Add samples and bump version to 0.3.0 with compositional shrinker

Author: Nicolás Andrés Gallinal

CHANGELOG.md

@@ -1,3 +1,8 @@
+# v0.3.0 (2019-06-04)
+
+  * Implement compositiona shrinker
+  * Add more examples on how to use it
+
 # v0.2.3 (2019-05-09)
 
   * Fix issue #4

README.md

@@ -16,10 +16,20 @@ Describe properties of your predicates and let `library(quickheck)` generate tes
         reverse(L, R),
         reverse(R, L).
 
+    prop_silly_list(L:list(integer)) :-
+        length(L, Len),
+        Len =:= 3.  % nonsense!
+
     ?- quickcheck(prop_reverse_twice/1).
     100 tests OK
     true.
 
+    ?- quickcheck(prop_silly_list/1).
+    Shrinking to depth 1
+    Failed test prop_silly_list([]:list(integer))
+    false.
+
+
 ## Installation
 
 To install as a package:

examples/composite.pl

@@ -0,0 +1,52 @@
+:- use_module(library(quickcheck)).
+% this is the way of creating new arbitraries
+% defining a composite that will receive a list of primary arbitraries.
+:- multifile quickcheck:composite/3.
+quickcheck:composite(tuple(integer, string), [I:integer, S:string], X) :-
+  X = (I,S).
+
+% composites can also be defined using a single arbitrary 
+% without need to passing a list
+quickcheck:composite(even, I:integer, X) :-
+  X is 2 * I.
+
+quickcheck:composite(odd, I:integer, X) :-
+  X is 2 * I + 1.
+
+% once we define a composite, we may need to define
+% a has_type/2 in case we are going to make use of 
+% the predicate is_of_type(+Composite, @Term).
+% in the case where the composite body is 'invertible' 
+% (ie: tuple(integer, string)) there is no need to
+% because quickcheck will run it 'backwards'
+% but in cases such as odd where the body is not 'invertible'
+% (meaning I cannot be a variable, so it can be run 'backwards')
+% a custom definition must be given.
+:- multifile quickcheck:has_type/2.
+quickcheck:has_type(odd, X) :-
+  integer(X),
+  1 is X mod 2.
+
+prop_tuple(T:tuple(integer, string)) :-
+  T = (_, S),
+  string_length(S, L),
+  L < 4.
+
+prop_odd_plus_even(O:odd, E:even) :-
+  Sum is O + E,
+  is_of_type(odd, Sum),
+  Sum < 4.
+
+:- begin_tests(composite).
+
+test('nonsense, tuples cannot have large string', [forall(between(1, 10, _))]) :-
+  catch(quickcheck(prop_tuple/1), error(counter_example, [(_, String):tuple(integer, string)]), true),
+  string_length(String, Len),
+  Len >= 4.
+
+test('even numbers plus odd numbers gives odd', [forall(between(1, 10, _))]) :-
+  catch(quickcheck(prop_odd_plus_even/2), error(counter_example, [O:odd, E:even]), true),
+  S is O + E,
+  S >= 4.
+
+:- end_tests(composite).

examples/plunit.pl

@@ -0,0 +1,19 @@
+:- use_module(library(quickcheck)).
+
+prop_reverse_twice(L:list) :-
+    reverse(L, R),
+    reverse(R, L).
+
+prop_silly_list(L:list(integer)) :-
+    length(L, Len),
+    Len =:= 3.  % nonsense!
+
+:- begin_tests(list).
+
+test('reverse twice') :-
+    quickcheck(prop_reverse_twice/1).
+
+test('silly list', [fail]) :-
+    quickcheck(prop_silly_list/1).
+
+:- end_tests(list).

examples/example.pl examples/tap.pl

@@ -1,8 +1,8 @@
 name(quickcheck).
 title('QuickCheck randomized testing').
 
-version('0.2.3').
-download('https://github.com/nicoabie/quickcheck/archive/v0.2.3.zip').
+version('0.3.0').
+download('https://github.com/nicoabie/quickcheck/archive/v0.3.0.zip').
 
 author('Michael Hendricks','[email protected]').
 packager('Nico Gallinal','[email protected]').