Even without the continuation piece, it has always puzzled me why the test frameworks that I've used (mostly pytest and catch) don't explicitly model dependencies between layers. Especially in a system where layers have been carefully levelized. Assuming for the sake of example that there are no mocks involved, if subsystem B depends on subsystem A (say A is some global utility classes), then I would want all of A's unit tests to pass before running any of subsystem B's tests. Not sure why this is absent, or perhaps I'm using the wrong test systems.