Improving code readability

tests/TestCase/Database/Schema/PostgresSchemaTest.php

@@ -1129,12 +1129,12 @@ SQL;
         $mock->expects($this->any())
             ->method('quote')
             ->will($this->returnCallback(function ($value) {
-                return '\'' . $value . '\'';
+                return "'$value'";
             }));
         $mock->expects($this->any())
             ->method('quoteIdentifier')
             ->will($this->returnCallback(function ($value) {
-                return '"' . $value . '"';
+                return "'$value'";
             }));
         $driver->connection($mock);
         return $driver;