Erlang Code Evolution Control

In the software lifecycle, a program can evolve several times for different reasons such as the optimisation of a bottle-neck, the refactoring of an obscure function, etc. These code changes often involve several functions or modules, so it can be difficult to know whether the correct behaviour of the previous releases has been preserved in the new release. Most developers rely on a previously defined test suite to check this behaviour preservation. We propose here an alternative approach to automatically obtain a test suite that specifically focusses on comparing the old and new versions of the code. Our test case generation is directed by: a sophisticated combination of several already existing tools such as TypEr, CutEr, and PropEr; the choice of an expression of interest whose behaviour must be preserved; and the recording of the sequences of values this expression is evaluated to. All the presented work has been implemented in an open-source tool that is publicly available on GitHub.