diff --git a/tests/phpunit/includes/functions.php b/tests/phpunit/includes/functions.php
index 696741166e..17bc879ec1 100644
--- a/tests/phpunit/includes/functions.php
+++ b/tests/phpunit/includes/functions.php
@@ -16,7 +16,15 @@ function tests_reset__SERVER() {
 	unset( $_SERVER['HTTPS'] );
 }
 
-// For adding hooks before loading WP
+/**
+ * Adds hooks before loading WP.
+ *
+ * @param string       $tag             The name for the filter to add.
+ * @param object|array $function_to_add The function/callback to execute on call.
+ * @param int          $priority        The priority.
+ * @param int          $accepted_args   The amount of accepted arguments.
+ * @return bool Always true.
+ */
 function tests_add_filter( $tag, $function_to_add, $priority = 10, $accepted_args = 1 ) {
 	global $wp_filter;
 
@@ -32,13 +40,21 @@ function tests_add_filter( $tag, $function_to_add, $priority = 10, $accepted_arg
 	return true;
 }
 
+/**
+ * Generates a unique function ID based on the given arguments.
+ *
+ * @param string       $tag      Unused. The name of the filter to build ID for.
+ * @param object|array $function The function to generate ID for.
+ * @param int          $priority Unused. The priority.
+ * @return string Unique function ID.
+ */
 function _test_filter_build_unique_id( $tag, $function, $priority ) {
 	if ( is_string( $function ) ) {
 		return $function;
 	}
 
 	if ( is_object( $function ) ) {
-		// Closures are currently implemented as objects
+		// Closures are currently implemented as objects.
 		$function = array( $function, '' );
 	} else {
 		$function = (array) $function;
@@ -47,11 +63,14 @@ function _test_filter_build_unique_id( $tag, $function, $priority ) {
 	if ( is_object( $function[0] ) ) {
 		return spl_object_hash( $function[0] ) . $function[1];
 	} elseif ( is_string( $function[0] ) ) {
-		// Static Calling
+		// Static Calling.
 		return $function[0] . $function[1];
 	}
 }
 
+/**
+ * Deletes all data from the database.
+ */
 function _delete_all_data() {
 	global $wpdb;
 
@@ -79,6 +98,9 @@ function _delete_all_data() {
 	$wpdb->query( "DELETE FROM {$wpdb->usermeta} WHERE user_id != 1" );
 }
 
+/**
+ * Deletes all posts from the database.
+ */
 function _delete_all_posts() {
 	global $wpdb;