chickadee » missbehave » matcher

(matcher (check (subject) check-code) (message (form subject negate) message-code))syntax

This creates a fresh matcher object. You need to implement both the check and the message.

  • check The check is a procedure that receives one argument, the subject. The subject is a promise so you need to force it if you want to retrieve the value.
  • message This is the procedure that is invoked to generate the message. It receives three arguments
    • form This is the quoted form that was passed to expect
    • subject This is the subject. Again this is a promise so you need to force it to retrieve the actual value.
    • negate Indicates if the check shall be negated. This is set to true if the expect-form has been wrapped into a (do-not) form.
(define (greater-than x)
   (check (subject)
     (> (force subject) x))
   (message (form subject negate)
     (if negate
        (sprintf "Expected ~A to be less than or equal to ~A" (force subject) x)
        (sprintf "Expected ~A to be greater than ~A" (force subject) x)))))

(expect 10 (be (greater-than 5)))