Checker\Checks\Plugin_Repo\Plugin_Header_Fields_Check
• WordPress\Plugin_Check\Checker\Checks\Plugin_Repo\Trademarks_Check

While other utility traits in includes/Traits/ (such as Language_Utils, Version_Utils, License_Utils, and Amend_DB_Base_Prefix) have dedicated unit tests in tests/phpunit/tests/Traits/, Readme_Utils lacked isolated unit test coverage. Adding unit test coverage ensures its filtering logic, root-path resolution, and readme precedence rules remain reliable and regression-free.

How?

Introduced tests/phpunit/tests/Traits/Readme_Utils_Tests.php with 16 tests and 16 assertions covering:

1. test_filter_files_for_readme_with_empty_files_array: returns an empty array when given an empty list of files.
2. test_filter_files_for_readme_with_no_readme_files: returns an empty array when no readme files are present in the list.
3. test_filter_files_for_readme_with_root_readme_txt: correctly detects and returns root-level readme.txt.
4. test_filter_files_for_readme_with_root_readme_md: correctly detects and returns root-level readme.md when no readme.txt exists.
5. test_filter_files_for_readme_prefers_readme_txt_over_readme_md: verifies that readme.txt takes precedence over readme.md when both exist at root.
6. test_filter_files_for_readme_case_insensitivity: verifies case-insensitive detection (README.TXT, README.MD, Readme.Txt, Readme.Md).
7. test_filter_files_for_readme_ignores_nested_readmes: verifies that readme files located in subdirectories (e.g. assets/readme.txt, vendor/package/readme.md, docs/readme.txt) are excluded.
8. test_filter_files_for_readme_with_root_and_nested_readmes: verifies root readme is selected while nested readmes are filtered out.
9. test_filter_files_for_readme_ignores_non_matching_extensions: verifies that files like readme.html, readme.doc, readme.rst, and readme.php are ignored.
10. test_filter_files_for_readme_scenarios: data provider covering realistic file structures and various paths.

Note: This is a 100% test-only contribution with 0 modifications to production code.

Testing Instructions

1. Run the PHPUnit test suite:

phpunit tests/phpunit/tests/Traits/Readme_Utils_Tests.php

Expected Output:

PHPUnit 9.6.34 by Sebastian Bergmann and contributors.

................                                                  16 / 16 (100%)

Time: 00:00.015, Memory: 42.50 MB

OK (16 tests, 16 assertions)

2. Run coding standards linter (PHPCS):

composer lint tests/phpunit/tests/Traits/Readme_Utils_Tests.php

Expected Output:

. 1 / 1 (100%)
Time: 70ms; Memory: 18MB

3. Run static analysis (PHPStan):

composer phpstan

Expected Output:

[OK] No errors

Use of AI Tools

• AI assistance: Yes
• Model(s): Gemini 3.8 Flash High
• Used for: Identifying test coverage gaps in includes/Traits/Readme_Utils.php, structuring test cases conforming to WP_UnitTestCase patterns, and formatting testing instructions. Final implementation was reviewed, tested, and verified locally.

[github-actions]

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Co-authored-by: noruzzamans <noruzzaman@git.wordpress.org>

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[Copilot]

🟢 Approval recommended

The test-only change has no blocking issues; only a minor style nit remains.

Pull request overview

Adds PHPUnit coverage for the Readme_Utils trait’s readme filtering and precedence behavior.

Changes:

• Tests root detection, .txt precedence, casing, nesting, and invalid extensions.
• Adds realistic data-driven path scenarios.

File summaries

File	Description
tests/phpunit/tests/Traits/Readme_Utils_Tests.php	Adds 16 unit tests for readme filtering.

Review note: Remove redundant PHPDoc blocks to follow project test-file guidance (nit).

Review details

Suppressed comments (1)

tests/phpunit/tests/Traits/Readme_Utils_Tests.php:6

• The repository's test-file guidance explicitly excludes PHPDoc blocks for unit-test files, classes, and methods, but this file adds them throughout (including this header). Please remove the redundant test docblocks so the new test follows the established PHPUnit style and the project guideline.

/**
 * Tests for the Readme_Utils trait.
 *
 * @package plugin-check
 */

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

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[noruzzamans]

Updated in f25c5d7b:

• Removed redundant class, test method, and data provider PHPDoc blocks to align with repository conventions in tests/phpunit/tests/Traits/.
• Retained @dataProvider annotations on parameterized tests.
• Re-verified that all local PHPUnit tests (16/16), PHPCS, and PHPStan checks pass cleanly.