retry-0.7.6.3: test/Tests/Control/Retry.hs
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Tests.Control.Retry
( tests
) where
-------------------------------------------------------------------------------
import Control.Applicative
import Control.Concurrent
import Control.Concurrent.STM as STM
import Control.Exception (AsyncException (..), IOException,
MaskingState (..),
getMaskingState, throwTo)
import Control.Monad.Catch
import Control.Monad.Identity
import Control.Monad.IO.Class
import Control.Monad.Writer.Strict
import Data.Default.Class (def)
import Data.Either
import Data.IORef
import Data.List
import Data.Maybe
import Data.Time.Clock
import Data.Time.LocalTime ()
import Data.Typeable
import Hedgehog as HH
import qualified Hedgehog.Gen as Gen
import qualified Hedgehog.Range as Range
import System.IO.Error
import Test.Tasty
import Test.Tasty.Hedgehog
import Test.Tasty.HUnit (assertBool, testCase, (@?=))
-------------------------------------------------------------------------------
import Control.Retry
-------------------------------------------------------------------------------
tests :: TestTree
tests = testGroup "Control.Retry"
[ recoveringTests
, monoidTests
, retryStatusTests
, quadraticDelayTests
, policyTransformersTests
, maskingStateTests
, capDelayTests
, limitRetriesByCumulativeDelayTests
]
-------------------------------------------------------------------------------
recoveringTests :: TestTree
recoveringTests = testGroup "recovering"
[ testProperty "recovering test without quadratic retry delay" $ property $ do
startTime <- liftIO getCurrentTime
timeout <- forAll (Gen.int (Range.linear 0 15))
retries <- forAll (Gen.int (Range.linear 0 50))
res <- liftIO $ try $ recovering
(constantDelay timeout <> limitRetries retries)
testHandlers
(const $ throwM (userError "booo"))
endTime <- liftIO getCurrentTime
HH.assert (isLeftAnd isUserError res)
let ms' = (fromInteger . toInteger $ (timeout * retries)) / 1000000.0
HH.assert (diffUTCTime endTime startTime >= ms')
, testGroup "exception hierarchy semantics"
[ testCase "does not catch async exceptions" $ do
counter <- newTVarIO (0 :: Int)
done <- newEmptyMVar
let work = atomically (modifyTVar' counter succ) >> threadDelay 1000000
tid <- forkIO $
recoverAll (limitRetries 2) (const work) `finally` putMVar done ()
atomically (STM.check . (== 1) =<< readTVar counter)
throwTo tid UserInterrupt
takeMVar done
count <- atomically (readTVar counter)
count @?= 1
, testCase "recovers from custom exceptions" $ do
f <- mkFailN Custom1 2
res <- try $ recovering
(constantDelay 5000 <> limitRetries 3)
[const $ Handler $ \ Custom1 -> return shouldRetry]
f
(res :: Either Custom1 ()) @?= Right ()
, testCase "fails beyond policy using custom exceptions" $ do
f <- mkFailN Custom1 3
res <- try $ recovering
(constantDelay 5000 <> limitRetries 2)
[const $ Handler $ \ Custom1 -> return shouldRetry]
f
(res :: Either Custom1 ()) @?= Left Custom1
, testCase "recoverAll won't catch exceptions which are not decendants of SomeException" $ do
f <- mkFailN Custom1 4
res <- try $ recoverAll
(constantDelay 5000 <> limitRetries 3)
f
(res :: Either Custom1 ()) @?= Left Custom1
, testCase "does not recover from unhandled exceptions" $ do
f <- mkFailN Custom2 2
res <- try $ recovering
(constantDelay 5000 <> limitRetries 5)
[const $ Handler $ \ Custom1 -> return shouldRetry]
f
(res :: Either Custom2 ()) @?= Left Custom2
, testCase "recovers in presence of multiple handlers" $ do
f <- mkFailN Custom2 2
res <- try $ recovering
(constantDelay 5000 <> limitRetries 5)
[ const $ Handler $ \ Custom1 -> return shouldRetry
, const $ Handler $ \ Custom2 -> return shouldRetry ]
f
(res :: Either Custom2 ()) @?= Right ()
, testCase "general exceptions catch specific ones" $ do
f <- mkFailN Custom2 2
res <- try $ recovering
(constantDelay 5000 <> limitRetries 5)
[ const $ Handler $ \ (_::SomeException) -> return shouldRetry ]
f
(res :: Either Custom2 ()) @?= Right ()
, testCase "(redundant) even general catchers don't go beyond policy" $ do
f <- mkFailN Custom2 3
res <- try $ recovering
(constantDelay 5000 <> limitRetries 2)
[ const $ Handler $ \ (_::SomeException) -> return shouldRetry ]
f
(res :: Either Custom2 ()) @?= Left Custom2
, testCase "rethrows in presence of failed exception casts" $ do
f <- mkFailN Custom2 3
final <- try $ do
res <- try $ recovering
(constantDelay 5000 <> limitRetries 2)
[ const $ Handler $ \ (_::SomeException) -> return shouldRetry ]
f
(res :: Either Custom1 ()) @?= Left Custom1
final @?= Left Custom2
]
]
-------------------------------------------------------------------------------
monoidTests :: TestTree
monoidTests = testGroup "Policy is a monoid"
[ testProperty "left identity" $ property $
propIdentity (\p -> mempty <> p) id
, testProperty "right identity" $ property $
propIdentity (\p -> p <> mempty) id
, testProperty "associativity" $ property $
propAssociativity (\x y z -> x <> (y <> z)) (\x y z -> (x <> y) <> z)
]
where
propIdentity left right = do
retryStatus <- forAll genRetryStatus
fixedDelay <- forAll (Gen.maybe (Gen.int (Range.linear 0 maxBound)))
let calculateDelay _rs = fixedDelay
let applyPolicy' f = getRetryPolicyM (f $ retryPolicy calculateDelay) retryStatus
validRes = maybe True (>= 0)
l <- liftIO $ applyPolicy' left
r <- liftIO $ applyPolicy' right
if validRes r && validRes l
then l === r
else return ()
propAssociativity left right = do
retryStatus <- forAll genRetryStatus
let genDelay = Gen.maybe (Gen.int (Range.linear 0 maxBound))
delayA <- forAll genDelay
delayB <- forAll genDelay
delayC <- forAll genDelay
let applyPolicy' f = liftIO $ getRetryPolicyM (f (retryPolicy (const delayA)) (retryPolicy (const delayB)) (retryPolicy (const delayC))) retryStatus
res <- liftIO (liftA2 (==) (applyPolicy' left) (applyPolicy' right))
assert res
-------------------------------------------------------------------------------
retryStatusTests :: TestTree
retryStatusTests = testGroup "retry status"
[ testCase "passes the correct retry status each time" $ do
let policy = limitRetries 2 <> constantDelay 100
rses <- gatherStatuses policy
rsIterNumber <$> rses @?= [0, 1, 2]
rsCumulativeDelay <$> rses @?= [0, 100, 200]
rsPreviousDelay <$> rses @?= [Nothing, Just 100, Just 100]
]
-------------------------------------------------------------------------------
policyTransformersTests :: TestTree
policyTransformersTests = testGroup "policy transformers"
[ testProperty "always produces positive delay with positive constants (no rollover)" $ property $ do
delay <- forAll (Gen.int (Range.linear 0 maxBound))
let res = runIdentity (simulatePolicy 1000 (exponentialBackoff delay))
delays = catMaybes (snd <$> res)
mnDelay = if null delays
then Nothing
else Just (minimum delays)
case mnDelay of
Nothing -> return ()
Just n -> do
footnote (show n ++ " is not >= 0")
HH.assert (n >= 0)
, testProperty "positive, nonzero exponential backoff is always incrementing" $ property $ do
delay <- forAll (Gen.int (Range.linear 1 maxBound))
let res = runIdentity (simulatePolicy 1000 (limitRetriesByDelay maxBound (exponentialBackoff delay)))
delays = catMaybes (snd <$> res)
sort delays === delays
length (group delays) === length delays
]
-------------------------------------------------------------------------------
maskingStateTests :: TestTree
maskingStateTests = testGroup "masking state"
[ testCase "shouldn't change masking state in a recovered action" $ do
maskingState <- getMaskingState
final <- try $ recovering def testHandlers $ const $ do
maskingState' <- getMaskingState
maskingState' @?= maskingState
fail "Retrying..."
assertBool
("Expected IOException but didn't get one")
(isLeft (final :: Either IOException ()))
, testCase "should mask asynchronous exceptions in exception handlers" $ do
let checkMaskingStateHandlers =
[ const $ Handler $ \(_ :: SomeException) -> do
maskingState <- getMaskingState
maskingState @?= MaskedInterruptible
return shouldRetry
]
final <- try $ recovering def checkMaskingStateHandlers $ const $ fail "Retrying..."
assertBool
("Expected IOException but didn't get one")
(isLeft (final :: Either IOException ()))
]
-------------------------------------------------------------------------------
capDelayTests :: TestTree
capDelayTests = testGroup "capDelay"
[ testProperty "respects limitRetries" $ property $ do
retries <- forAll (Gen.int (Range.linear 1 100))
cap <- forAll (Gen.int (Range.linear 1 maxBound))
let policy = capDelay cap (limitRetries retries)
let delays = runIdentity (simulatePolicy (retries + 1) policy)
let Just lastDelay = lookup (retries - 1) delays
let Just gaveUp = lookup retries delays
let noDelay = 0
lastDelay === Just noDelay
gaveUp === Nothing
, testProperty "does not allow any delays higher than the given delay" $ property $ do
cap <- forAll (Gen.int (Range.linear 1 maxBound))
baseDelay <- forAll (Gen.int (Range.linear 1 100))
basePolicy <- forAllWith (const "RetryPolicy") (genScalingPolicy baseDelay)
let policy = capDelay cap basePolicy
let delays = catMaybes (snd <$> runIdentity (simulatePolicy 100 policy))
let baddies = filter (> cap) delays
baddies === []
]
-------------------------------------------------------------------------------
-- | Generates policies that increase on each iteration
genScalingPolicy :: (Alternative m) => Int -> m (RetryPolicyM Identity)
genScalingPolicy baseDelay =
(pure (exponentialBackoff baseDelay) <|> pure (fibonacciBackoff baseDelay))
-------------------------------------------------------------------------------
limitRetriesByCumulativeDelayTests :: TestTree
limitRetriesByCumulativeDelayTests = testGroup "limitRetriesByCumulativeDelay"
[ testProperty "never exceeds the given cumulative delay" $ property $ do
baseDelay <- forAll (Gen.int (Range.linear 1 100))
basePolicy <- forAllWith (const "RetryPolicy") (genScalingPolicy baseDelay)
cumulativeDelayMax <- forAll (Gen.int (Range.linear 1 10000))
let policy = limitRetriesByCumulativeDelay cumulativeDelayMax basePolicy
let delays = catMaybes (snd <$> runIdentity (simulatePolicy 100 policy))
footnoteShow delays
let actualCumulativeDelay = sum delays
footnote (show actualCumulativeDelay <> " <= " <> show cumulativeDelayMax)
HH.assert (actualCumulativeDelay <= cumulativeDelayMax)
]
-------------------------------------------------------------------------------
quadraticDelayTests :: TestTree
quadraticDelayTests = testGroup "quadratic delay"
[ testProperty "recovering test with quadratic retry delay" $ property $ do
startTime <- liftIO getCurrentTime
timeout <- forAll (Gen.int (Range.linear 0 15))
retries <- forAll (Gen.int (Range.linear 0 8))
res <- liftIO $ try $ recovering
(exponentialBackoff timeout <> limitRetries retries)
[const $ Handler (\(_::SomeException) -> return True)]
(const $ throwM (userError "booo"))
endTime <- liftIO getCurrentTime
HH.assert (isLeftAnd isUserError res)
let tmo = if retries > 0 then timeout * 2 ^ (retries - 1) else 0
let ms' = ((fromInteger . toInteger $ tmo) / 1000000.0)
HH.assert (diffUTCTime endTime startTime >= ms')
]
-------------------------------------------------------------------------------
isLeftAnd :: (a -> Bool) -> Either a b -> Bool
isLeftAnd f ei = case ei of
Left v -> f v
_ -> False
testHandlers :: [a -> Handler IO Bool]
testHandlers = [const $ Handler (\(_::SomeException) -> return shouldRetry)]
data Custom1 = Custom1 deriving (Eq,Show,Read,Ord,Typeable)
data Custom2 = Custom2 deriving (Eq,Show,Read,Ord,Typeable)
instance Exception Custom1
instance Exception Custom2
-------------------------------------------------------------------------------
genRetryStatus :: MonadGen m => m RetryStatus
genRetryStatus = do
n <- Gen.int (Range.linear 0 maxBound)
d <- Gen.int (Range.linear 0 maxBound)
l <- Gen.maybe (Gen.int (Range.linear 0 d))
return $ defaultRetryStatus { rsIterNumber = n
, rsCumulativeDelay = d
, rsPreviousDelay = l}
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-- | Create an action that will fail exactly N times with the given
-- exception and will then return () in any subsequent calls.
mkFailN :: (Exception e) => e -> Int -> IO (s -> IO ())
mkFailN e n = do
r <- newIORef 0
return $ const $ do
old <- atomicModifyIORef' r $ \ old -> (old+1, old)
case old >= n of
True -> return ()
False -> throwM e
-------------------------------------------------------------------------------
gatherStatuses
:: MonadIO m
=> RetryPolicyM (WriterT [RetryStatus] m)
-> m [RetryStatus]
gatherStatuses policy = execWriterT $
retrying policy (\_ _ -> return shouldRetry)
(\rs -> tell [rs])
-------------------------------------------------------------------------------
-- | Just makes things a bit easier to follow instead of a magic value
-- of @return True@
shouldRetry :: Bool
shouldRetry = True