Q:

Reload components list

Here is my workflow: I have a running REPL in my emacs and I create a new system. When I try to test the system with (asdf:test-system :system) I get a Component :SYSTEM not found error. Of course when I restart the lisp image the component is found.
My question is: Can I signal to ASDF that there is a new system in the ~/common-lisp/ directory?
I imagine the command I am looking for would be something like: (asdf:reload-systems)

A:

Clearing the configuration works when loading systems. Hopefully this also works for testing them:
* (asdf:load-system :test)

debugger invoked on a ASDF/FIND-SYSTEM:MISSING-COMPONENT in thread
#<THREAD "main thread" RUNNING {1001E0E533}>:
  Component :TEST not found

Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [RETRY                        ] Retry ASDF operation.
  1: [CLEAR-CONFIGURATION-AND-RETRY] Retry ASDF operation after resetting the
                                     configuration.
  2: [ABORT                        ] Exit debugger, returning to top level.

((:METHOD ASDF/OPERATE:OPERATE (SYMBOL T)) ASDF/LISP-ACTION:LOAD-OP :TEST) [fast-method]
0] 

Using restart #1 makes it work here. But you can also do it yourself:
* (asdf:clear-configuration)

NIL
* (asdf:load-system :test)

T
* 

Note that the ~/common-lisp/ path is supported by default only from ASDF 3.1.2, you might need to check which version is yours.
For details see the documentation.

