使用QuickCheck为给定功能生成多个任意参数 [英] Using QuickCheck to generate multiple arbitrary parameters for a given function

问题描述

上下文

我具有以下功能:

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

我想做类似的事情:

-- instance PrivKey RSA.PrivateKey RSA.PublicKey where...
genRSA :: Gen RSA.PrivateKey
genRSAMessage :: Gen BS.ByteString

main = do
  quickCheck . verbose 
  $ forAll genRSA 
  $ forAll genRSAMessage prop_SignAndVerify

也就是说，我想使用显式生成器在prop_SignAndVerify的参数中为Blind a和BS.ByteString生成任意值.

That is, I would like to use explicit generators to generate arbitrary values for Blind a and BS.ByteString in the parameters of prop_SignAndVerify.

但是，上面的代码不起作用，因为函数forAll具有类型签名:

The code above, however, doesn't work, because the function forAll has type signature:

forAll :: (Show a, Testable prop) => Gen a -> (a -> prop) -> Property

此函数运行生成器，并将生成的任意值苹果化为(a -> prop)，并返回Property.但是，该Property不能进一步部分应用.它隐藏了基础功能.

This function runs the generator and apples the generated arbitrary value to (a -> prop), returning a Property. This Property however cannot be further partially applied; it hides the underlying function.

我认为我们需要上述工作才能实现:

I think what we need for the above to work would be something like:

forAll' :: (Show a,  Testable prop) => Gen a -> (a -> prop) -> prop

问题

所以我的问题是，如何在prop_SignAndVerify的参数上使用genRSA和genRSAMessage，还是有替代方法?

So my question is, how can I use genRSA and genRSAMessage over the parameters of prop_SignAndVerify, or is there an alternative approach?

谢谢

推荐答案

您可以利用Gen的单调性质从属性中组合出更复杂的Gen值:

You could take advantage of the monadic nature of Gen to compose a more complex Gen value from your property:

main =
  let g = do
            key <- genRSA
            message <- genRSAMessage
            return $ prop_SignAndVerify (Blind key) message
  in quickCheck . verbose $ forAll g id

在这里，g是Gen Bool值.

或者，您可以利用Gen的应用性质，并使用<*>编写g:

Alternatively, you can take advantage of the applicative nature of Gen and compose g using <*>:

main =
  let g =
        return (\key message -> prop_SignAndVerify (Blind key) message)
        <*> genRSA
        <*> genRSAMessage
  in quickCheck . verbose $ forAll g id

在这里

g仍然是Gen Bool值.

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