Block Hooks: Suppress insertion of hooked blocks in before/after position into post object content

src/wp-includes/blocks.php

@@ -1248,8 +1248,25 @@
 		$content
 	);
 
+	/*
+	 * We need to avoid inserting any blocks hooked into the `before` and `after` positions
+	 * of the temporary wrapper block that we create to wrap the content.
+	 * See https://core.trac.wordpress.org/ticket/63287 for more details.
+	 */
+	$suppress_blocks_from_insertion_before_and_after_wrapper_block = static function ( $hooked_block_types, $relative_position, $anchor_block_type ) use ( $wrapper_block_type ) {
+		if (
+			$wrapper_block_type === $anchor_block_type &&
+			in_array( $relative_position, array( 'before', 'after' ), true )
+		) {
+			return array();
+		}
+		return $hooked_block_types;
+	};
+
 	// Apply Block Hooks.
+	add_filter( 'hooked_block_types', $suppress_blocks_from_insertion_before_and_after_wrapper_block, PHP_INT_MAX, 3);
 	$content = apply_block_hooks_to_content( $content, $post, $callback );
+	remove_filter( 'hooked_block_types', $suppress_blocks_from_insertion_before_and_after_wrapper_block, PHP_INT_MAX );
 
 	// Finally, we need to remove the temporary wrapper block.
 	$content = remove_serialized_parent_block( $content );

tests/phpunit/tests/blocks/applyBlockHooksToContent.php

@@ -17,13 +17,14 @@ class Tests_Blocks_ApplyBlockHooksToContent extends WP_UnitTestCase {
 	 * Set up.
 	 *
 	 * @ticket 61902.
+	 * @ticket 63287.
 	 */
 	public static function wpSetUpBeforeClass() {
 		register_block_type(
 			'tests/hooked-block',
 			array(
 				'block_hooks' => array(
-					'tests/anchor-block' => 'after',
+					'core/post-content' => 'after',
 				),
 			)
 		);
@@ -79,23 +80,25 @@ public function test_apply_block_hooks_to_content_sets_theme_attribute_on_templa
 
 	/**
 	 * @ticket 61902
+	 * @ticket 63287
 	 */
 	public function test_apply_block_hooks_to_content_inserts_hooked_block() {
 		$context          = new WP_Block_Template();
-		$context->content = '<!-- wp:tests/anchor-block /-->';
+		$context->content = '<!-- wp:post-content /-->';
 
 		$actual = apply_block_hooks_to_content( $context->content, $context, 'insert_hooked_blocks' );
 		$this->assertSame(
-			'<!-- wp:tests/anchor-block /--><!-- wp:tests/hooked-block /-->',
+			'<!-- wp:post-content /--><!-- wp:tests/hooked-block /-->',
 			$actual
 		);
 	}
 
 	/**
 	 * @ticket 61074
+	 * @ticket 63287
 	 */
 	public function test_apply_block_hooks_to_content_with_context_set_to_null() {
-		$content = '<!-- wp:tests/anchor-block /-->';
+		$content = '<!-- wp:post-content /-->';
 
 		/*
 		 * apply_block_hooks_to_content() will fall back to the global $post object (via get_post())
@@ -106,7 +109,7 @@ public function test_apply_block_hooks_to_content_with_context_set_to_null() {
 
 		$actual = apply_block_hooks_to_content( $content, null, 'insert_hooked_blocks' );
 		$this->assertSame(
-			'<!-- wp:tests/anchor-block /--><!-- wp:tests/hooked-block /-->',
+			'<!-- wp:post-content /--><!-- wp:tests/hooked-block /-->',
 			$actual
 		);
 	}

tests/phpunit/tests/blocks/applyBlockHooksToContentFromPostObject.php

@@ -88,6 +88,15 @@ public static function wpSetUpBeforeClass() {
 				),
 			)
 		);
+
+		register_block_type(
+			'tests/hooked-block-after-post-content',
+			array(
+				'block_hooks' => array(
+					'core/post-content' => 'after',
+				),
+			)
+		);
 	}
 
 	/**
@@ -100,6 +109,7 @@ public static function wpTearDownAfterClass() {
 
 		$registry->unregister( 'tests/hooked-block' );
 		$registry->unregister( 'tests/hooked-block-first-child' );
+		$registry->unregister( 'tests/hooked-block-after-post-content' );
 	}
 
 	/**
@@ -130,6 +140,33 @@ public function test_apply_block_hooks_to_content_from_post_object_respects_igno
 		$this->assertSame( $expected, $actual );
 	}
 
+	/**
+	 * @ticket 63287
+	 */
+	public function test_apply_block_hooks_to_content_from_post_object_does_not_insert_hooked_block_before_container_block() {
+		$filter = function ( $hooked_block_types, $relative_position, $anchor_block_type ) {
+			if ( 'core/post-content' === $anchor_block_type && 'before' === $relative_position ) {
+				$hooked_block_types[] = 'tests/dynamically-hooked-block-before-post-content';
+			}
+
+			return $hooked_block_types;
+		};
+
+		$expected = '<!-- wp:tests/hooked-block-first-child /-->' .
+			self::$post->post_content .
+			'<!-- wp:tests/hooked-block /-->';
+
+		add_filter( 'hooked_block_types', $filter, 10, 3 );
+		$actual = apply_block_hooks_to_content_from_post_object(
+			self::$post->post_content,
+			self::$post,
+			'insert_hooked_blocks'
+		);
+		remove_filter( 'hooked_block_types', $filter, 10 );
+
+		$this->assertSame( $expected, $actual );
+	}
+
 	/**
 	 * @ticket 62716
 	 */