我已经为使用Pipes的项目编写了一个程序,我很喜欢!我正在努力对我的代码进行单元测试。
我有一系列类型的函数Pipe In Out IO ()
(例如),我希望使用HSpec进行测试。我该怎么办?
例如,假设我有这个域:
data Person = Person String Int | Unknown deriving (Show, Eq)
data Classification = Friend | Foe | Undecided deriving Show
和这个管道:
classify :: Pipe Person (Person, Classification) IO ()
classify = do
p@(Person name _) <- await
case name of
"Alex" -> yield (p, Friend)
"Bob" -> yield (p, Foe)
_ -> yield (p, Undecided)
我想写一个规范:
main = hspec $ do
describe "readFileP" $
it "yields all the lines of a file"
pendingWith "How can I test this Pipe? :("
诀窍是使用toListM
来自Pipes ListT
monad的变压器。
import Pipes
import qualified Pipes.Prelude as P
import Test.Hspec
data Person = Person String Int | Unknown deriving (Show, Eq)
data Classification = Friend | Foe | Undecided deriving (Show, Eq)
classify :: Pipe Person (Person, Classification) IO ()
classify = do
p@(Person name _) <- await
case name of
"Alex" -> yield (p, Friend)
"Bob" -> yield (p, Foe)
_ -> yield (p, Undecided)
该测试使用ListT转换器将管道转换为ListT并使用HSpec进行断言:
main = hspec $ do
describe "classify" $ do
it "correctly finds friends" $ do
[(p, cl)] <- P.toListM $ each [Person "Alex" 31] >-> classify
p `shouldBe` (Person "Alex" 31)
cl `shouldBe` Friend
请注意,您不必使用each
,这可以是调用的简单生产者yield
。
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