This is more of an english language question - we have various types of tests - unit tests, A/B tests, etc...

Suppose I need to migrate code to a different language, machine, or any other different environment specification, with the definition that it reproduces the original application exactly (bugs included!). I am looking for a name for such a test.

Currently I am using functional testing, but I feel that's to general and am looking for something better. It is also somewhat misleading since the "function" is not the implemented algorithm but reproducing behavior of another application.