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Fixed error messages, added tests for type errors.

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This commit is contained in:
Stephen Bloch 2011-10-02 22:54:34 -04:00
parent 3bfce02bd6
commit 753dfa3cb2
2 changed files with 59 additions and 6 deletions
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28
collects/picturing-programs/private/tiles.rkt
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@ -81,18 +81,28 @@
(rotate 45 (flip-vertical (rotate -45 picture))))
; synonyms
(define (flip-main picture) (reflect-main-diag picture))
(define (flip-other picture) (reflect-other-diag picture))
(define (flip-main picture)
(check-image 'flip-main picture "first")
(reflect-main-diag picture))
(define (flip-other picture)
(check-image 'flip-other picture "first")
(reflect-other-diag picture))
; natural-number? anything -> boolean
(define (natural-number? x)
(and (integer? x) (>= x 0)))
; natural-bounded? natural anything -> boolean
(define (natural-bounded? max x)
(and (natural-number? x) (<= x max)))
; crop-left : image natural-number -> image
; deletes that many pixels from left edge of image
(define (crop-left picture pixels)
(check-image 'crop-left picture "first")
(check-arg 'crop-left (natural-number? pixels) "natural number" "second" pixels)
(check-arg 'crop-left (natural-bounded? (image-width picture) pixels)
(format "natural number <= ~a" (image-width picture))
"second" pixels)
(crop pixels 0
(- (image-width picture) pixels) (image-height picture)
picture))
@ -101,7 +111,9 @@
; deletes that many pixels from top edge of image
(define (crop-top picture pixels)
(check-image 'crop-top picture "first")
(check-arg 'crop-top (natural-number? pixels) "natural number" "second" pixels)
(check-arg 'crop-top (natural-bounded? (image-height picture) pixels)
(format "natural number <= ~a" (image-height picture))
"second" pixels)
(crop 0 pixels
(image-width picture) (- (image-height picture) pixels)
picture))
@ -110,7 +122,9 @@
; deletes that many pixels from right edge of image
(define (crop-right picture pixels)
(check-image 'crop-right picture "first")
(check-arg 'crop-right (natural-number? pixels) "natural number" "second" pixels)
(check-arg 'crop-right (natural-bounded? (image-width picture) pixels)
(format "natural number <= ~a" (image-width picture))
"second" pixels)
(crop 0 0
(- (image-width picture) pixels)
(image-height picture)
@ -120,7 +134,9 @@
; deletes that many pixels from bottom edge of image
(define (crop-bottom picture pixels)
(check-image 'crop-bottom picture "first")
(check-arg 'crop-bottom (natural-number? pixels) "natural number" "second" pixels)
(check-arg 'crop-bottom (natural-bounded? (image-height picture) pixels)
(format "natural number <= ~a" (image-height picture))
"second" pixels)
(crop 0 0
(image-width picture)
(- (image-height picture) pixels)

37
collects/picturing-programs/tests/tiles-error-tests.rkt Normal file
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@ -0,0 +1,37 @@
;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname tiles-error-tests) (read-case-sensitive #t) (teachpacks ()) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ())))
(require picturing-programs)
(check-error (reflect-horiz 17)
"reflect-horiz: expected <image> as first argument, given: 17")
(check-error (reflect-vert "hello")
"reflect-vert: expected <image> as first argument, given: \"hello\"")
(check-error (reflect-main-diag true)
"reflect-main-diag: expected <image> as first argument, given: true")
(check-error (reflect-other-diag false)
"reflect-other-diag: expected <image> as first argument, given: false")
(check-error (flip-main 'blue)
"flip-main: expected <image> as first argument, given: 'blue")
(check-error (flip-other "snark")
"flip-other: expected <image> as first argument, given: \"snark\"")
(check-error (crop-left pic:hacker 50)
"crop-left: expected <natural number <= 48> as second argument, given: 50")
(check-error (crop-right pic:bloch 100)
"crop-right: expected <natural number <= 93> as second argument, given: 100")
(check-error (crop-top pic:book 56)
"crop-top: expected <natural number <= 39> as second argument, given: 56")
(check-error (crop-bottom pic:hacker 56)
"crop-bottom: expected <natural number <= 48> as second argument, given: 56")
(check-error (crop-left pic:hacker -3)
"crop-left: expected <natural number <= 48> as second argument, given: -3")
(check-error (crop-top pic:book 3.2)
"crop-top: expected <natural number <= 39> as second argument, given: 3.2")
(check-error (crop-bottom pic:book pic:book)
"crop-bottom: expected <natural number <= 39> as second argument, given: #<image>")
(check-error (rotate-cw 17)
"rotate-cw: expected <image> as first argument, given: 17")
(check-error (rotate-ccw true)
"rotate-ccw: expected <image> as first argument, given: true")
(check-error (rotate-180 "goodbye")
"rotate-180: expected <image> as first argument, given: \"goodbye\"")