I knew it was possible, but I got to try it recently.

Here I run a test with fiveam. It fails. I tell fiveam to enter the debugger on failures with

(setf 5am:*on-error* :debug)

so we have an immediate feedback and we can re-run the test from where it left off by choosing the appropriate restart.

Other test frameworks like Parachute allow that.

This is one of the things that make development in Common Lisp enjoyable and faster than with other workflows. Also, it’s built-in, there is no fancy editor plugin or configuration.

In the debugger:

  • <enter> on a backtrace shows more of it
  • v on a backtrace goes to the corresponding line or function.
  • more options with the menu.