Remove failed attempt to use non-erasable output buffer

On some hosting configurations, the WP object cache is not available in the callback at shutdown.

Also fix some new unit test assertion failures.

includes/class-amp-theme-support.php

@@ -261,11 +261,7 @@ public static function add_hooks() {
 		 * Start output buffering at very low priority for sake of plugins and themes that use template_redirect
 		 * instead of template_include.
 		 */
-		add_action( 'template_redirect', function() {
-			AMP_Theme_Support::start_output_buffering( array(
-				'cancelable' => class_exists( 'WP_UnitTestCase' ),
-			) );
-		} );
+		add_action( 'template_redirect', array( __CLASS__, 'start_output_buffering' ), 0 );
 
 		// Commenting hooks.
 		add_filter( 'wp_list_comments_args', array( __CLASS__, 'set_comments_walker' ), PHP_INT_MAX );
@@ -967,21 +963,8 @@ public static function dequeue_customize_preview_scripts() {
 	 *
 	 * @since 0.7
 	 * @see AMP_Theme_Support::finish_output_buffering()
-	 *
-	 * @param array $args {
-	 *     Args.
-	 *
-	 *     @type bool $cancelable Whether the output buffer can be flushed/removed/cleaned.
-	 * }
 	 */
-	public static function start_output_buffering( $args = array() ) {
-		$args = array_merge(
-			array(
-				'cancelable' => true, // Must be cancelable during unit tests.
-			),
-			$args
-		);
-
+	public static function start_output_buffering() {
 		/*
 		 * Disable the New Relic Browser agent on AMP responses.
 		 * This prevents th New Relic from causing invalid AMP responses due the NREUM script it injects after the meta charset:
@@ -993,19 +976,7 @@ public static function start_output_buffering( $args = array() ) {
 			newrelic_disable_autorum();
 		}
 
-		$chunk_size = 0; // Default value.
-		if ( defined( 'PHP_OUTPUT_HANDLER_STDFLAGS' ) ) {
-			$erase_flags = $args['cancelable'] ? PHP_OUTPUT_HANDLER_STDFLAGS : 0; // phpcs:ignore PHPCompatibility.PHP.NewConstants.php_output_handler_stdflagsFound
-		} else {
-			$erase_flags = ! $args['cancelable'];
-		}
-		ob_start( array( __CLASS__, 'finish_output_buffering' ), $chunk_size, $erase_flags );
-
-		/*
-		 * Remove shutdown flushing which will cause PHP notice since buffer is not flushable.
-		 * This was only needed in PHP 5.2 anyway, which this plugin does not support.
-		 */
-		remove_action( 'shutdown', 'wp_ob_end_flush_all', 1 );
+		ob_start( array( __CLASS__, 'finish_output_buffering' ) );
 	}
 
 	/**

tests/test-class-amp-theme-support.php

@@ -34,6 +34,7 @@ public function tearDown() {
 		$_SERVER['QUERY_STRING'] = '';
 		unset( $_SERVER['REQUEST_URI'] );
 		unset( $_SERVER['REQUEST_METHOD'] );
+		unset( $GLOBALS['content_width'] );
 		if ( isset( $GLOBALS['wp_customize'] ) ) {
 			$GLOBALS['wp_customize']->stop_previewing_theme();
 		}
@@ -605,16 +606,19 @@ public function test_register_widgets() {
 	 * Test register_content_embed_handlers.
 	 *
 	 * @covers AMP_Theme_Support::register_content_embed_handlers()
+	 * @global int $content_width
 	 */
 	public function test_register_content_embed_handlers() {
+		global $content_width;
+		$content_width  = 1234;
 		$embed_handlers = AMP_Theme_Support::register_content_embed_handlers();
 		foreach ( $embed_handlers as $embed_handler ) {
 			$this->assertTrue( is_subclass_of( $embed_handler, 'AMP_Base_Embed_Handler' ) );
 			$reflection = new ReflectionObject( $embed_handler );
 			$args       = $reflection->getProperty( 'args' );
 			$args->setAccessible( true );
 			$property = $args->getValue( $embed_handler );
-			$this->assertEquals( AMP_Post_Template::CONTENT_MAX_WIDTH, $property['content_max_width'] );
+			$this->assertEquals( $content_width, $property['content_max_width'] );
 		}
 	}
 
@@ -892,7 +896,6 @@ function newrelic_disable_autorum() {
 		$ob_level = ob_get_level();
 		AMP_Theme_Support::start_output_buffering();
 
-		$this->assertEquals( 0, has_action( 'shutdown', array( self::TESTED_CLASS, 'finish_output_buffering' ) ) );
 		$this->assertTrue( ob_get_level() > $ob_level );
 
 		// End output buffer.
@@ -987,7 +990,10 @@ public function test_prepare_response() {
 			echo '<!-- wp_print_scripts -->';
 		} );
 		add_filter( 'script_loader_tag', function( $tag, $handle ) {
-			return preg_replace( '/(?<=<script)/', " handle='$handle' ", $tag );
+			if ( ! wp_scripts()->get_data( $handle, 'conditional' ) ) {
+				$tag = preg_replace( '/(?<=<script)/', " handle='$handle' ", $tag );
+			}
+			return $tag;
 		}, 10, 2 );
 		add_action( 'wp_footer', function() {
 			wp_print_scripts( 'amp-mathml' );