haskell - 使用 Haskell QuickCheck 测试 TCP 端口验证器

Question

我正在尝试（第一次）使用 QuickCheck 来测试一个验证 TCP 端口号的函数：

validatePort :: Int -> Either String Int
validatePort port =
  if port > 0 && port <= 65535
    then Right port
    else Left "Port must be between 1 and 65535 inclusive"

我写了一个这样的任意实例：

instance Arbitrary Int where
  arbitrary = choose (1, 65535)

但我不确定如何编写测试属性。

Answer 1

作为 jev 答案的附录，您还可以通过使用 custom 来享受松散耦合的测试框架Gen：

validPorts :: Gen Int
validPorts = choose (1, 65535)

invalidPorts :: Gen Int
invalidPorts = oneof [choose (minBound, 0), choose (65536, maxBound)]

prop_validatePortValidatesValidPorts = 
  forAll validPorts (\port -> validatePort port == Right port)

prop_validatePortDoesNotValidateInvalidPorts =
  forAll invalidPorts (\port -> validatePort port == Left "...")

Answer 2

作为起点，首先： import Test.QuickCheck它已经为 Int 定义了 Arbitrary 实例

然后写一个属性：

prop_validate_port port = 
  if   port > 0 && port <= 65535
  then validatePort port == Right port
  else validatePort port == Left "Port must be between 1 and 65535 inclusive"

并运行测试：

>quickCheck prop_validate_port
>+++ OK. passed 100 tests.