I've found this is more and more the primary way I use the Python repl - I invoke pytest and tell it to drop me into the debugger if there's an error.

I usually have a test data set and run my module against it in IPython. So input is automated to some extent. If I'm analyzing the output, it can be helpful to quickly adjust charts and graphs. I'm now in the process of building distribution tests into my test suite, but it's not clear how to track everything. I need data sources essentially kept under version control, but which are generally too big for git.