These tests are not actually checking that response has been populated entirely correctly, response.params is returning whatever the gateway returned (and in this case its your stubbed string).

The code is not currently working, but the test isn't catching it either.

Test should be changed to as follows to catch the bug:

```ruby
    assert_equal "U", response.avs_result["code"]
    assert_equal "S", response.cvv_result["code"]
```

(same for remote test also, and a few other places - please check)