I assume that “not wanting to write tests” is when the tests are more complex than the code tested, for example writing tests for a GUI application using a clos

I assume that “not wanting to write tests” is when the tests are more complex than the code tested, for example writing tests for a GUI application using a closed-source platform framework is complex (if at all possible). You can write tests for the core algorithms and data structures but that is often only around 10%.