diff --git a/phpunit/block-supports/shadow-test.php b/phpunit/block-supports/shadow-test.php
index bc0c1964e26951..c2fc0defe8199c 100644
--- a/phpunit/block-supports/shadow-test.php
+++ b/phpunit/block-supports/shadow-test.php
@@ -70,6 +70,11 @@ public function test_gutenberg_apply_shadow_support( $support, $value, $expected
 		$this->assertSame( $expected, $actual );
 	}
 
+	/**
+	 * Data provider.
+	 *
+	 * @return array
+	 */
 	public function data_generate_shadow_fixtures() {
 		return array(
 			'with no styles'               => array(