Add simple property tests for Vertex

This commit is contained in:
Simon Bruder 2022-12-27 20:02:46 +01:00
parent 872954f492
commit b36bdaa076
Signed by: simon
GPG key ID: 8D3C82F9F309F8EC
2 changed files with 38 additions and 0 deletions

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@ -15,6 +15,11 @@ instance Arbitrary Vertex where
y <- arbitrary
return (Point (x, y))
-- | 'vertexDistance' @p@
-- returns the distance of a vertex to the origin
vertexDistance :: Vertex -> Double
vertexDistance (Point (x, y)) = sqrt (x ** 2 + y ** 2)
-- | 'fromAngle' @angle@
-- creates a point on the unit circle at the specified angle
-- (specified in radians).

33
genstar/Test.hs Normal file
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@ -0,0 +1,33 @@
{-# LANGUAGE TemplateHaskell #-}
module Test where
import Main (Vertex (Point), fromAngle, move, scale, vertexDistance)
import Test.QuickCheck (discard, quickCheck, quickCheckAll)
-- | the largest acceptable difference between two doubles so they are considered equal
epsilon :: Double
epsilon = 1e-10
-- | 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
-- | checks whether the distance of a vertex scaled by an factor is multiplied by that factor (absolute).
prop_VertexScaleDistance :: (Vertex, Double) -> Bool
prop_VertexScaleDistance (p, s) = abs (abs s * vertexDistance p - vertexDistance (scale s p)) < epsilon
-- | checks whether moving a vertex by itself equals scaling it by 2
prop_MoveSelfEqualsScale2 :: Vertex -> Bool
prop_MoveSelfEqualsScale2 p = move p p == scale 2 p
-- | checks whether moving a vertex by itself scaled by -1 equals the origin
prop_MoveNegativeSelfEqualsOrigin :: Vertex -> Bool
prop_MoveNegativeSelfEqualsOrigin p = move p (scale (-1) p) == Point (0, 0)
return []
check = $quickCheckAll
main :: IO Bool
main = check