diff --git a/tests/phpunit/tests/link/permalinkAnchor.php b/tests/phpunit/tests/link/permalinkAnchor.php
new file mode 100644
index 0000000000000..5d9d05091804d
--- /dev/null
+++ b/tests/phpunit/tests/link/permalinkAnchor.php
@@ -0,0 +1,152 @@
+<?php
+/**
+ * Tests for the `permalink_anchor()` function.
+ *
+ * @group link
+ * @group post
+ *
+ * @covers ::permalink_anchor
+ */
+class Tests_Link_PermalinkAnchor extends WP_UnitTestCase {
+
+	/**
+	 * Test post ID.
+	 *
+	 * @var int
+	 */
+	protected static $post_id;
+
+	/**
+	 * Sets up shared fixtures for the test class.
+	 *
+	 * @param WP_UnitTest_Factory $factory Unit test factory.
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		self::$post_id = $factory->post->create(
+			array(
+				'post_title' => 'Test Post Title',
+			)
+		);
+	}
+
+	/**
+	 * Sets up the global $post object before each test method.
+	 */
+	public function set_up() {
+		parent::set_up();
+		$GLOBALS['post'] = get_post( self::$post_id );
+	}
+
+	/**
+	 * Tears down the global $post object after each test method.
+	 */
+	public function tear_down() {
+		unset( $GLOBALS['post'] );
+		parent::tear_down();
+	}
+
+	/**
+	 * Tests that permalink_anchor() outputs the post ID anchor by default when no argument is passed.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_permalink_anchor_default_mode_id() {
+		$expected = '<a id="post-' . self::$post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor' ) );
+	}
+
+	/**
+	 * Tests that permalink_anchor() outputs the post ID anchor when explicitly passing 'id'.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_permalink_anchor_explicit_mode_id() {
+		$expected = '<a id="post-' . self::$post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'id' ) ) );
+	}
+
+	/**
+	 * Tests that permalink_anchor() handles mode case-insensitively for 'id'.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_permalink_anchor_mode_id_case_insensitive() {
+		$expected = '<a id="post-' . self::$post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'ID' ) ) );
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'Id' ) ) );
+	}
+
+	/**
+	 * Tests that permalink_anchor() outputs the sanitized title anchor when passing 'title'.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_permalink_anchor_mode_title() {
+		$expected = '<a id="test-post-title-' . self::$post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'title' ) ) );
+	}
+
+	/**
+	 * Tests that permalink_anchor() handles mode case-insensitively for 'title'.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_permalink_anchor_mode_title_case_insensitive() {
+		$expected = '<a id="test-post-title-' . self::$post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'TITLE' ) ) );
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'Title' ) ) );
+	}
+
+	/**
+	 * Tests that permalink_anchor() properly sanitizes titles containing special characters.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_permalink_anchor_mode_title_with_special_characters() {
+		$special_post_id = self::factory()->post->create(
+			array(
+				'post_title' => 'Special Characters & Symbols: 100% Valid!',
+			)
+		);
+
+		$GLOBALS['post'] = get_post( $special_post_id );
+
+		$expected = '<a id="special-characters-symbols-100-valid-' . $special_post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( 'title' ) ) );
+	}
+
+	/**
+	 * Tests that permalink_anchor() falls back to id mode for unrecognized mode arguments.
+	 *
+	 * @ticket 65819
+	 *
+	 * @dataProvider data_unrecognized_modes
+	 *
+	 * @param string $mode Mode to pass.
+	 */
+	public function test_permalink_anchor_unrecognized_mode_falls_back_to_id( $mode ) {
+		$expected = '<a id="post-' . self::$post_id . '"></a>';
+
+		$this->assertSame( $expected, get_echo( 'permalink_anchor', array( $mode ) ) );
+	}
+
+	/**
+	 * Data provider for test_permalink_anchor_unrecognized_mode_falls_back_to_id().
+	 *
+	 * @return array[]
+	 */
+	public static function data_unrecognized_modes() {
+		return array(
+			'empty string'        => array( '' ),
+			'arbitrary string'    => array( 'custom' ),
+			'invalid mode slug'   => array( 'slug' ),
+			'numeric string mode' => array( '123' ),
+		);
+	}
+}