Font Library: delete child font faces and font assets when deleting parent

lib/experimental/fonts/font-library/font-library.php

@@ -187,3 +187,60 @@
 		return apply_filters( 'font_dir', $defaults );
 	}
 }
+
+// @core-merge: Filters should go in `src/wp-includes/default-filters.php`,
+// functions in a general file for font library.
+if ( ! function_exists( '_wp_deleted_font_family' ) ) {
+	/**
+	 * Deletes child font faces when a font family is deleted.
+	 *
+	 * @access private
+	 * @since 6.5.0
+	 *
+	 * @param int     $post_id Post ID.
+	 * @param WP_Post $post    Post object.
+	 * @return void
+	 */
+	function _wp_delete_font_family( $post_id, $post ) {
+		if ( 'wp_font_family' !== $post->post_type ) {
+			return;
+		}
+
+		$font_faces = get_children(
+			array(
+				'post_parent' => $post_id,
+				'post_type'   => 'wp_font_face',
+			)
+		);
+
+		foreach ( $font_faces as $font_face ) {
+			wp_delete_post( $font_face->ID, true );
+		}
+	}
+	add_action( 'deleted_post', '_wp_delete_font_family', 10, 2 );
+}
+
+if ( ! function_exists( '_wp_delete_font_face' ) ) {
+	/**
+	 * Deletes associated font files when a font face is deleted.
+	 *
+	 * @access private
+	 * @since 6.5.0
+	 *
+	 * @param int     $post_id Post ID.
+	 * @param WP_Post $post    Post object.
+	 * @return void
+	 */
+	function _wp_delete_font_face( $post_id, $post ) {
+		if ( 'wp_font_face' !== $post->post_type ) {
+			return;
+		}
+
+		$font_files = get_post_meta( $post_id, '_wp_font_face_files', false );
+
+		foreach ( $font_files as $font_file ) {
+			wp_delete_file( wp_get_font_dir()['path'] . '/' . $font_file );
+		}
+	}
+	add_action( 'before_delete_post', '_wp_delete_font_face', 10, 2 );
+}

phpunit/tests/fonts/font-library/fontLibraryHooks.php

@@ -0,0 +1,85 @@
+<?php
+/**
+ * Test deleting wp_font_family and wp_font_face post types.
+ *
+ * @package WordPress
+ * @subpackage Font Library
+ */
+
+class Tests_Font_Library_Hooks extends WP_UnitTestCase {
+	public function test_deleting_font_family_deletes_child_font_faces() {
+		$font_family_id       = self::factory()->post->create(
+			array(
+				'post_type' => 'wp_font_family',
+			)
+		);
+		$font_face_id         = self::factory()->post->create(
+			array(
+				'post_type'   => 'wp_font_face',
+				'post_parent' => $font_family_id,
+			)
+		);
+		$other_font_family_id = self::factory()->post->create(
+			array(
+				'post_type' => 'wp_font_family',
+			)
+		);
+		$other_font_face_id   = self::factory()->post->create(
+			array(
+				'post_type'   => 'wp_font_face',
+				'post_parent' => $other_font_family_id,
+			)
+		);
+
+		wp_delete_post( $font_family_id, true );
+
+		$this->assertNull( get_post( $font_face_id ) );
+		$this->assertNotNull( get_post( $other_font_face_id ) );
+	}
+
+	public function test_deleting_font_faces_deletes_associated_font_files() {
+		list( $font_face_id, $font_path ) = $this->create_font_face_with_file( 'OpenSans-Regular.woff2' );
+		list( , $other_font_path )        = $this->create_font_face_with_file( 'OpenSans-Regular.ttf' );
+
+		wp_delete_post( $font_face_id, true );
+
+		$this->assertFalse( file_exists( $font_path ) );
+		$this->assertTrue( file_exists( $other_font_path ) );
+	}
+
+	protected function create_font_face_with_file( $filename ) {
+		$font_face_id = self::factory()->post->create(
+			array(
+				'post_type' => 'wp_font_face',
+			)
+		);
+
+		$font_file = $this->upload_font_file( $filename );
+
+		// Make sure the font file uploaded successfully.
+		$this->assertFalse( $font_file['error'] );
+
+		$font_path     = $font_file['file'];
+		$font_filename = basename( $font_path );
+		add_post_meta( $font_face_id, '_wp_font_face_files', $font_filename );
+
+		return array( $font_face_id, $font_path );
+	}
+
+	protected function upload_font_file( $font_filename ) {
+		// @core-merge Use `DIR_TESTDATA` instead of `GUTENBERG_DIR_TESTDATA`.
+		$font_file_path = GUTENBERG_DIR_TESTDATA . 'fonts/' . $font_filename;
+
+		add_filter( 'upload_mimes', array( 'WP_Font_Library', 'set_allowed_mime_types' ) );
+		add_filter( 'upload_dir', 'wp_get_font_dir' );
+		$font_file = wp_upload_bits(
+			$font_filename,
+			null,
+			file_get_contents( $font_file_path )
+		);
+		remove_filter( 'upload_dir', 'wp_get_font_dir' );
+		remove_filter( 'upload_mimes', array( 'WP_Font_Library', 'set_allowed_mime_types' ) );
+
+		return $font_file;
+	}
+}

phpunit/tests/fonts/font-library/wpRestFontFamiliesController.php

@@ -700,12 +700,11 @@ protected function check_font_family_data( $data, $post_id, $links ) {
 		$this->assertArrayHasKey( 'theme_json_version', $data );
 		$this->assertSame( WP_Theme_JSON::LATEST_SCHEMA, $data['theme_json_version'] );
 
-		$font_face_ids = get_posts(
+		$font_face_ids = get_children(
 			array(
-				'fields'         => 'ids',
-				'post_parent'    => $post_id,
-				'post_type'      => 'wp_font_face',
-				'posts_per_page' => 999,
+				'fields'      => 'ids',
+				'post_parent' => $post_id,
+				'post_type'   => 'wp_font_face',
 			)
 		);
 		$this->assertArrayHasKey( 'font_faces', $data );