https://jakubsobolewski.com/blog/test-doubles-taxonomy/
Test Doubles Taxonomy for R: Dummy, Stub, Spy, Mock, Fake
Jakub Sobolewski
Jun 12, 2026
"Mock the database. Mock the API. Mock the function.... There are five distinct types, each with a specific job. Knowing which is which is how you stop writing tests that do the wrong thing."