diff --git a/tests/phpunit/tests/Traits/Readme_Utils_Tests.php b/tests/phpunit/tests/Traits/Readme_Utils_Tests.php
new file mode 100644
index 000000000..0b244f893
--- /dev/null
+++ b/tests/phpunit/tests/Traits/Readme_Utils_Tests.php
@@ -0,0 +1,177 @@
+<?php
+/**
+ * Tests for the Readme_Utils trait.
+ *
+ * @package plugin-check
+ */
+
+use WordPress\Plugin_Check\Traits\Readme_Utils;
+
+class Readme_Utils_Tests extends WP_UnitTestCase {
+
+	use Readme_Utils;
+
+	public function test_filter_files_for_readme_with_empty_files_array() {
+		$result = $this->filter_files_for_readme( array(), '/path/to/plugin/' );
+		$this->assertEmpty( $result );
+	}
+
+	public function test_filter_files_for_readme_with_no_readme_files() {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/index.php',
+			'/path/to/plugin/style.css',
+			'/path/to/plugin/includes/class-main.php',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertEmpty( $result );
+	}
+
+	public function test_filter_files_for_readme_with_root_readme_txt() {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/readme.txt',
+			'/path/to/plugin/includes/class-main.php',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertSame( array( 1 => '/path/to/plugin/readme.txt' ), $result );
+	}
+
+	public function test_filter_files_for_readme_with_root_readme_md() {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/readme.md',
+			'/path/to/plugin/includes/class-main.php',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertSame( array( 1 => '/path/to/plugin/readme.md' ), $result );
+	}
+
+	public function test_filter_files_for_readme_prefers_readme_txt_over_readme_md() {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/readme.md',
+			'/path/to/plugin/readme.txt',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertSame( array( 2 => '/path/to/plugin/readme.txt' ), $result );
+	}
+
+	/**
+	 * @dataProvider data_case_variations
+	 */
+	public function test_filter_files_for_readme_case_insensitivity( $readme_file ) {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/' . $readme_file,
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertSame( array( 1 => '/path/to/plugin/' . $readme_file ), $result );
+	}
+
+	public function data_case_variations() {
+		return array(
+			'uppercase TXT'  => array( 'README.TXT' ),
+			'uppercase MD'   => array( 'README.MD' ),
+			'mixed case txt' => array( 'Readme.Txt' ),
+			'mixed case md'  => array( 'Readme.Md' ),
+		);
+	}
+
+	public function test_filter_files_for_readme_ignores_nested_readmes() {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/assets/readme.txt',
+			'/path/to/plugin/vendor/package/readme.md',
+			'/path/to/plugin/docs/readme.txt',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertEmpty( $result );
+	}
+
+	public function test_filter_files_for_readme_with_root_and_nested_readmes() {
+		$files = array(
+			'/path/to/plugin/plugin.php',
+			'/path/to/plugin/assets/readme.txt',
+			'/path/to/plugin/readme.txt',
+			'/path/to/plugin/vendor/package/readme.md',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertSame( array( 2 => '/path/to/plugin/readme.txt' ), $result );
+	}
+
+	public function test_filter_files_for_readme_ignores_non_matching_extensions() {
+		$files = array(
+			'/path/to/plugin/readme.html',
+			'/path/to/plugin/readme.doc',
+			'/path/to/plugin/readme.rst',
+			'/path/to/plugin/readme.php',
+			'/path/to/plugin/readme',
+		);
+
+		$result = $this->filter_files_for_readme( $files, '/path/to/plugin/' );
+		$this->assertEmpty( $result );
+	}
+
+	/**
+	 * @dataProvider data_filter_files_for_readme_scenarios
+	 */
+	public function test_filter_files_for_readme_scenarios( array $files, $plugin_relative_path, array $expected ) {
+		$result = $this->filter_files_for_readme( $files, $plugin_relative_path );
+		$this->assertSame( $expected, $result );
+	}
+
+	public function data_filter_files_for_readme_scenarios() {
+		return array(
+			'standard plugin with readme.txt'      => array(
+				array(
+					'/var/www/html/wp-content/plugins/sample-plugin/sample-plugin.php',
+					'/var/www/html/wp-content/plugins/sample-plugin/readme.txt',
+					'/var/www/html/wp-content/plugins/sample-plugin/uninstall.php',
+				),
+				'/var/www/html/wp-content/plugins/sample-plugin/',
+				array(
+					1 => '/var/www/html/wp-content/plugins/sample-plugin/readme.txt',
+				),
+			),
+			'plugin with only readme.md'           => array(
+				array(
+					'/var/www/html/wp-content/plugins/sample-plugin/sample-plugin.php',
+					'/var/www/html/wp-content/plugins/sample-plugin/readme.md',
+				),
+				'/var/www/html/wp-content/plugins/sample-plugin/',
+				array(
+					1 => '/var/www/html/wp-content/plugins/sample-plugin/readme.md',
+				),
+			),
+			'plugin with both text and md at root' => array(
+				array(
+					'/var/www/html/wp-content/plugins/sample-plugin/readme.md',
+					'/var/www/html/wp-content/plugins/sample-plugin/readme.txt',
+				),
+				'/var/www/html/wp-content/plugins/sample-plugin/',
+				array(
+					1 => '/var/www/html/wp-content/plugins/sample-plugin/readme.txt',
+				),
+			),
+			'deeply nested path structure'         => array(
+				array(
+					'/app/web/wp/wp-content/plugins/advanced-tool/advanced-tool.php',
+					'/app/web/wp/wp-content/plugins/advanced-tool/readme.txt',
+					'/app/web/wp/wp-content/plugins/advanced-tool/sub/readme.txt',
+				),
+				'/app/web/wp/wp-content/plugins/advanced-tool/',
+				array(
+					1 => '/app/web/wp/wp-content/plugins/advanced-tool/readme.txt',
+				),
+			),
+		);
+	}
+}