I don't like the .Never(). It implies that the `AssertValidBranchName` call is a side-effect that should never happen. I would do one of these: 

1. Remove the line.
2. `gitRepository.Stub(x => x.AssertValidBranchName(GIT_BRANCH_TO_INIT)).Return(GIT_BRANCH_TO_INIT);` (this way all the tests can be the same.