Test.QuickCheck

| QuickCheck-2.1.1.1: Automatic testing of Haskell programs | Contents | Index
Test.QuickCheck
Contents
Running tests Random generation Generator combinators Generators which use Arbitrary Generator debugging Arbitrary and CoArbitrary classes. Helper functions for implementing arbitrary Helper functions for implementing shrink Helper functions for implementing coarbitrary Type-level modifiers for changing generator behavior Properties Property combinators Handling failure Test distribution Text formatting
Synopsis
quickCheck :: Testable prop => prop -> IO ()
data Args = Args {
replay :: Maybe (StdGen, Int)
maxSuccess :: Int
maxDiscard :: Int
maxSize :: Int
}
data Result
= Success {
labels :: [(String, Int)]
}
| GaveUp {
numTests :: Int
labels :: [(String, Int)]
}
| Failure {
usedSeed :: StdGen
usedSize :: Int
reason :: String
labels :: [(String, Int)]
}
| NoExpectedFailure {
labels :: [(String, Int)]
}
stdArgs :: Args
quickCheckWith :: Testable prop => Args -> prop -> IO ()
quickCheckWithResult :: Testable prop => Args -> prop -> IO Result
quickCheckResult :: Testable prop => prop -> IO Result
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
arbitrary :: Gen a
shrink :: a -> [a]
class CoArbitrary a where
coarbitrary :: a -> Gen c -> Gen c
arbitrarySizedIntegral :: Num a => Gen a
arbitrarySizedFractional :: Fractional 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
property :: prop -> Property
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
whenFail :: Testable prop => IO () -> 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 ()
Tests a property and prints the results to stdout.
data Args
Args specifies arguments to the QuickCheck driver
Constructors
Args |
replay :: Maybe (StdGen, Int) | should we replay a previous test?
maxSuccess :: Int | maximum number of successful tests before succeeding
maxDiscard :: Int | maximum number of discarded tests before giving up
maxSize :: Int | size to use for the biggest test cases
Instances
Read Args |
Show Args |
data Result
Result represents the test result
Constructors
Success |
labels :: [(String, Int)] | labels and frequencies found during all tests
GaveUp |
numTests :: Int | number of successful tests performed
labels :: [(String, Int)] | labels and frequencies found during all tests
Failure |
usedSeed :: StdGen | what seed was used
usedSize :: Int | what was the test size
reason :: String | what was the reason
labels :: [(String, Int)] | labels and frequencies found during all tests
NoExpectedFailure |
labels :: [(String, Int)] | labels and frequencies found during all tests
Instances
Read Result |
Show Result |
stdArgs :: Args
stdArgs are the default test arguments used
quickCheckWith :: Testable prop => Args -> prop -> IO ()
Tests a property, using test arguments, and prints the results to stdout.
quickCheckWithResult :: Testable prop => Args -> prop -> IO Result
Tests a property, using test arguments, produces a test result, and prints the results to stdout.
quickCheckResult :: Testable prop => prop -> IO Result
Tests a property, produces a test result, and prints the results to stdout.
Random generation
data Gen a
Instances
Monad Gen |
Functor Gen |
Applicative Gen |
Testable prop => Testable (Gen prop) |
Generator combinators
sized :: (Int -> Gen a) -> Gen a
Used to construct generators that depend on the size parameter.
resize :: Int -> Gen a -> Gen a
Overrides the size parameter. Returns a generator which uses the given size instead of the runtime-size parameter.
choose :: Random a => (a, a) -> Gen a
Generates a random element in the given inclusive range.
promote :: Monad m => m (Gen a) -> Gen (m a)
Promotes a generator to a generator of monadic values.
suchThat :: Gen a -> (a -> Bool) -> Gen a
Generates a value that satisfies a predicate.
suchThatMaybe :: Gen a -> (a -> Bool) -> Gen (Maybe a)
Tries to generate a value that satisfies a predicate.
oneof :: [Gen a] -> Gen a
Randomly uses one of the given generators. The input list must be non-empty.
frequency :: [(Int, Gen a)] -> Gen a
Chooses one of the given generators, with a weighted random distribution. The input list must be non-empty.
elements :: [a] -> Gen a
Generates one of the given values. The input list must be non-empty.
growingElements :: [a] -> Gen a
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 non-empty.
listOf :: Gen a -> Gen [a]
Generates a list of random length. The maximum length depends on the size parameter.
listOf1 :: Gen a -> Gen [a]
Generates a non-empty list of random length. The maximum length depends on the size parameter.
vectorOf :: Int -> Gen a -> Gen [a]
Generates a list of the given length.
Generators which use Arbitrary
vector :: Arbitrary a => Int -> Gen [a]
Generates a list of a given length.
orderedList :: (Ord a, Arbitrary a) => Gen [a]
Generates an ordered list of a given length.
Generator debugging
sample :: Show a => Gen a -> IO ()
Generates some example values and prints them to stdout.
sample' :: Gen a -> IO [a]
Generates some example values.
Arbitrary and CoArbitrary classes.
class Arbitrary a where
Random generation and shrinking of values.
Methods
arbitrary :: Gen a
A generator for values of the given type.
shrink :: a -> [a]
Produces a (possibly) empty list of all the possible immediate shrinks of the given value.
Instances
Arbitrary Bool |
Arbitrary Char |
Arbitrary Double |
Arbitrary Float |
Arbitrary Int |
Arbitrary Integer |
Arbitrary () |
Arbitrary OrdC |
Arbitrary OrdB |
Arbitrary OrdA |
Arbitrary C |
Arbitrary B |
Arbitrary A |
Arbitrary a => Arbitrary [a] |
(Integral a, Arbitrary a) => Arbitrary (Ratio a) |
Arbitrary a => Arbitrary (Maybe a) |
(RealFloat a, Arbitrary a) => Arbitrary (Complex a) |
Arbitrary a => Arbitrary (Smart a) |
Arbitrary a => Arbitrary (Shrink2 a) |
(Num a, Ord a, Arbitrary a) => Arbitrary (NonNegative a) |
(Num a, Ord a, Arbitrary a) => Arbitrary (NonZero a) |
(Num a, Ord a, Arbitrary a) => Arbitrary (Positive a) |
Arbitrary a => Arbitrary (NonEmptyList a) |
(Ord a, Arbitrary a) => Arbitrary (OrderedList a) |
Arbitrary a => Arbitrary (Fixed a) |
Arbitrary a => Arbitrary (Blind a) |
(CoArbitrary a, Arbitrary b) => Arbitrary (a -> b) |
(Arbitrary a, Arbitrary b) => Arbitrary (Either a b) |
(Arbitrary a, Arbitrary b) => Arbitrary (a, b) |
(Arbitrary a, ShrinkState s a) => Arbitrary (Shrinking s a) |
(FunArbitrary a, Arbitrary b) => Arbitrary (Fun a b) |
(FunArbitrary a, Arbitrary c) => Arbitrary (:-> a c) |
(Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (a, b, c) |
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => Arbitrary (a, b, c, d) |
(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e) => Arbitrary (a, b, c, d, e) |
class CoArbitrary a where
Used for random generation of functions.
Methods
coarbitrary :: a -> Gen c -> Gen c
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`.
Instances
CoArbitrary Bool |
CoArbitrary Char |
CoArbitrary Double |
CoArbitrary Float |
CoArbitrary Int |
CoArbitrary Integer |
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 a
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 a
Generates a fractional number. The number can be positive or negative and its maximum absolute value depends on the size parameter.
arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a
Generates an integral number. The number is chosen from the entire range of the type.
arbitraryBoundedRandom :: (Bounded a, Random a) => Gen a
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]
Returns no shrinking alternatives.
shrinkIntegral :: Integral a => a -> [a]
Shrink an integral number.
shrinkRealFrac :: RealFrac a => a -> [a]
Shrink a fraction.
Helper functions for implementing coarbitrary
variant :: Integral n => n -> Gen a -> Gen a
Modifies a generator using an integer seed.
(><) :: (Gen a -> Gen a) -> (Gen a -> Gen a) -> Gen a -> Gen a
Combine two generator perturbing functions, for example the results of calls to `variant` or `coarbitrary`.
coarbitraryIntegral :: Integral a => a -> Gen b -> Gen b
A `coarbitrary` implementation for integral numbers.
coarbitraryReal :: Real a => a -> Gen b -> Gen b
A `coarbitrary` implementation for real numbers.
coarbitraryShow :: Show a => a -> Gen b -> Gen b
`coarbitrary` helper for lazy people :-).
Type-level modifiers for changing generator behavior
newtype Blind a
`Blind x`: as x, but x does not have to be in the `Show` class.
Constructors
Blind a |
Instances
Enum a => Enum (Blind a) |
Eq a => Eq (Blind a) |
Integral a => Integral (Blind a) |
Num a => Num (Blind a) |
Ord a => Ord (Blind a) |
Real a => Real (Blind a) |
Show (Blind a) |
Arbitrary a => Arbitrary (Blind a) |
newtype Fixed a
`Fixed x`: as x, but will not be shrunk.
Constructors
Fixed a |
Instances
Enum a => Enum (Fixed a) |
Eq a => Eq (Fixed a) |
Integral a => Integral (Fixed a) |
Num a => Num (Fixed a) |
Ord a => Ord (Fixed a) |
Read a => Read (Fixed a) |
Real a => Real (Fixed a) |
Show a => Show (Fixed a) |
Arbitrary a => Arbitrary (Fixed a) |
newtype OrderedList a
`Ordered xs`: guarantees that xs is ordered.
Constructors
Ordered [a] |
Instances
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
`NonEmpty xs`: guarantees that xs is non-empty.
Constructors
NonEmpty [a] |
Instances
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) |
newtype Positive a
`Positive x`: guarantees that `x > 0`.
Constructors
Positive a |
Instances
Enum a => Enum (Positive a) |
Eq a => Eq (Positive a) |
Integral a => Integral (Positive a) |
Num a => Num (Positive a) |
Ord a => Ord (Positive a) |
Read a => Read (Positive a) |
Real a => Real (Positive a) |
Show a => Show (Positive a) |
(Num a, Ord a, Arbitrary a) => Arbitrary (Positive a) |
newtype NonZero a
`NonZero x`: guarantees that `x /= 0`.
Constructors
NonZero a |
Instances
Enum a => Enum (NonZero a) |
Eq a => Eq (NonZero a) |
Integral a => Integral (NonZero a) |
Num a => Num (NonZero a) |
Ord a => Ord (NonZero a) |
Read a => Read (NonZero a) |
Real a => Real (NonZero a) |
Show a => Show (NonZero a) |
(Num a, Ord a, Arbitrary a) => Arbitrary (NonZero a) |
newtype NonNegative a
`NonNegative x`: guarantees that `x >= 0`.
Constructors
NonNegative a |
Instances
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) |
data Smart a
`Smart _ x`: tries a different order when shrinking.
Constructors
Smart Int a |
Instances
Show a => Show (Smart a) |
Arbitrary a => Arbitrary (Smart a) |
newtype Shrink2 a
`Shrink2 x`: allows 2 shrinking steps at the same time when shrinking x
Constructors
Shrink2 a |
Instances
Enum a => Enum (Shrink2 a) |
Eq a => Eq (Shrink2 a) |
Integral a => Integral (Shrink2 a) |
Num a => Num (Shrink2 a) |
Ord a => Ord (Shrink2 a) |
Read a => Read (Shrink2 a) |
Real a => Real (Shrink2 a) |
Show a => Show (Shrink2 a) |
Arbitrary a => Arbitrary (Shrink2 a) |
data Shrinking s a
`Shrinking _ x`: allows for maintaining a state during shrinking.
Constructors
Shrinking s a |
Instances
Show a => Show (Shrinking s a) |
(Arbitrary a, ShrinkState s a) => Arbitrary (Shrinking s a) |
class ShrinkState s a where
Methods
shrinkInit :: a -> s
shrinkState :: a -> s -> [(a, s)]
Properties
type Property = Gen Prop
data Prop
Instances
Testable Prop |
class Testable prop where
The class of things which can be tested, i.e. turned into a property.
Methods
property :: prop -> Property
Instances
Testable Bool |
Testable () |
Testable Result |
Testable Prop |
Testable prop => Testable (Gen prop) |
(Arbitrary a, Show a, Testable prop) => Testable (a -> prop) |
Property combinators
mapSize :: Testable prop => (Int -> Int) -> prop -> Property
Changes the maximum test case size for a property.
shrinking
:: Testable prop |
=> (a -> [a]) | `shrink`-like function.
-> 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 weh you want to override the default behavior.
(==>) :: Testable prop => Bool -> prop -> Property
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) -> Property
Explicit universal quantification: uses an explicitly given test case generator.
forAllShrink :: (Show a, Testable prop) => Gen a -> (a -> [a]) -> (a -> prop) -> Property
Like `forAll`, but tries to shrink the argument for failing test cases.
(.&.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property
Handling failure
whenFail :: Testable prop => IO () -> prop -> Property
Performs an `IO` action after the last failure of a property.
whenFail' :: Testable prop => IO () -> prop -> Property
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 -> Property
Modifies a property so that it is expected to fail for some test cases.
within :: Testable prop => Int -> prop -> Property
Considers a property failed if it does not complete within the given number of microseconds.
Test distribution
label :: Testable prop => String -> prop -> Property
Attaches a label to a property. This is used for reporting test case distribution.
collect :: (Show a, Testable prop) => a -> prop -> Property
Labels a property with a value:
     collect x = label (show x)
classify
:: Testable prop |
=> Bool | `True` if the test case should be labelled.
-> String | Label.
-> prop |
-> Property |
Conditionally labels test case.
cover
:: Testable prop |
=> Bool | `True` if the test case belongs to the class.
-> Int | The required percentage (0-100) 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.
Text formatting
newtype Str
Constructors
MkStr String |
Instances
Show Str |
ranges :: Integral a => a -> a -> Str
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