(plan 5)

(expect "unless - true condition"
        (null (unless t 'fail)))

(expect "unless - false condition"
        (equal 'ok (unless nil 'ok)))

(let ((a 'ok))
  (unless t (set a 'fail))
  (expect "unless - does not evaluate on true" (equal a 'ok)))

(expect "unless - without body returns nil"
        (null (unless nil)))

(expect "when - implicit progn"
        (equal 'ok (unless nil 'wrong 'wrong2 'ok)))