Add unit tests.

tests/phpunit/tests/rest-api/rest-global-styles-revisions-controller.php

@@ -326,6 +326,21 @@ public function test_get_items() {
 		$this->check_get_revision_response( $data[2], $this->revision_1 );
 	}
 
+	/**
+	 * @ticket 56481
+	 *
+	 * @covers WP_REST_Global_Styles_Controller::prepare_item_for_response
+	 *
+	 * @param string $method The HTTP method to use.
+	 */
+	public function test_get_items_should_return_no_response_body_for_head_requests() {
+		wp_set_current_user( self::$admin_id );
+		$request  = new WP_REST_Request( 'HEAD', '/wp/v2/global-styles/' . self::$global_styles_id . '/revisions' );
+		$response = rest_get_server()->dispatch( $request );
+		$this->assertSame( 200, $response->get_status(), 'Response status is 200.' );
+		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
+	}
+
 	/**
 	 * @ticket 59810
 	 *
@@ -342,6 +357,21 @@ public function test_get_item() {
 		$this->check_get_revision_response( $data, $this->revision_1 );
 	}
 
+	/**
+	 * @ticket 56481
+	 *
+	 * @covers WP_REST_Global_Styles_Controller::prepare_item_for_response
+	 *
+	 * @param string $method The HTTP method to use.
+	 */
+	public function test_get_item_should_return_no_response_body_for_head_requests() {
+		wp_set_current_user( self::$admin_id );
+		$request  = new WP_REST_Request( 'HEAD', '/wp/v2/global-styles/' . self::$global_styles_id . '/revisions/' . $this->revision_1_id );
+		$response = rest_get_server()->dispatch( $request );
+		$this->assertSame( 200, $response->get_status(), 'Response status is 200.' );
+		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
+	}
+
 	/**
 	 * @dataProvider data_readable_http_methods
 	 * @ticket 59810