Testing and debugging language Virtual Machines (VMs) is a laborious task without the proper tooling. This complexity is aggravated when the VM targets multiple architectures. Simulation-based VM generator frameworks allow one to write test cases on the simulation, however they do not ensure the correctness of the generated artifact due to the semantic gap between the environments. In this article we propose Test Transmutation. It extends simulationbased VM generator frameworks to also generate simulation test cases and execute them on the generated VMs. It extends such frameworks to translate test cases and applies differential testing and non-semantic-preserving mutations. Test Transmutation detects bugs that are representative of typical VM modifications. Moreover, we apply it to a set of real test cases of the Pharo VM and find several issues. Our approach shows promising results to test simulation-based VM generator frameworks.