[英]How to use QuickCheck to test database related functions?
我需要測試許多訪問數據庫的函數(通過Persistent)。 雖然我可以使用monadicIO
和withSqlitePool
來執行此操作, withSqlitePool
會導致測試效率低下。 每個測試,而不是屬性,但測試,將創建和銷毀數據庫池。 我該如何防止這種情況?
重要提示:忘記效率或優雅。 我甚至無法使QuickCheck
和Persistent
類型構成。
instance (Monad a) => MonadThrow (PropertyM a)
instance (MonadThrow a) => MonadCatch (PropertyM a)
type NwApp = SqlPersistT IO
prop_childCreation :: PropertyM NwApp Bool
prop_childCreation = do
uid <- pick $ UserKey <$> arbitrary
lid <- pick $ LogKey <$> arbitrary
gid <- pick $ Aria2Gid <$> arbitrary
let createDownload_ = createDownload gid lid uid []
(Entity pid _) <- run $ createDownload_ Nothing
dstatus <- pick arbitrary
parent <- run $ updateGet pid [DownloadStatus =. dstatus]
let test = do
(Entity cid child) <- run $ createDownload_ (Just pid)
case (parent ^. status, child ^. status) of
(DownloadComplete ChildrenComplete, DownloadComplete ChildrenNone) -> return True
(DownloadComplete ChildrenIncomplete, DownloadIncomplete) -> return True
_ -> return False
test `catches` [
Handler (\ (e :: SanityException) -> return True),
Handler (\ (e :: SomeException) -> return False)
]
-- How do I write this function?
runTests = monadicIO $ runSqlite ":memory:" $ do
-- whatever I do, this function fails to typecheck
為了避免創建和銷毀數據庫池並僅設置數據庫一次,您需要在外部的main
函數中使用withSqliteConn
,然后轉換每個屬性以使用該連接,如下面的代碼所示:
share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persistLowerCase|
Person
name String
age Int Maybe
deriving Show Eq
|]
type SqlT m = SqlPersistT (NoLoggingT (ResourceT m))
prop_insert_person :: PropertyM (SqlT IO) ()
prop_insert_person = do
personName <- pick arbitrary
personAge <- pick arbitrary
let person = Person personName personAge
-- This assertion will fail right now on the second iteration
-- since I have not implemented the cleanup code
numEntries <- run $ count ([] :: [Filter Person])
assert (numEntries == 0)
personId <- run $ insert person
result <- run $ get personId
assert (result == Just person)
main :: IO ()
main = runNoLoggingT $ withSqliteConn ":memory:" $ \connection -> lift $ do
let
-- Run a SqlT action using our connection
runSql :: SqlT IO a -> IO a
runSql = flip runSqlPersistM connection
runSqlProperty :: SqlT IO Property -> Property
runSqlProperty action = ioProperty . runSql $ do
prop <- action
liftIO $ putStrLn "\nDB reset code (per test) goes here\n"
return prop
quickCheckSql :: PropertyM (SqlT IO) () -> IO ()
quickCheckSql = quickCheck . monadic runSqlProperty
-- Initial DB setup code
runSql $ runMigration migrateAll
-- Test as many quickcheck properties as you like
quickCheckSql prop_insert_person
完整的代碼包括導入和擴展可以在這個要點中找到。
請注意,我沒有實現在測試之間清理數據庫的功能,因為我不知道如何通常使用持久性,你必須自己實現(替換剛剛打印消息的占位符清理操作) 。
對於PropertyM
您也不需要MonadCatch
/ MonadThrow
實例。 相反,你應該趕上NwApp
monad。 所以不是這樣的:
let test = do
run a
...
run b
test `catch` \exc -> ...
您應該使用以下代碼:
let test = do
a
b
return ...whether or not the test was successfull...
let testCaught = test `catch` \exc -> ..handler code...
ok <- test
assert ok
(.lhs位於: http ://lpaste.net/173182)
使用的包:
build-depends: base >= 4.7 && < 5, QuickCheck, persistent, persistent-sqlite, monad-logger, transformers
首先,一些進口:
{-# LANGUAGE OverloadedStrings #-}
module Lib2 where
import Database.Persist.Sql
import Database.Persist.Sqlite
import Test.QuickCheck
import Test.QuickCheck.Monadic
import Control.Monad.Logger
import Control.Monad.Trans.Class
這是我們要測試的查詢:
aQuery :: SqlPersistM Int
aQuery = undefined
當然, aQuery
可能需要參數。 重要的是它返回一個SqlPersistM
動作。
以下是如何運行SqlPersistM
操作:
runQuery = runSqlite ":memory:" $ do aQuery
盡管PropertyM
是monad變換器,但似乎唯一有用的方法是使用PropertyM IO
。
為了從SqlPersistM-action中獲取IO動作,我們需要后端。
考慮到這些,這是一個示例數據庫測試:
prop_test :: SqlBackend -> PropertyM IO Bool
prop_test backend = do
a <- run $ runSqlPersistM aQuery backend
b <- run $ runSqlPersistM aQuery backend
return (a == b)
這里的run
與lift
相同。
要使用特定后端運行SqlPersistM操作,我們需要執行一些提升:
runQuery2 = withSqliteConn ":memory:" $ \backend -> do
liftNoLogging (runSqlPersistM aQuery backend)
liftNoLogging :: Monad m => m a -> NoLoggingT m a
liftNoLogging = lift
說明:
runSqlPersistM aQuery backend
是一個IO動作 withSqliteConn ...
需要一個具有日志記錄的withSqliteConn ...
動作 liftNoLogging
函數將IO動作提升到NoLoggingT IO動作 最后,通過quickCheck運行prop_test:
runTest = withSqliteConn ":memory:" $ \backend -> do
liftNoLogging $ quickCheck (monadicIO (prop_test backend))
monadicIO :: PropertyM IO a -> Property
runSqlite ":memory:" :: SqlPersistT (NoLoggingT (ResourceT m)) a -> m a
prop_childCreation :: PropertyM NwApp Bool
這些不會構成。 其中一個不屬於。
monadic :: Monad m => (m Property -> Property) -> PropertyM m a -> Property
這看起來比monadicIO
:我們可以將這個和我們的要求結合起來,將prop_childCreation用於生成需求(m Property - > Property)。
runSqlite ":memory:" :: SqlPersistT (NoLoggingT (ResourceT m)) a -> m a
\f -> monadic f prop_childCreation :: (NwApp Property -> Property) -> Property
重寫NwApp以便於查找:
runSqlite ":memory:" :: SqlPersistT (NoLoggingT (ResourceT m)) a -> m a
\f -> monadic f prop_childCreation :: (SqlPersistT IO Property -> Property) -> Property
我只相信T
末端的所有東西都是MonadTrans
,這意味着我們有lift :: Monad m => ma -> T ma
。 然后我們可以看到這是我們擺脫SqlPersistT的機會:
\f g -> monadic (f . runSqlite ":memory:" . g) prop_childCreation :: (IO Property -> Property) -> (SqlPersistT IO Property -> SqlPersistT (NoLoggingT (ResourceT m)) Property) -> Property
我們需要再次擺脫IO,所以monadicIO可能會幫助我們:
\f g -> monadic (monadicIO . f . runSqlite ":memory:" . g) prop_childCreation :: (IO Property -> PropertyT IO a) -> (SqlPersistT IO Property -> SqlPersistT (NoLoggingT (ResourceT m)) Property) -> Property
電梯閃耀的時間! 除了在f中我們顯然將IO Property
的Property
拋出,並且在右邊我們需要以某種方式“fmap”到SqlPersistT的monad參數部分。 好吧,我們可以忽略第一個問題,並將另一個問題推遲到下一步:
\f -> monadic (monadicIO . lift . runSqlite ":memory:" . f (lift . lift)) prop_childCreation :: ((m a -> n a) -> SqlPersistT m a -> SqlPersist n a) -> Property
結果看起來就像Control.Monad.Morph
的MFunctor
提供的那樣。 我只是假裝SqlPersistT有一個實例:
monadic (monadicIO . lift . runSqlite ":memory:" . mmorph (lift . lift)) prop_childCreation :: Property
田田! 祝你好運,也許這會有所幫助。
exference項目試圖使我剛剛完成的過程自動化。 我聽說過,只要我把f和g之類的參數放進去,就會讓ghc告訴你應該去哪種類型。
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