Merge pull request #1822 from WordPress/fix/short-circuit-rest-api-unavailable

Ensure optimization is performed in the wp-env local environment and log debug messages to console when disabled

Author: westonruter

plugins/optimization-detective/optimization.php

@@ -80,14 +80,38 @@ static function ( string $output, ?int $phase ): string {
  * @access private
  */
 function od_maybe_add_template_output_buffer_filter(): void {
-	if (
-		! od_can_optimize_response() ||
-		od_is_rest_api_unavailable() ||
-		isset( $_GET['optimization_detective_disabled'] ) // phpcs:ignore WordPress.Security.NonceVerification.Recommended
-
-	) {
+	$conditions = array(
+		array(
+			'test'   => od_can_optimize_response(),
+			'reason' => __( 'Page is not optimized because od_can_optimize_response() returned false. This can be overridden with the od_can_optimize_response filter.', 'optimization-detective' ),
+		),
+		array(
+			'test'   => ! od_is_rest_api_unavailable() || ( wp_get_environment_type() === 'local' && ! function_exists( 'tests_add_filter' ) ),
+			'reason' => __( 'Page is not optimized because the REST API for storing URL Metrics is not available.', 'optimization-detective' ),
+		),
+		array(
+			'test'   => ! isset( $_GET['optimization_detective_disabled'] ), // phpcs:ignore WordPress.Security.NonceVerification.Recommended
+			'reason' => __( 'Page is not optimized because the URL has the optimization_detective_disabled query parameter.', 'optimization-detective' ),
+		),
+	);
+	$reasons    = array();
+	foreach ( $conditions as $condition ) {
+		if ( ! $condition['test'] ) {
+			$reasons[] = $condition['reason'];
+		}
+	}
+	if ( count( $reasons ) > 0 ) {
+		if ( WP_DEBUG ) {
+			add_action(
+				'wp_print_footer_scripts',
+				static function () use ( $reasons ): void {
+					od_print_disabled_reasons( $reasons );
+				}
+			);
+		}
 		return;
 	}
+
 	$callback = 'od_optimize_template_output_buffer';
 	if (
 		function_exists( 'perflab_wrap_server_timing' )
@@ -101,6 +125,28 @@ function_exists( 'perflab_server_timing_use_output_buffer' )
 	add_filter( 'od_template_output_buffer', $callback );
 }
 
+/**
+ * Prints the reasons why Optimization Detective is not optimizing the current page.
+ *
+ * This is only used when WP_DEBUG is enabled.
+ *
+ * @since n.e.x.t
+ * @access private
+ *
+ * @param string[] $reasons Reason messages.
+ */
+function od_print_disabled_reasons( array $reasons ): void {
+	foreach ( $reasons as $reason ) {
+		wp_print_inline_script_tag(
+			sprintf(
+				'console.info( %s );',
+				(string) wp_json_encode( '[Optimization Detective] ' . $reason )
+			),
+			array( 'type' => 'module' )
+		);
+	}
+}
+
 /**
  * Determines whether the current response can be optimized.
  *

plugins/optimization-detective/tests/test-optimization.php

@@ -215,6 +215,25 @@ public function test_od_maybe_add_template_output_buffer_filter( Closure $set_up
 		$this->assertSame( $expected_has_filter, has_filter( 'od_template_output_buffer' ) );
 	}
 
+	/**
+	 * Test od_print_disabled_reasons().
+	 *
+	 * @covers ::od_print_disabled_reasons
+	 */
+	public function test_od_print_disabled_reasons(): void {
+		$this->assertSame( '', get_echo( 'od_print_disabled_reasons', array( array() ) ) );
+		$foo_message = get_echo( 'od_print_disabled_reasons', array( array( 'Foo' ) ) );
+		$this->assertStringContainsString( '<script', $foo_message );
+		$this->assertStringContainsString( 'console.info(', $foo_message );
+		$this->assertStringContainsString( '[Optimization Detective] Foo', $foo_message );
+
+		$foo_and_bar_messages = get_echo( 'od_print_disabled_reasons', array( array( 'Foo', 'Bar' ) ) );
+		$this->assertStringContainsString( '<script', $foo_and_bar_messages );
+		$this->assertStringContainsString( 'console.info(', $foo_and_bar_messages );
+		$this->assertStringContainsString( '[Optimization Detective] Foo', $foo_and_bar_messages );
+		$this->assertStringContainsString( '[Optimization Detective] Bar', $foo_and_bar_messages );
+	}
+
 	/**
 	 * Data provider.
 	 *