define-test (name &body body)

name -- a symbol
body -- the forms to be evaluated

This macro defines a test called name with the expressions specified in body, in the package specified by the value of *package* in effect when define-test is executed.

The expresssions are assembled into runnable code whenever needed by run-tests or run-all-tests. Hence you can define or redefine macros without reloading tests using those macros.