使用Haskell QuickCheck测试TCP端口验证器

Question

我（第一次）尝试使用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"

我写了这样一个任意的例子：

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

但我不知道如何编写测试属性。

Answer 1

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

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.

Answer 2

正如jev答案的附录一样，您还可以通过使用自定义Gens:来享受松散耦合的测试框架

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 "...")