[cultofthecow]

what does it mean “mocked out hashtable”?

Whole hashtable? Or what?

You mock interface/api of “something” you depend on to model the behavior you might deal with within the part of code you test.

thats it. nothing else.

during unit test phase I want to make sure that this exact code works as a state machine given all the possible inputs/outputs and that it handles any possible situation any dependency can cause.

If you need to debug code BECAUSE of the tests and not WITH the tests then something is wrong with the architecture or approach.

tldr. mock dependencies. model behavior of the dependencies. make sure you can debug the code with the help of your unit tests on the very layer you’re working with at the moment.

[sagarm]

I find that mock-heavy tests I've interacted with are low ROI: they don't find or predict bugs, require significant work to write, and often have to be updated when the code under test has changed even when the actual feature/case being tested has not changed.

While mocks can be useful, IMO "never use mocks" isn't a terrible rule of thumb.