Safe Haskell	None
Language	Haskell2010

Test.Tasty.Hedgehog.Coverage

Contents

Data types
Test helpers
Coverage functions
Property Config Helpers

Description

Provide some functionality for tracking the distribution of test inputs when using Hedgehog property-based testing.

Synopsis

data Cover = Cover {
- _coverageConf :: !PropertyConfig
- _coverageProp :: PropertyT (StateT Tally IO) ()
}
newtype Tally = Tally {
- unTally :: Map Text Int
}
testPropertyCoverage :: TestName -> Cover -> TestTree
withCoverage :: HasCallStack => PropertyT (StateT Tally IO) () -> Cover
classify :: MonadState Tally m => Bool -> Text -> m ()
label :: MonadState Tally m => Text -> m ()
collect :: (MonadState Tally m, Show a) => a -> m ()
withTests :: TestLimit -> Cover -> Cover
withRetries :: ShrinkRetries -> Cover -> Cover
withDiscards :: DiscardLimit -> Cover -> Cover
withShrinks :: ShrinkLimit -> Cover -> Cover

Data types

data Cover Source #

Equivalent to the Property type from Hedgehog, but slightly modified for the purpose of enabling the classification functionality.

Constructors

Cover
Fields _coverageConf :: !PropertyConfig _coverageProp :: PropertyT (StateT Tally IO) ()

newtype Tally Source #

This is the type used to store the information about the inputs.

Constructors

Tally
Fields unTally :: Map Text Int

Instances

Eq Tally Source #
Instance details Defined in Test.Tasty.Hedgehog.Coverage Methods (==) :: Tally -> Tally -> Bool # (/=) :: Tally -> Tally -> Bool #
Show Tally Source #
Instance details Defined in Test.Tasty.Hedgehog.Coverage Methods showsPrec :: Int -> Tally -> ShowS # show :: Tally -> String # showList :: [Tally] -> ShowS #

Test helpers

testPropertyCoverage :: TestName -> Cover -> TestTree Source #

Create a TestTree using a Cover property test.

withCoverage :: HasCallStack => PropertyT (StateT Tally IO) () -> Cover Source #

Simiar to the property function in Hedgehog, this creates a Cover that lets us track the required information.

Coverage functions

classify Source #

Arguments

:: MonadState Tally m
=> Bool	`True` if this case should be included.
-> Text	The label for this input.
-> m ()

Records how many test cases satisfy a given condition.

prop_reverse_involutive :: Cover
prop_reverse_involutive = withCoverage $ do
  xs <- forAll $ Gen.list (Range.linear 0 100) Gen.alpha
  classify (length xs > 50) "non-trivial"
  test_involutive reverse xs

Which gives output similar to:

 reverse involutive:          OK
   18.00% non-trivial

label Source #

Arguments

:: MonadState Tally m
=> Text	The label for the input.
-> m ()

Attach a simple label to a property.

prop_reverse_reverse :: Cover
prop_reverse_reverse = withCoverage $ do
  xs <- forAll $ Gen.list (Range.linear 0 100) Gen.alpha
  label ("length of input is " ++ show (length xs))
  reverse (reverse xs) === xs

Which gives output similar to:

reverse involutive:          OK
    4.00% with a length of 0
    7.00% with a length of 1
    3.00% with a length of 11
    2.00% with a length of 12
    2.00% with a length of 13
    ...

collect Source #

Arguments

:: (MonadState Tally m, Show a)
=> a	The input to collect.
-> m ()

Uses the input itself as the label, useful for recording test case distribution.

prop_reverse_reverse :: Cover
prop_reverse_reverse = withCoverage $ do
  xs <- forAll $ Gen.list (Range.linear 0 100) Gen.alpha
  collect (length xs)
  reverse (reverse xs) === xs

Which gives output similar to:

reverse involutive:          OK
    8.00% ""
    1.00% "AFkNJBLiWYEBFRyZhulpMkkqIvsDpLAmaYoFTnNNFfkrbPUqDIRUuZOFGohTfB"
    1.00% "AWWfLCfmZPoydVYXwnFHyCEWztXanEzdoc"
    1.00% "CJJVBGOeaIkLfcOUGV"
    1.00% "CNrTsblqfEz"
    1.00% "CxDqm"

Property Config Helpers

These functions work exactly as their original Hedgehog counterparts, only modified to work with the Cover type.

withTests :: TestLimit -> Cover -> Cover Source #

Set the number of times a property should be executed before it is considered successful.

If you have a test that does not involve any generators and thus does not need to run repeatedly, you can use withTests 1 to define a property that will only be checked once.

withRetries :: ShrinkRetries -> Cover -> Cover Source #

Set the number of times a property will be executed for each shrink before the test runner gives up and tries a different shrink. See ShrinkRetries for more information.

withDiscards :: DiscardLimit -> Cover -> Cover Source #

Set the number of times a property is allowed to discard before the test runner gives up.

withShrinks :: ShrinkLimit -> Cover -> Cover Source #

Set the number of times a property is allowed to shrink before the test runner gives up and prints the counterexample.