Add failing puzzle test.

1 files changed, 4 insertions, 1 deletions

diff --git a/8puzzle/PuzzleTest.hs b/8puzzle/PuzzleTest.hs
index cbd88af..0044608 100644
--- a/8puzzle/PuzzleTest.hs
+++ b/8puzzle/PuzzleTest.hs
@@ -10,13 +10,14 @@ import Puzzle hiding (main)
 
 instance Arbitrary Puzzle where
     arbitrary = do
-      size <- choose (1, 10)
+      size <- choose (2, 4)
       board <- shuffle [0 .. (size*size - 1)]
       return $ Puzzle size (V.fromList board) False
 
 tests = [
   testGroup "Board"
     [ testProperty "neighbors have distance of 1" prop_neighborDistance,
+      testProperty "can solve puzzle" prop_canSolvePuzzle,
       testCase "basic distance" test_distance
     ]
   ]
@@ -27,6 +28,8 @@ test_distance = distance puzzle @?= 4
 prop_neighborDistance p = all validNeighbor (neighbors p)
     where validNeighbor n = abs (distance p - distance n) == 1
 
+prop_canSolvePuzzle = not . null . solve
+
 example = Puzzle 2 (V.fromList [1, 3, 2, 0]) False
 
 main = do