diff --git a/genstar/Test.hs b/genstar/Test.hs index ffa8f8f..9eca71e 100644 --- a/genstar/Test.hs +++ b/genstar/Test.hs @@ -2,13 +2,25 @@ module Test where -import Main (Vertex (Point), fromAngle, move, scale, vertexDistance) -import Test.QuickCheck (discard, quickCheck, quickCheckAll) +import Data.List (partition) +import Main (PolygonPath (PolygonPath), Vertex (Point), fromAngle, move, regularPolygon, scale, star, vertexDistance) +import Test.QuickCheck (Arbitrary (arbitrary), Positive, chooseInteger, discard, getPositive, quickCheck, quickCheckAll) + +newtype PolygonVertexCount a = PolygonVertexCount a deriving (Show) + +instance Integral a => Arbitrary (PolygonVertexCount a) where + arbitrary = do + x <- chooseInteger (3, 1000) + return $ PolygonVertexCount (fromIntegral x) -- | the largest acceptable difference between two doubles so they are considered equal epsilon :: Double epsilon = 1e-10 +getVertices :: Maybe PolygonPath -> [Vertex] +getVertices (Just (PolygonPath ps)) = ps +getVertices Nothing = [] + -- | checks whether the distance of a vertex constructed by 'fromAngle' to the origin is 1 prop_VertexFromAngleDistance :: Double -> Bool prop_VertexFromAngleDistance angle = abs (1 - vertexDistance (fromAngle angle)) < epsilon @@ -25,6 +37,25 @@ prop_MoveSelfEqualsScale2 p = move p p == scale 2 p prop_MoveNegativeSelfEqualsOrigin :: Vertex -> Bool prop_MoveNegativeSelfEqualsOrigin p = move p (scale (-1) p) == Point (0, 0) +-- | checks whether distance of points of a regular polygon have the radius as distance from the origin +prop_RegularPolygonPointsDistance :: Integral a => (PolygonVertexCount a, Positive Double) -> Bool +prop_RegularPolygonPointsDistance (PolygonVertexCount n, r) = all (\p -> abs (vertexDistance p - getPositive r) < epsilon) (getVertices (regularPolygon (fromIntegral n) (getPositive r) (Point (0, 0)))) + +-- | checks whether the average of all polygon points equals the specified centre point +prop_RegularPolygonCentre :: (Integral a) => (PolygonVertexCount a, Positive Double, Vertex) -> Bool +prop_RegularPolygonCentre (PolygonVertexCount n, r, p) = abs (specX - calcX) < epsilon && abs (specY - calcY) < epsilon + where + Point (specX, specY) = p + Point (calcX, calcY) = scale (1 / fromIntegral n) $ foldr move (Point (0, 0)) (getVertices (regularPolygon (fromIntegral n) (getPositive r) p)) + +-- | checks whether the distance of all points of a star from the centre can be partitioned into two classes, +-- both of the same size, the number of spikes +prop_StarDistancePartitioning :: (Integral a) => (PolygonVertexCount a, Positive Double, Positive Double) -> Bool +prop_StarDistancePartitioning (PolygonVertexCount n, r1, r2) = length c1 == length c2 && length c1 == fromIntegral n + where + (c1, c2) = partition (\x -> abs (getPositive r1 - vertexDistance x) > abs (getPositive r2 - vertexDistance x)) vertices + vertices = getVertices (star (fromIntegral n) (getPositive r1) (getPositive r2) (Point (0, 0))) + return [] check = $quickCheckAll