Print a random failing test for incorrect solution

1 files changed, 17 insertions, 0 deletions

diff --git a/prolog/engine.py b/prolog/engine.py
index e64f728..be19fec 100644
--- a/prolog/engine.py
+++ b/prolog/engine.py
@@ -127,6 +127,23 @@ def test(name, code):
     except Exception as ex:
         return False
 
+# Try to generate a random test case for problem [name] with [solution] that
+# fails for [code]. Give up after [tries] attempts.
+def create_failing_test(name, solution, code, tries=20):
+    try:
+        for i in range(tries):
+            reply = create_and_ask(code=solution,
+                                   query='create_test({}, Test)'.format(name))
+            testcase = reply['data'][0]['Test']
+            reply = create_and_ask(code=code,
+                                   query='run_test({}, Result)'.format(testcase))
+            result = reply['data'][0]['Result']
+            if not result.startswith('success'):
+                return testcase
+    except Exception as ex:
+        pass
+    return None
+
 # Basic sanity check.
 if __name__ == '__main__':
     engine = create(code='dup([],[]). dup([H|T],[H,H|TT]) :- dup(T,TT).')