quickcheck

问题 ...instead of generating 100 new random samples for each property? My testsuite contains the TemplateHaskell hack explained here [1] to test all functions named prop_*. Running the test program prints === prop_foo from tests/lala.lhs:20 === +++ OK, passed 100 tests. === prop_bar from tests/lala.lhs:28 === +++ OK, passed 100 tests. and it looks like going through 100 random samples for each of the properties. Problemis: Generating the samples is quite expensive, checking the properties is not.

问题 ...instead of generating 100 new random samples for each property? My testsuite contains the TemplateHaskell hack explained here [1] to test all functions named prop_*. Running the test program prints === prop_foo from tests/lala.lhs:20 === +++ OK, passed 100 tests. === prop_bar from tests/lala.lhs:28 === +++ OK, passed 100 tests. and it looks like going through 100 random samples for each of the properties. Problemis: Generating the samples is quite expensive, checking the properties is not.

问题 I have a property that takes a list of Strings: myProp :: [String] -> Bool I need to constrain the inputs that QuickCheck generates so that only non-empty strings are in the list. How can I do this? 回答1: You use forAll together with listOf (which generates lists) and listOf1 (which generates non-empty lists). Examples quickCheck $ forAll (listOf $ listOf1 arbitrary) $ myProp -- more verbose alternative to make things clear nonEmptyString :: Gen String nonEmptyString = listOf1 arbitrary

问题 I was trying to write a QuickCheck test for the identity f $ y = f y My initial plan was to write an arbitrary generator that returns functions & Integer, having the signature Gen (Int -> Int, Int) and in the prop_DollerDoesNothing test that function application with / without the $ gives the same result. This was my code: prop_DollarDoesNothing :: Property prop_DollarDoesNothing = forAll arbitraryFuncInt (\(f, y) -> (f $ y) == (f y)) arbitraryFuncInt :: Gen (Int -> Int, Int) arbitraryFuncInt

问题 I was trying to write a QuickCheck test for the identity f $ y = f y My initial plan was to write an arbitrary generator that returns functions & Integer, having the signature Gen (Int -> Int, Int) and in the prop_DollerDoesNothing test that function application with / without the $ gives the same result. This was my code: prop_DollarDoesNothing :: Property prop_DollarDoesNothing = forAll arbitraryFuncInt (\(f, y) -> (f $ y) == (f y)) arbitraryFuncInt :: Gen (Int -> Int, Int) arbitraryFuncInt

问题 I'm getting an error that says the module doesn't exist when I try to runhaskell. It's odd because I try to install it first and says its up to date. Any idea how to fix this? 回答1: You could try creating the package environment in the local directory that holds your project, like this: c:\Users\...\ex1haskell> cabal install --lib --package-env . QuickCheck This should create a file of the form .ghc.environment.xxx in ex1haskell , which hopefully should be picked up by runhaskell / ghci / ghc

问题 Context I have the following function: prop_SignAndVerify :: (PrivKey a b) => Blind a -> BS.ByteString -> Bool prop_SignAndVerify bsk msg = case verify pk msg sig of Left e -> error e Right b -> b where sk = getBlind bsk pk = toPublic sk sig = case sign sk msg of Left e -> error e Right s -> s I would like to do something like: -- instance PrivKey RSA.PrivateKey RSA.PublicKey where... genRSA :: Gen RSA.PrivateKey genRSAMessage :: Gen BS.ByteString main = do quickCheck . verbose $ forAll

问题 My ghci version is 8.4.3 I tried stack install QuickCheck Something was installed. But when I input import Test.QuickCheck , it tells Could not find module ‘Test.QuickCheck’ again. How can I fix it? 回答1: Firstly, stack install is not recommended for installing executables or libraries. Instead, there's a couple of things you can do to use the QuickCheck library: If you want to use QuickCheck in a command such as stack ghci or stack ghc , you can add it as a --package option e.g. to run a REPL

问题 I have the following code I am using for creating a challenge on the following site : codewars describe "Random cases" $ do it "It should handle random test cases" $ property $ prop_check where prop_check (Positive x) = solution x == ref_sol x --- ref_sol function I would like to set the value of x in prop_check to be a positive int greater than 4 and at max a five-digit number (no more than five digits, i.e : max value = 99999). How would I go about approaching it ? 回答1: You can use

问题 I have the following code fastShuffle :: [a] -> IO [a] fastShuffle a = <some code> prop_fastShuffle_correct :: [Int] -> Property prop_fastShuffle_correct s = monadicIO ( do sh <- run (fastShuffle s) return ( True ==> ( insertionSort sh == insertionSort s && if length s > 10 then s /= sh else True ) ) ) And .. it is working. I can't understand how what looks to be a pure function ( prop_fastShuffle_correct ) can call a non pure function that has side effects ( fastShuffle ). Hope that someone