;; file:    test-setup.rkt
;; author:  Robert Keller
;; purpose: illustrating unit tests

#lang racket

(require htdp/testing) ; incant to get check-expect, check-within, generate-report

; The format for check-expect is (check-expect <expression> <desired answer>)

(check-expect (+ 2 2) 4) ;; ok
(check-expect (+ 2 3) 6) ;; should fail intentionally

; (check-expect (+ 1 .5) 1.5) ;; Not allowed because .5 is "inexact" due to floating pt.

; The format for check-within is (check-within <expression> <desired answer> <tolerance>)

(check-within (+ 1 .5)    1.5   0)    ;; ok
(check-within (+ 1/3 0.5) 0.833 0)    ;; should fail because of no tolerance
(check-within (+ 1/3 0.5) 0.833 1e-4) ;; should fail because of too little tolerance
(check-within (+ 1/3 0.5) 0.833 1e-3) ;; ok

(generate-report)

;Output (I added line breaks between cases.):
;
;Ran 6 checks.
;3 of the 6 checks failed.
;
;	Actual value 5 differs from 6, the expected value.
; In test-setup.rkt at line 6 column 0
;
;	Actual value 0.8333333333333333 is not within 0 of expected value 0.833.
; In test-setup.rkt at line 11 column 0
;
;	Actual value 0.8333333333333333 is not within 0.0001 of expected value 0.833.
; In test-setup.rkt at line 12 column 0