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module Test.VeriFuzz.Graph.Random where
import Data.Graph.Inductive (Graph, LEdge, mkGraph)
import Test.QuickCheck (Arbitrary, Gen, arbitrary, generate,
infiniteListOf, resize, suchThat)
arbitraryEdge :: (Arbitrary e) => Int -> Gen (LEdge e)
arbitraryEdge n = do
x <- with $ \a -> a < n && a > 0 && a /= n-1
y <- with $ \a -> x < a && a < n && a > 0
z <- arbitrary
return (x, y, z)
where
with = suchThat . resize n $ arbitrary
randomDAG :: (Arbitrary l, Arbitrary e, Graph gr)
=> Int -- ^ The number of nodes
-> Gen (gr l e) -- ^ The generated graph. It uses Arbitrary to
-- generate random instances of each node
randomDAG n = do
list <- infiniteListOf $ arbitrary
l <- infiniteListOf $ arbitraryEdge n
return . mkGraph (nodes list) $ take (10*n) l
where
nodes l = zip [0..n] $ take n l
genRandomDAG :: (Arbitrary l, Arbitrary e, Graph gr)
=> Int
-> IO (gr l e)
genRandomDAG = generate . randomDAG
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