From 753dfa3cb286706fb14d3857d7ef116c189cc707 Mon Sep 17 00:00:00 2001
From: Stephen Bloch <sbloch@adelphi.edu>
Date: Sun, 2 Oct 2011 22:54:34 -0400
Subject: [PATCH] Fixed error messages, added tests for type errors.

---
 collects/picturing-programs/private/tiles.rkt | 28 +++++++++++---
 .../tests/tiles-error-tests.rkt               | 37 +++++++++++++++++++
 2 files changed, 59 insertions(+), 6 deletions(-)
 create mode 100644 collects/picturing-programs/tests/tiles-error-tests.rkt

diff --git a/collects/picturing-programs/private/tiles.rkt b/collects/picturing-programs/private/tiles.rkt
index 281d554d2c..b858db49e1 100644
--- a/collects/picturing-programs/private/tiles.rkt
+++ b/collects/picturing-programs/private/tiles.rkt
@@ -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)
diff --git a/collects/picturing-programs/tests/tiles-error-tests.rkt b/collects/picturing-programs/tests/tiles-error-tests.rkt
new file mode 100644
index 0000000000..ffcb0464ec
--- /dev/null
+++ b/collects/picturing-programs/tests/tiles-error-tests.rkt
@@ -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\"")
\ No newline at end of file