There shouldn't be anything particularly complex in test code, limiting the extent of any "reimplementation". Moreover, if the test client is different from rea

There shouldn't be anything particularly complex in test code, limiting the extent of any "reimplementation". Moreover, if the test client is different from real clients and not "in sync" it's a good thing: unit tests that do something differently within the limits of documented acceptable behaviour expose assumptions and bugs. For example, suppose outputs should be sorted in a certain way, but they are sorted if a client presents sorted inputs and not because they are actually checked and sorted: a test with random inputs can expose the hole.