No, You've plenty: we run our climate models on other planets, too. There are operational models running for Mars (to predict dust storms);
Titan, Jupiter, Saturn, Venus, Neptune and Uranus have been tested too.
We also have paleoclimates, matching CO2 and temperature patterns against fossil and isotopic records both on Earth and recently on Mars.
We have lots of individual tests: climate model accuracy on a regional scale, when the models are not tuned to this; getting predictions
such as Arctic ampliification right, etc. Getting the magnitude and duration of global cooling in the wake of volcanos such as Pinatubo, etc.
As another poster said, we've plenty of tests that we can do and have done, if you show any imagination.