extensions should be an empty array if extensions are not supported

Author: kares

test/db/postgres/simple_test.rb

@@ -143,7 +143,7 @@ def test_extensions
       assert connection.extension_enabled?('plpgsql')
       assert ! connection.extension_enabled?('invalid')
     else
-      assert ! connection.extensions
+      assert_empty connection.extensions
     end
   end