I know a lot of people in Lisp and Smalltalk communities that use unit tests still use the interactive debugging environment. In fact, many of them write their unit tests in the REPL, and then paste them into their test-code. There are even a couple of unit testing libraries for CL that are specifically designed for doing this.

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I also recommend that you watch the video xuejie posted (https://www.youtube.com/watch?v=4hfMUP5iTq8), as it's about using a debugger to write code more than using a debugger to fix code.