;;
;; FILE:     rackunit-example.rkt
;; AUTHOR:   Eugene Wallingford
;; UPDATED:  2011/02/02
;; COMMENT:  A program that uses the rackunit module to define
;;           unit tests for function.
;;

#lang racket

; -- The following expression says that this file requires
; -- functions exported by the rackunit module.  The name
; -- "rackunit" is not quoted like a string, which indicates
; -- that is in Racket's standard path.  require is similar
; -- to "import" in Python and Java.

(require rackunit)

; -- The rest of the file is like any other program file, except
; -- that it can use names exported by the file that we required.
; -- Here, I define a simple function.

(define square
  (lambda (n)
    (* n n)))

; -- Among the functions that the rackunit module provides is
; -- check-equal?, which compares the result of an evaluation
; -- to an expected value.  We can use it to check whether
; -- our function behaves as expected.

(check-equal? (square 1)  1)
(check-equal? (square 7) 49)
(check-equal? (square 9) 81)

; -- We can use rackunit to define automated tests for the
; -- functions we write.  We will use rackunit tests for most
; -- of our code and homework assignments this semester.