How to use Test Stubs with Minitest Discussion

would it be reasonable to have a subset of the testsuite only testing expensive external dependencies (db access, 3rd/party/integrations, etc. and run these on the side, and have stubbed methods being tested on a second threat, so to speak, that could run continuously (via guard, i.e.) during development? i guess one would still need some sort of integration test on top of that to make sure there is no disconnect between the two parts...