Introduce an interface so all schemas implement the same

lib/class-wp-theme-json-schema-v0.php

@@ -1,15 +1,16 @@
 <?php
 /**
- * Processes structures that adhere to the theme.json schema V0.
+ * Class that implements a WP_Theme_JSON_Schema to convert
+ * a given structure in v0 schema to the latest one.
  *
  * @package gutenberg
  */
 
 /**
- * Class that encapsulates the processing of
- * structures that adhere to the theme.json V0.
+ * Class that implements a WP_Theme_JSON_Schema to convert
+ * a given structure in v0 schema to the latest one.
  */
-class WP_Theme_JSON_Schema_V0 {
+class WP_Theme_JSON_Schema_V0 implements WP_Theme_JSON_Schema {
 
 	/**
 	 * How to address all the blocks
@@ -121,13 +122,13 @@ class WP_Theme_JSON_Schema_V0 {
 	);
 
 	/**
-	 * Utility to convert v0 schemas into v1.
+	 * Converts a v0 schema into the latest.
 	 *
-	 * @param array $old A theme.json in v0 format.
+	 * @param array $old Data in v0 schema.
 	 *
-	 * @return array The new theme.json in the v1 format.
+	 * @return array Data in the latest schema.
 	 */
-	public static function to_v1( $old ) {
+	public static function parse( $old ) {
 		// Copy everything.
 		$new = $old;
 

lib/interface-wp-theme-json-schema.php

@@ -0,0 +1,18 @@
+<?php
+/**
+ * Schema interface for theme.json structures.
+ *
+ * @package gutenberg
+ */
+
+interface WP_Theme_JSON_Schema {
+	/**
+	 * Parses an array that follows an old theme.json schema
+	 * into the latest theme.json schema.
+	 *
+	 * @param array $theme_json Old data to convert.
+	 *
+	 * @return array The data in the latest theme.json schema.
+	 */
+	public static function parse( $theme_json );
+}

lib/load.php

@@ -89,6 +89,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 
 // These are used by some FSE features
 // as well as global styles.
+require __DIR__ . '/interface-wp-theme-json-schema.php';
 require __DIR__ . '/class-wp-theme-json-schema-v0.php';
 require __DIR__ . '/class-wp-theme-json.php';
 require __DIR__ . '/class-wp-theme-json-resolver.php';

phpunit/class-wp-theme-json-schema-v0-test.php

@@ -8,7 +8,7 @@
 
 class WP_Theme_JSON_Schema_V0_Test extends WP_UnitTestCase {
 
-	function test_schema_to_v1() {
+	function test_parse() {
 		$theme_json_v0 = array(
 			'settings' => array(
 				'defaults'       => array(
@@ -85,7 +85,8 @@ function test_schema_to_v1() {
 				),
 			),
 		);
-		$theme_json_v1 = WP_Theme_JSON_Schema_V0::to_v1( $theme_json_v0 );
+
+		$actual = WP_Theme_JSON_Schema_V0::parse( $theme_json_v0 );
 
 		$expected = array(
 			'version'  => 1,
@@ -150,6 +151,6 @@ function test_schema_to_v1() {
 			),
 		);
 
-		$this->assertEqualSetsWithIndex( $expected, $theme_json_v1 );
+		$this->assertEqualSetsWithIndex( $expected, $actual );
 	}
 }