Index: tests/phpunit/tests/media/getPostGalleries.php
===================================================================
--- tests/phpunit/tests/media/getPostGalleries.php	(revision 56612)
+++ tests/phpunit/tests/media/getPostGalleries.php	(working copy)
@@ -575,7 +575,7 @@
 
 		}
 
-		$ids_joined = join( ',', $ids );
+		$ids_joined = implode( ',', $ids );
 
 		$global_post_id = self::factory()->post->create(
 			array(
@@ -844,8 +844,8 @@
 
 		}
 
-		$ids1_joined = join( ',', array_slice( $ids, 0, 3 ) );
-		$ids2_joined = join( ',', array_slice( $ids, 3, 3 ) );
+		$ids1_joined = implode( ',', array_slice( $ids, 0, 3 ) );
+		$ids2_joined = implode( ',', array_slice( $ids, 3, 3 ) );
 
 		$blob = <<<BLOB
 [gallery ids="$ids1_joined"]
@@ -907,8 +907,8 @@
 
 		}
 
-		$ids1_joined = join( ',', array_slice( $ids, 0, 3 ) );
-		$ids2_joined = join( ',', array_slice( $ids, 3, 3 ) );
+		$ids1_joined = implode( ',', array_slice( $ids, 0, 3 ) );
+		$ids2_joined = implode( ',', array_slice( $ids, 3, 3 ) );
 		$blob        = <<<BLOB
 [gallery ids="$ids1_joined" type="type" foo="bar"]
 
Index: tests/phpunit/tests/media.php
===================================================================
--- tests/phpunit/tests/media.php	(revision 56612)
+++ tests/phpunit/tests/media.php	(working copy)
@@ -552,8 +552,8 @@
 			$ids2_srcs[] = 'http://' . WP_TESTS_DOMAIN . '/wp-content/uploads/' . "image$i.jpg";
 		}
 
-		$ids1_joined = join( ',', array_slice( $ids1, 0, 3 ) );
-		$ids2_joined = join( ',', array_slice( $ids2, 3, 3 ) );
+		$ids1_joined = implode( ',', array_slice( $ids1, 0, 3 ) );
+		$ids2_joined = implode( ',', array_slice( $ids2, 3, 3 ) );
 
 		$blob    = <<<BLOB
 [gallery ids="$ids1_joined"]
@@ -638,8 +638,8 @@
 			$imgs[]     = '<figure><img src="' . $url . '" data-id="' . $i . '" /></figure>';
 		}
 
-		$imgs1_joined = join( "\n", array_slice( $imgs, 0, 3 ) );
-		$imgs2_joined = join( "\n", array_slice( $imgs, 3, 3 ) );
+		$imgs1_joined = implode( "\n", array_slice( $imgs, 0, 3 ) );
+		$imgs2_joined = implode( "\n", array_slice( $imgs, 3, 3 ) );
 
 		$blob    = <<<BLOB
 <!-- wp:gallery -->
@@ -677,8 +677,8 @@
 
 		}
 
-		$ids1_joined = join( ',', array_slice( $ids, 0, 3 ) );
-		$ids2_joined = join( ',', array_slice( $ids, 3, 3 ) );
+		$ids1_joined = implode( ',', array_slice( $ids, 0, 3 ) );
+		$ids2_joined = implode( ',', array_slice( $ids, 3, 3 ) );
 
 		$blob    = <<<BLOB
 <!-- wp:gallery {"ids":[$ids1_joined]} -->
@@ -718,9 +718,9 @@
 			$imgs[]     = '<figure><img src="' . $url . '" data-id="' . $i . '" /></figure>';
 		}
 
-		$ids1_joined  = join( "\n", array_slice( $ids, 0, 3 ) );
-		$ids2_joined  = join( "\n", array_slice( $ids, 3, 3 ) );
-		$imgs2_joined = join( "\n", array_slice( $imgs, 3, 3 ) );
+		$ids1_joined  = implode( "\n", array_slice( $ids, 0, 3 ) );
+		$ids2_joined  = implode( "\n", array_slice( $ids, 3, 3 ) );
+		$imgs2_joined = implode( "\n", array_slice( $imgs, 3, 3 ) );
 
 		$blob    = <<<BLOB
 [gallery ids="$ids1_joined"]
@@ -762,7 +762,7 @@
 
 		}
 
-		$imgs_joined = join( "\n", $imgs );
+		$imgs_joined = implode( "\n", $imgs );
 
 		$blob    = <<<BLOB
 <!-- wp:columns -->
@@ -805,7 +805,7 @@
 
 		}
 
-		$imgs_joined = join( "\n", $imgs );
+		$imgs_joined = implode( "\n", $imgs );
 
 		$blob    = <<<BLOB
 <!-- wp:gallery -->