Add generic has_blocks function

Merges `gutenberg_post_has_blocks()` and `gutenberg_content_has_blocks()`, resulting in a template function that can be used context-independently.
It accepts a content string, a post object, or post ID, and default to the current post if none of those are given. Make this part of the API behave close to existing WordPress template functions.

It's my first Gutenberg PR, so I'd love to get feedback on this, especially around a better phpunit setup potentially?

See #4418.

lib/blocks.php

@@ -57,7 +57,7 @@ function gutenberg_parse_blocks( $content ) {
 	 * If there are no blocks in the content, return a single block, rather
 	 * than wasting time trying to parse the string.
 	 */
-	if ( ! gutenberg_content_has_blocks( $content ) ) {
+	if ( ! has_blocks( $content ) ) {
 		return array(
 			array(
 				'attrs'     => array(),

lib/compat.php

@@ -140,7 +140,7 @@ function gutenberg_add_rest_nonce_to_heartbeat_response_headers( $response ) {
  * @return string          Paragraph-converted text if non-block content.
  */
 function gutenberg_wpautop( $content ) {
-	if ( gutenberg_content_has_blocks( $content ) ) {
+	if ( has_blocks( $content ) ) {
 		return $content;
 	}
 

lib/plugin-compat.php

@@ -26,7 +26,7 @@
  * @return array $post      Post object.
  */
 function gutenberg_remove_wpcom_markdown_support( $post ) {
-	if ( class_exists( 'WPCom_Markdown' ) && gutenberg_content_has_blocks( $post['post_content'] ) ) {
+	if ( class_exists( 'WPCom_Markdown' ) && has_blocks( $post['post_content'] ) ) {
 		WPCom_Markdown::get_instance()->unload_markdown_for_posts();
 	}
 	return $post;

lib/register.php

@@ -318,6 +318,30 @@ function gutenberg_can_edit_post_type( $post_type ) {
 	return apply_filters( 'gutenberg_can_edit_post_type', $can_edit, $post_type );
 }
 
+/**
+ * Determine whether a post or content string has blocks.
+ *
+ * This test optimizes for performance rather than strict accuracy, detecting
+ * the pattern of a block but not validating its structure. For strict accuracy
+ * you should use the block parser on post content.
+ *
+ * @since 3.4.0
+ * @see gutenberg_parse_blocks()
+ *
+ * @param int|string|WP_Post|null $post Optional. Post content, post ID, or post object. Defaults to global $post.
+ * @return bool Whether the post has blocks.
+ */
+function has_blocks( $post = null ) {
+	if ( ! is_string( $post ) ) {
+		$wp_post = get_post( $post );
+		if ( $wp_post instanceof WP_Post ) {
+			$post = $wp_post->post_content;
+		}
+	}
+
+	return false !== strpos( (string) $post, '<!-- wp:' );
+}
+
 /**
  * Determine whether a post has blocks. This test optimizes for performance
  * rather than strict accuracy, detecting the pattern of a block but not
@@ -327,13 +351,14 @@ function gutenberg_can_edit_post_type( $post_type ) {
  * @see gutenberg_parse_blocks()
  *
  * @since 0.5.0
+ * @deprecated 3.4.0 Use has_block()
  *
  * @param object $post Post.
  * @return bool  Whether the post has blocks.
  */
 function gutenberg_post_has_blocks( $post ) {
-	$post = get_post( $post );
-	return $post && gutenberg_content_has_blocks( $post->post_content );
+	_deprecated_function( __FUNCTION__, '3.4.0', 'has_blocks()' );
+	return has_blocks( $post );
 }
 
 /**
@@ -342,14 +367,17 @@ function gutenberg_post_has_blocks( $post ) {
  * but not validating its structure. For strict accuracy, you should use the
  * block parser on post content.
  *
- * @since 1.6.0
  * @see gutenberg_parse_blocks()
  *
+ * @since 1.6.0
+ * @deprecated 3.4.0 Use has_block()
+ *
  * @param string $content Content to test.
  * @return bool Whether the content contains blocks.
  */
 function gutenberg_content_has_blocks( $content ) {
-	return false !== strpos( $content, '<!-- wp:' );
+	_deprecated_function( __FUNCTION__, '3.4.0', 'has_blocks()' );
+	return has_blocks( $content );
 }
 
 /**
@@ -364,7 +392,7 @@ function gutenberg_content_has_blocks( $content ) {
  * @return int The block format version.
  */
 function gutenberg_content_block_version( $content ) {
-	return gutenberg_content_has_blocks( $content ) ? 1 : 0;
+	return has_blocks( $content ) ? 1 : 0;
 }
 
 /**
@@ -375,7 +403,7 @@ function gutenberg_content_block_version( $content ) {
  * @return array                A filtered array of post display states.
  */
 function gutenberg_add_gutenberg_post_state( $post_states, $post ) {
-	if ( gutenberg_post_has_blocks( $post ) ) {
+	if ( has_blocks( $post ) ) {
 		$post_states[] = 'Gutenberg';
 	}
 

phpunit/class-registration-test.php

@@ -10,6 +10,19 @@
  */
 class Registration_Test extends WP_UnitTestCase {
 
+	protected static $post_id;
+
+	public static function wpSetUpBeforeClass( $factory ) {
+		self::$post_id = $factory->post->create( array(
+			'post_content' => file_get_contents( dirname( __FILE__ ) . '/fixtures/do-blocks-original.html' ),
+		) );
+	}
+
+	public static function wpTearDownAfterClass() {
+		// Also deletes revisions.
+		wp_delete_post( self::$post_id, true );
+	}
+
 	function render_stub() {}
 
 	function tearDown() {
@@ -60,4 +73,25 @@ function test_get_dynamic_block_names() {
 		$this->assertContains( 'core/dynamic', $dynamic_block_names );
 		$this->assertNotContains( 'core/dummy', $dynamic_block_names );
 	}
+
+	function test_has_blocks() {
+		// Test with passing post ID.
+		$this->assertTrue( has_blocks( self::$post_id ) );
+
+		// Test with passing WP_Post object.
+		$this->assertTrue( has_blocks( get_post( self::$post_id ) ) );
+
+		// Test with passing content string.
+		$this->assertTrue( has_blocks( get_post( self::$post_id ) ) );
+
+		// Test default.
+		$this->assertFalse( has_blocks() );
+		$query = new WP_Query( array( 'post__in' => array( self::$post_id ) ) );
+		$query->the_post();
+		$this->assertTrue( has_blocks() );
+
+		// Test string (without blocks).
+		$content = file_get_contents( dirname( __FILE__ ) . '/fixtures/do-blocks-expected.html' );
+		$this->assertFalse( has_blocks( $content ) );
+	}
 }