From 3b30cce99849246868421294a6b9637b987e43b2 Mon Sep 17 00:00:00 2001
From: Jack Firth <jackhfirth@gmail.com>
Date: Sat, 11 Jul 2015 21:53:32 -0700
Subject: [PATCH 1/3] Add test-lens module

---
 lens/test-util/test-lens.rkt | 45 ++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 lens/test-util/test-lens.rkt

diff --git a/lens/test-util/test-lens.rkt b/lens/test-util/test-lens.rkt
new file mode 100644
index 0000000..02ba2f1
--- /dev/null
+++ b/lens/test-util/test-lens.rkt
@@ -0,0 +1,45 @@
+#lang racket
+
+(require rackunit
+         fancy-app
+         "../main.rkt")
+
+(provide
+ (contract-out
+  [check-view (-> lens? any/c any/c void?)]
+  [check-set (-> lens? any/c any/c any/c void?)]
+  [check-view-set (-> lens? any/c void?)]
+  [check-set-view (-> lens? any/c any/c void?)]
+  [check-set-set (-> lens? any/c any/c any/c void?)]
+  [test-lens-laws (-> lens? any/c any/c any/c void?)]))
+
+
+(define-check (check-view lens target expected-view)
+  (check-equal? (lens-view lens target) expected-view))
+
+(define-check (check-set lens target new-view expected-new-target)
+  (check-equal? (lens-set lens target new-view) expected-new-target))
+
+
+(define-check (check-view-set lens target)
+  (check-equal? (lens-set lens target (lens-view lens target))
+                target
+                "setting target's view to its own view not equal? to itself"))
+
+(define-check (check-set-view lens target new-view)
+  (check-equal? (lens-view lens (lens-set lens target new-view))
+                new-view
+                "view of target after setting it's view not equal? to the set view"))
+
+(define-check (check-set-set lens target new-view1 new-view2)
+  (let* ([target* (lens-set lens target new-view1)]
+         [target** (lens-set lens target* new-view2)])
+    (check-equal? (lens-view lens target**)
+                  new-view2
+                  "view of target after setting it's view twice not equal? to second view")))
+
+(define (test-lens-laws lens test-target test-view1 test-view2)
+  (check-view-set lens test-target)
+  (check-set-view lens test-target test-view1)
+  (check-set-view lens test-target test-view2)
+  (check-set-set lens test-target test-view1 test-view2))

From ece0554d23c6e742db704f822645f765882aa8da Mon Sep 17 00:00:00 2001
From: Jack Firth <jackhfirth@gmail.com>
Date: Sat, 11 Jul 2015 22:02:34 -0700
Subject: [PATCH 2/3] Remove cyclic dependencies for lens testing

---
 lens/test-util/test-lens.rkt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lens/test-util/test-lens.rkt b/lens/test-util/test-lens.rkt
index 02ba2f1..def9054 100644
--- a/lens/test-util/test-lens.rkt
+++ b/lens/test-util/test-lens.rkt
@@ -2,7 +2,8 @@
 
 (require rackunit
          fancy-app
-         "../main.rkt")
+         "../base/base.rkt"
+         "../base/view-set.rkt")
 
 (provide
  (contract-out

From 5b5955f732890eacd1955f94b08dd3ac07c0ba18 Mon Sep 17 00:00:00 2001
From: Jack Firth <jackhfirth@gmail.com>
Date: Sat, 11 Jul 2015 22:02:49 -0700
Subject: [PATCH 3/3] Add example use of lens law testing

---
 lens/list/car-cdr.rkt | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/lens/list/car-cdr.rkt b/lens/list/car-cdr.rkt
index 4016316..3a17bca 100644
--- a/lens/list/car-cdr.rkt
+++ b/lens/list/car-cdr.rkt
@@ -7,7 +7,8 @@
 (require "../base/main.rkt")
 
 (module+ test
-  (require rackunit))
+  (require rackunit
+           "../test-util/test-lens.rkt"))
 
 
 (define (set-car pair v)
@@ -20,5 +21,10 @@
 (define cdr-lens (make-lens cdr set-cdr))
 
 (module+ test
-  (check-equal? (lens-view car-lens '(1 . 2)) 1)
-  (check-equal? (lens-view cdr-lens '(1 . 2)) 2))
+  (check-view car-lens '(1 . 2) 1)
+  (check-set car-lens '(1 . 2) 'a '(a . 2))
+  (test-lens-laws car-lens '(1 . 2) 'a 'b)
+
+  (check-view cdr-lens '(1 . 2) 2)
+  (check-set cdr-lens '(1 . 2) 'a '(1 . a))
+  (test-lens-laws cdr-lens '(1 . 2) 'a 'b))