 quickCheck :: Testable prop => prop > IO ()
 data Args = Args {}
 data Result
 = Success { }
  GaveUp { }
  Failure { }
  NoExpectedFailure { }
 stdArgs :: Args
 quickCheckWith :: Testable prop => Args > prop > IO ()
 quickCheckWithResult :: Testable prop => Args > prop > IO Result
 quickCheckResult :: Testable prop => prop > IO Result
 verboseCheck :: Testable prop => prop > IO ()
 verboseCheckWith :: Testable prop => Args > prop > IO ()
 verboseCheckWithResult :: Testable prop => Args > prop > IO Result
 verboseCheckResult :: Testable prop => prop > IO Result
 verbose :: Testable prop => prop > Property
 data Gen a
 sized :: (Int > Gen a) > Gen a
 resize :: Int > Gen a > Gen a
 choose :: Random a => (a, a) > Gen a
 promote :: Monad m => m (Gen a) > Gen (m a)
 suchThat :: Gen a > (a > Bool) > Gen a
 suchThatMaybe :: Gen a > (a > Bool) > Gen (Maybe a)
 oneof :: [Gen a] > Gen a
 frequency :: [(Int, Gen a)] > Gen a
 elements :: [a] > Gen a
 growingElements :: [a] > Gen a
 listOf :: Gen a > Gen [a]
 listOf1 :: Gen a > Gen [a]
 vectorOf :: Int > Gen a > Gen [a]
 vector :: Arbitrary a => Int > Gen [a]
 orderedList :: (Ord a, Arbitrary a) => Gen [a]
 sample :: Show a => Gen a > IO ()
 sample' :: Gen a > IO [a]
 class Arbitrary a where
 class CoArbitrary a where
 coarbitrary :: a > Gen c > Gen c
 arbitrarySizedIntegral :: Num a => Gen a
 arbitrarySizedFractional :: Fractional a => Gen a
 arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen a
 arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a
 arbitraryBoundedRandom :: (Bounded a, Random a) => Gen a
 shrinkNothing :: a > [a]
 shrinkIntegral :: Integral a => a > [a]
 shrinkRealFrac :: RealFrac a => a > [a]
 variant :: Integral n => n > Gen a > Gen a
 (><) :: (Gen a > Gen a) > (Gen a > Gen a) > Gen a > Gen a
 coarbitraryIntegral :: Integral a => a > Gen b > Gen b
 coarbitraryReal :: Real a => a > Gen b > Gen b
 coarbitraryShow :: Show a => a > Gen b > Gen b
 newtype Blind a = Blind a
 newtype Fixed a = Fixed a
 newtype OrderedList a = Ordered [a]
 newtype NonEmptyList a = NonEmpty [a]
 newtype Positive a = Positive a
 newtype NonZero a = NonZero a
 newtype NonNegative a = NonNegative a
 data Smart a = Smart Int a
 newtype Shrink2 a = Shrink2 a
 data Shrinking s a = Shrinking s a
 class ShrinkState s a where
 shrinkInit :: a > s
 shrinkState :: a > s > [(a, s)]
 type Property = Gen Prop
 data Prop
 class Testable prop where
 mapSize :: Testable prop => (Int > Int) > prop > Property
 shrinking :: Testable prop => (a > [a]) > a > (a > prop) > Property
 (==>) :: Testable prop => Bool > prop > Property
 forAll :: (Show a, Testable prop) => Gen a > (a > prop) > Property
 forAllShrink :: (Show a, Testable prop) => Gen a > (a > [a]) > (a > prop) > Property
 (.&.) :: (Testable prop1, Testable prop2) => prop1 > prop2 > Property
 (.&&.) :: (Testable prop1, Testable prop2) => prop1 > prop2 > Property
 conjoin :: Testable prop => [prop] > Property
 (..) :: (Testable prop1, Testable prop2) => prop1 > prop2 > Property
 disjoin :: Testable prop => [prop] > Property
 whenFail :: Testable prop => IO () > prop > Property
 printTestCase :: Testable prop => String > prop > Property
 whenFail' :: Testable prop => IO () > prop > Property
 expectFailure :: Testable prop => prop > Property
 within :: Testable prop => Int > prop > Property
 label :: Testable prop => String > prop > Property
 collect :: (Show a, Testable prop) => a > prop > Property
 classify :: Testable prop => Bool > String > prop > Property
 cover :: Testable prop => Bool > Int > String > prop > Property
 newtype Str = MkStr String
 ranges :: Integral a => a > a > Str
Running tests
quickCheck :: Testable prop => prop > IO ()Source
Tests a property and prints the results to stdout
.
Args specifies arguments to the QuickCheck driver
Result represents the test result
Success  
GaveUp  
Failure  
 
NoExpectedFailure  
quickCheckWith :: Testable prop => Args > prop > IO ()Source
Tests a property, using test arguments, and prints the results to stdout
.
quickCheckWithResult :: Testable prop => Args > prop > IO ResultSource
Tests a property, using test arguments, produces a test result, and prints the results to stdout
.
quickCheckResult :: Testable prop => prop > IO ResultSource
Tests a property, produces a test result, and prints the results to stdout
.
Running tests verbosely
verboseCheck :: Testable prop => prop > IO ()Source
Tests a property and prints the results and all test cases generated to stdout
.
This is just a convenience function that means the same as quickCheck
.
verbose
.
verboseCheckWith :: Testable prop => Args > prop > IO ()Source
Tests a property, using test arguments, and prints the results and all test cases generated to stdout
.
This is just a convenience function that combines quickCheckWith
and verbose
.
verboseCheckWithResult :: Testable prop => Args > prop > IO ResultSource
Tests a property, using test arguments, produces a test result, and prints the results and all test cases generated to stdout
.
This is just a convenience function that combines quickCheckWithResult
and verbose
.
verboseCheckResult :: Testable prop => prop > IO ResultSource
Tests a property, produces a test result, and prints the results and all test cases generated to stdout
.
This is just a convenience function that combines quickCheckResult
and verbose
.
verbose :: Testable prop => prop > PropertySource
Prints out the generated testcase every time the property is tested,
like verboseCheck
from QuickCheck 1.
Only variables quantified over inside the verbose
are printed.
Random generation
Generator combinators
sized :: (Int > Gen a) > Gen aSource
Used to construct generators that depend on the size parameter.
resize :: Int > Gen a > Gen aSource
Overrides the size parameter. Returns a generator which uses the given size instead of the runtimesize parameter.
promote :: Monad m => m (Gen a) > Gen (m a)Source
Promotes a monadic generator to a generator of monadic values.
suchThatMaybe :: Gen a > (a > Bool) > Gen (Maybe a)Source
Tries to generate a value that satisfies a predicate.
oneof :: [Gen a] > Gen aSource
Randomly uses one of the given generators. The input list must be nonempty.
frequency :: [(Int, Gen a)] > Gen aSource
Chooses one of the given generators, with a weighted random distribution. The input list must be nonempty.
growingElements :: [a] > Gen aSource
Takes a list of elements of increasing size, and chooses among an initial segment of the list. The size of this initial segment increases with the size parameter. The input list must be nonempty.
listOf :: Gen a > Gen [a]Source
Generates a list of random length. The maximum length depends on the size parameter.
listOf1 :: Gen a > Gen [a]Source
Generates a nonempty list of random length. The maximum length depends on the size parameter.
Generators which use Arbitrary
orderedList :: (Ord a, Arbitrary a) => Gen [a]Source
Generates an ordered list of a given length.
Generator debugging
Arbitrary and CoArbitrary classes.
Random generation and shrinking of values.
A generator for values of the given type.
Produces a (possibly) empty list of all the possible immediate shrinks of the given value.
class CoArbitrary a whereSource
Used for random generation of functions.
coarbitrary :: a > Gen c > Gen cSource
Used to generate a function of type a > c
. The implementation
should use the first argument to perturb the random generator
given as the second argument. the returned generator
is then used to generate the function result.
You can often use variant
and ><
to implement
coarbitrary
.
CoArbitrary Bool  
CoArbitrary Char  
CoArbitrary Double  
CoArbitrary Float  
CoArbitrary Int  
CoArbitrary Int8  
CoArbitrary Int16  
CoArbitrary Int32  
CoArbitrary Int64  
CoArbitrary Integer  
CoArbitrary Word  
CoArbitrary Word8  
CoArbitrary Word16  
CoArbitrary Word32  
CoArbitrary Word64  
CoArbitrary ()  
CoArbitrary OrdC  
CoArbitrary OrdB  
CoArbitrary OrdA  
CoArbitrary C  
CoArbitrary B  
CoArbitrary A  
CoArbitrary a => CoArbitrary [a]  
(Integral a, CoArbitrary a) => CoArbitrary (Ratio a)  
CoArbitrary a => CoArbitrary (Maybe a)  
(RealFloat a, CoArbitrary a) => CoArbitrary (Complex a)  
(Arbitrary a, CoArbitrary b) => CoArbitrary (a > b)  
(CoArbitrary a, CoArbitrary b) => CoArbitrary (Either a b)  
(CoArbitrary a, CoArbitrary b) => CoArbitrary (a, b)  
(CoArbitrary a, CoArbitrary b, CoArbitrary c) => CoArbitrary (a, b, c)  
(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d) => CoArbitrary (a, b, c, d)  
(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d, CoArbitrary e) => CoArbitrary (a, b, c, d, e) 
Helper functions for implementing arbitrary
arbitrarySizedIntegral :: Num a => Gen aSource
Generates an integral number. The number can be positive or negative and its maximum absolute value depends on the size parameter.
arbitrarySizedFractional :: Fractional a => Gen aSource
Generates a fractional number. The number can be positive or negative and its maximum absolute value depends on the size parameter.
arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen aSource
Generates an integral number from a bounded domain. The number is chosen from the entire range of the type, but small numbers are generated more often than big numbers. Inspired by demands from Phil Wadler.
arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen aSource
Generates an integral number. The number is chosen uniformly from
the entire range of the type. You may want to use
arbitrarySizedBoundedIntegral
instead.
arbitraryBoundedRandom :: (Bounded a, Random a) => Gen aSource
Generates an element of a bounded type. The element is chosen from the entire range of the type.
Helper functions for implementing shrink
shrinkNothing :: a > [a]Source
Returns no shrinking alternatives.
shrinkIntegral :: Integral a => a > [a]Source
Shrink an integral number.
shrinkRealFrac :: RealFrac a => a > [a]Source
Shrink a fraction.
Helper functions for implementing coarbitrary
(><) :: (Gen a > Gen a) > (Gen a > Gen a) > Gen a > Gen aSource
Combine two generator perturbing functions, for example the
results of calls to variant
or coarbitrary
.
coarbitraryIntegral :: Integral a => a > Gen b > Gen bSource
A coarbitrary
implementation for integral numbers.
coarbitraryReal :: Real a => a > Gen b > Gen bSource
A coarbitrary
implementation for real numbers.
coarbitraryShow :: Show a => a > Gen b > Gen bSource
coarbitrary
helper for lazy people :).
Typelevel modifiers for changing generator behavior
Fixed x
: as x, but will not be shrunk.
Fixed a 
newtype OrderedList a Source
Ordered xs
: guarantees that xs is ordered.
Ordered [a] 
Eq a => Eq (OrderedList a)  
Ord a => Ord (OrderedList a)  
Read a => Read (OrderedList a)  
Show a => Show (OrderedList a)  
(Ord a, Arbitrary a) => Arbitrary (OrderedList a) 
newtype NonEmptyList a Source
NonEmpty xs
: guarantees that xs is nonempty.
NonEmpty [a] 
Eq a => Eq (NonEmptyList a)  
Ord a => Ord (NonEmptyList a)  
Read a => Read (NonEmptyList a)  
Show a => Show (NonEmptyList a)  
Arbitrary a => Arbitrary (NonEmptyList a) 
Positive x
: guarantees that x > 0
.
Positive a 
NonZero x
: guarantees that x /= 0
.
NonZero a 
newtype NonNegative a Source
NonNegative x
: guarantees that x >= 0
.
Enum a => Enum (NonNegative a)  
Eq a => Eq (NonNegative a)  
Integral a => Integral (NonNegative a)  
Num a => Num (NonNegative a)  
Ord a => Ord (NonNegative a)  
Read a => Read (NonNegative a)  
Real a => Real (NonNegative a)  
Show a => Show (NonNegative a)  
(Num a, Ord a, Arbitrary a) => Arbitrary (NonNegative a) 
Smart _ x
: tries a different order when shrinking.
Shrink2 x
: allows 2 shrinking steps at the same time when shrinking x
Shrink2 a 
Shrinking _ x
: allows for maintaining a state during shrinking.
Shrinking s a 
class ShrinkState s a whereSource
shrinkInit :: a > sSource
shrinkState :: a > s > [(a, s)]Source
Properties
class Testable prop whereSource
The class of things which can be tested, i.e. turned into a property.
Property combinators
mapSize :: Testable prop => (Int > Int) > prop > PropertySource
Changes the maximum test case size for a property.
:: Testable prop  
=> (a > [a]) 

> a  The original argument 
> (a > prop)  
> Property 
Shrinks the argument to property if it fails. Shrinking is done automatically for most types. This is only needed when you want to override the default behavior.
(==>) :: Testable prop => Bool > prop > PropertySource
Implication for properties: The resulting property holds if
the first argument is False
, or if the given property holds.
forAll :: (Show a, Testable prop) => Gen a > (a > prop) > PropertySource
Explicit universal quantification: uses an explicitly given test case generator.
forAllShrink :: (Show a, Testable prop) => Gen a > (a > [a]) > (a > prop) > PropertySource
Like forAll
, but tries to shrink the argument for failing test cases.
Handling failure
whenFail :: Testable prop => IO () > prop > PropertySource
Performs an IO
action after the last failure of a property.
printTestCase :: Testable prop => String > prop > PropertySource
Prints a message to the terminal as part of the counterexample.
whenFail' :: Testable prop => IO () > prop > PropertySource
Performs an IO
action every time a property fails. Thus,
if shrinking is done, this can be used to keep track of the
failures along the way.
expectFailure :: Testable prop => prop > PropertySource
Modifies a property so that it is expected to fail for some test cases.
within :: Testable prop => Int > prop > PropertySource
Considers a property failed if it does not complete within the given number of microseconds.
Test distribution
label :: Testable prop => String > prop > PropertySource
Attaches a label to a property. This is used for reporting test case distribution.
collect :: (Show a, Testable prop) => a > prop > PropertySource
Labels a property with a value:
collect x = label (show x)
:: Testable prop  
=> Bool 

> String  Label. 
> prop  
> Property 
Conditionally labels test case.
:: Testable prop  
=> Bool 

> Int  The required percentage (0100) of test cases. 
> String  Label for the test case class. 
> prop  
> Property 
Checks that at least the given proportion of the test cases belong to the given class.