| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Test.Tasty.QuickCheck
Contents
Description
This module allows to use QuickCheck properties in tasty.
Synopsis
- testProperty :: Testable a => TestName -> a -> TestTree
- testProperties :: TestName -> [(String, Property)] -> TestTree
- newtype QuickCheckTests = QuickCheckTests Int
- newtype QuickCheckReplay = QuickCheckReplay (Maybe Int)
- newtype QuickCheckShowReplay = QuickCheckShowReplay Bool
- newtype QuickCheckMaxSize = QuickCheckMaxSize Int
- newtype QuickCheckMaxRatio = QuickCheckMaxRatio Int
- newtype QuickCheckVerbose = QuickCheckVerbose Bool
- monomorphic :: Name -> ExpQ
- polyVerboseCheck :: Name -> ExpQ
- polyQuickCheck :: Name -> ExpQ
- pattern Success :: Int -> [(String, Double)] -> String -> Result
- pattern GaveUp :: Int -> [(String, Double)] -> String -> Result
- pattern Failure :: Int -> Int -> Int -> Int -> QCGen -> Int -> String -> Maybe AnException -> [(String, Double)] -> String -> [String] -> Result
- pattern NoExpectedFailure :: Int -> [(String, Double)] -> String -> Result
- pattern InsufficientCoverage :: Int -> [(String, Double)] -> String -> Result
- labels :: Result -> [(String, Double)]
- reason :: Result -> String
- theException :: Result -> Maybe AnException
- numTests :: Result -> Int
- output :: Result -> String
- numShrinks :: Result -> Int
- numShrinkTries :: Result -> Int
- numShrinkFinal :: Result -> Int
- usedSeed :: Result -> QCGen
- usedSize :: Result -> Int
- failingTestCase :: Result -> [String]
- total :: NFData a => a -> Property
- (===) :: (Eq a, Show a) => a -> a -> Property
- disjoin :: Testable prop => [prop] -> Property
- (.||.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property
- conjoin :: Testable prop => [prop] -> Property
- (.&&.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property
- (.&.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property
- forAllShrink :: (Show a, Testable prop) => Gen a -> (a -> [a]) -> (a -> prop) -> Property
- forAll :: (Show a, Testable prop) => Gen a -> (a -> prop) -> Property
- within :: Testable prop => Int -> prop -> Property
- (==>) :: Testable prop => Bool -> prop -> Property
- cover :: Testable prop => Bool -> Int -> String -> prop -> Property
- classify :: Testable prop => Bool -> String -> prop -> Property
- collect :: (Show a, Testable prop) => a -> prop -> Property
- label :: Testable prop => String -> prop -> Property
- withMaxSuccess :: Testable prop => Int -> prop -> Property
- again :: Testable prop => prop -> Property
- once :: Testable prop => prop -> Property
- expectFailure :: Testable prop => prop -> Property
- whenFail' :: Testable prop => IO () -> prop -> Property
- whenFail :: Testable prop => IO () -> prop -> Property
- printTestCase :: Testable prop => String -> prop -> Property
- counterexample :: Testable prop => String -> prop -> Property
- noShrinking :: Testable prop => prop -> Property
- shrinking :: Testable prop => (a -> [a]) -> a -> (a -> prop) -> Property
- mapSize :: Testable prop => (Int -> Int) -> prop -> Property
- ioProperty :: Testable prop => IO prop -> Property
- data Property
- class Testable prop where
- data Discard = Discard
- applyFun3 :: Fun (a, b, c) d -> a -> b -> c -> d
- applyFun2 :: Fun (a, b) c -> a -> b -> c
- applyFun :: Fun a b -> a -> b
- functionMap :: Function b => (a -> b) -> (b -> a) -> (a -> c) -> a :-> c
- pattern Fn :: forall a b. (a -> b) -> Fun a b
- pattern Fn2 :: forall a b c. (a -> b -> c) -> Fun (a, b) c
- pattern Fn3 :: forall a b c d. (a -> b -> c -> d) -> Fun (a, b, c) d
- class Function a where
- data Fun a b = Fun (a :-> b, b, Shrunk) (a -> b)
- newtype Blind a = Blind {
- getBlind :: a
- newtype Fixed a = Fixed {
- getFixed :: a
- newtype OrderedList a = Ordered {
- getOrdered :: [a]
- newtype NonEmptyList a = NonEmpty {
- getNonEmpty :: [a]
- data InfiniteList a = InfiniteList {
- getInfiniteList :: [a]
- infiniteListInternalData :: InfiniteListInternalData a
- newtype Positive a = Positive {
- getPositive :: a
- newtype NonZero a = NonZero {
- getNonZero :: a
- newtype NonNegative a = NonNegative {
- getNonNegative :: a
- newtype Large a = Large {
- getLarge :: a
- newtype Small a = Small {
- getSmall :: a
- newtype Shrink2 a = Shrink2 {
- getShrink2 :: a
- data Smart a = Smart Int a
- data Shrinking s a = Shrinking s a
- class ShrinkState s a where
- newtype ASCIIString = ASCIIString {}
- newtype UnicodeString = UnicodeString {}
- newtype PrintableString = PrintableString {}
- infiniteList :: Arbitrary a => Gen [a]
- orderedList :: (Ord a, Arbitrary a) => Gen [a]
- vector :: Arbitrary a => Int -> Gen [a]
- coarbitraryEnum :: Enum a => a -> Gen b -> Gen b
- coarbitraryShow :: Show a => a -> Gen b -> Gen b
- coarbitraryReal :: Real a => a -> Gen b -> Gen b
- coarbitraryIntegral :: Integral a => a -> Gen b -> Gen b
- (><) :: (Gen a -> Gen a) -> (Gen a -> Gen a) -> Gen a -> Gen a
- genericCoarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b
- shrinkRealFrac :: RealFrac a => a -> [a]
- shrinkIntegral :: Integral a => a -> [a]
- shrinkMapBy :: (a -> b) -> (b -> a) -> (a -> [a]) -> b -> [b]
- shrinkMap :: Arbitrary a => (a -> b) -> (b -> a) -> b -> [b]
- shrinkNothing :: a -> [a]
- arbitraryPrintableChar :: Gen Char
- arbitraryASCIIChar :: Gen Char
- arbitraryUnicodeChar :: Gen Char
- arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen a
- arbitraryBoundedEnum :: (Bounded a, Enum a) => Gen a
- arbitraryBoundedRandom :: (Bounded a, Random a) => Gen a
- arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a
- arbitrarySizedFractional :: Fractional a => Gen a
- arbitrarySizedNatural :: Integral a => Gen a
- arbitrarySizedIntegral :: Integral a => Gen a
- applyArbitrary4 :: (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => (a -> b -> c -> d -> r) -> Gen r
- applyArbitrary3 :: (Arbitrary a, Arbitrary b, Arbitrary c) => (a -> b -> c -> r) -> Gen r
- applyArbitrary2 :: (Arbitrary a, Arbitrary b) => (a -> b -> r) -> Gen r
- shrinkList :: (a -> [a]) -> [a] -> [[a]]
- subterms :: (Generic a, GSubterms (Rep a) a) => a -> [a]
- recursivelyShrink :: (Generic a, RecursivelyShrink (Rep a)) => a -> [a]
- genericShrink :: (Generic a, RecursivelyShrink (Rep a), GSubterms (Rep a) a) => a -> [a]
- shrink2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => f a b -> [f a b]
- arbitrary2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => Gen (f a b)
- shrink1 :: (Arbitrary1 f, Arbitrary a) => f a -> [f a]
- arbitrary1 :: (Arbitrary1 f, Arbitrary a) => Gen (f a)
- class Arbitrary a where
- class Arbitrary1 (f :: * -> *) where
- class Arbitrary2 (f :: * -> * -> *) where
- class CoArbitrary a where
- infiniteListOf :: Gen a -> Gen [a]
- vectorOf :: Int -> Gen a -> Gen [a]
- listOf1 :: Gen a -> Gen [a]
- listOf :: Gen a -> Gen [a]
- growingElements :: [a] -> Gen a
- shuffle :: [a] -> Gen [a]
- sublistOf :: [a] -> Gen [a]
- elements :: [a] -> Gen a
- frequency :: [(Int, Gen a)] -> Gen a
- oneof :: [Gen a] -> Gen a
- suchThatMaybe :: Gen a -> (a -> Bool) -> Gen (Maybe a)
- suchThatMap :: Gen a -> (a -> Maybe b) -> Gen b
- suchThat :: Gen a -> (a -> Bool) -> Gen a
- sample :: Show a => Gen a -> IO ()
- sample' :: Gen a -> IO [a]
- generate :: Gen a -> IO a
- choose :: Random a => (a, a) -> Gen a
- scale :: (Int -> Int) -> Gen a -> Gen a
- resize :: Int -> Gen a -> Gen a
- getSize :: Gen Int
- sized :: (Int -> Gen a) -> Gen a
- variant :: Integral n => n -> Gen a -> Gen a
- data Gen a
- discard :: a
- newtype QC = QC Property
- optionSetToArgs :: OptionSet -> IO (Int, Args)
Documentation
testProperty :: Testable a => TestName -> a -> TestTree Source #
Create a Test for a QuickCheck Testable property
testProperties :: TestName -> [(String, Property)] -> TestTree Source #
Create a test from a list of QuickCheck properties. To be used
with allProperties. E.g.
tests :: TestTree tests = testProperties "Foo" $allProperties
newtype QuickCheckTests Source #
Number of test cases for QuickCheck to generate
Constructors
| QuickCheckTests Int |
Instances
newtype QuickCheckReplay Source #
Constructors
| QuickCheckReplay (Maybe Int) |
Instances
| IsOption QuickCheckReplay Source # | |
Defined in Test.Tasty.QuickCheck | |
newtype QuickCheckShowReplay Source #
If a test case fails unexpectedly, show the replay token
Constructors
| QuickCheckShowReplay Bool |
Instances
| IsOption QuickCheckShowReplay Source # | |
newtype QuickCheckMaxSize Source #
Size of the biggest test cases
Constructors
| QuickCheckMaxSize Int |
Instances
newtype QuickCheckMaxRatio Source #
Maximum number of of discarded tests per successful test before giving up.
Constructors
| QuickCheckMaxRatio Int |
Instances
newtype QuickCheckVerbose Source #
Show the test cases that QuickCheck generates
Constructors
| QuickCheckVerbose Bool |
Instances
| IsOption QuickCheckVerbose Source # | |
Defined in Test.Tasty.QuickCheck | |
monomorphic :: Name -> ExpQ #
Monomorphise an arbitrary property by defaulting all type variables to Integer.
For example, if f has type Ord a => [a] -> [a]$( has type monomorphic 'f)[.Integer] -> [Integer]
If you want to use monomorphic in the same file where you defined the
property, the same scoping problems pop up as in quickCheckAll:
see the note there about return [].
polyVerboseCheck :: Name -> ExpQ #
Test a polymorphic property, defaulting all type variables to Integer.
This is just a convenience function that combines verboseCheck and monomorphic.
If you want to use polyVerboseCheck in the same file where you defined the
property, the same scoping problems pop up as in quickCheckAll:
see the note there about return [].
polyQuickCheck :: Name -> ExpQ #
Test a polymorphic property, defaulting all type variables to Integer.
Invoke as $(, where polyQuickCheck 'prop)prop is a property.
Note that just evaluating quickCheck prop()!
$( means the same as
polyQuickCheck 'prop)quickCheck $(monomorphic 'prop)polyQuickCheck,
you will have to combine quickCheckWith and monomorphic yourself.
If you want to use polyQuickCheck in the same file where you defined the
property, the same scoping problems pop up as in quickCheckAll:
see the note there about return [].
pattern Failure :: Int -> Int -> Int -> Int -> QCGen -> Int -> String -> Maybe AnException -> [(String, Double)] -> String -> [String] -> Result #
A failed test run
pattern NoExpectedFailure :: Int -> [(String, Double)] -> String -> Result #
A property that should have failed did not
pattern InsufficientCoverage :: Int -> [(String, Double)] -> String -> Result #
The tests passed but a use of cover had insufficient coverage
theException :: Result -> Maybe AnException #
The exception the property threw, if any
numShrinks :: Result -> Int #
Number of successful shrinking steps performed
numShrinkTries :: Result -> Int #
Number of unsuccessful shrinking steps performed
numShrinkFinal :: Result -> Int #
Number of unsuccessful shrinking steps performed since last successful shrink
failingTestCase :: Result -> [String] #
The test case which provoked the failure
total :: NFData a => a -> Property #
Checks that a value is total, i.e., doesn't crash when evaluated.
(===) :: (Eq a, Show a) => a -> a -> Property infix 4 #
Like ==, but prints a counterexample when it fails.
(.||.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property infixr 1 #
Disjunction: p1 .||. p2 passes unless p1 and p2 simultaneously fail.
(.&&.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property infixr 1 #
Conjunction: p1 .&&. p2 passes if both p1 and p2 pass.
(.&.) :: (Testable prop1, Testable prop2) => prop1 -> prop2 -> Property infixr 1 #
Nondeterministic choice: p1 .&. p2 picks randomly one of
p1 and p2 to test. If you test the property 100 times it
makes 100 random choices.
forAllShrink :: (Show a, Testable prop) => Gen a -> (a -> [a]) -> (a -> prop) -> Property #
Like forAll, but tries to shrink the argument for failing test cases.
forAll :: (Show a, Testable prop) => Gen a -> (a -> prop) -> Property #
Explicit universal quantification: uses an explicitly given test case generator.
within :: Testable prop => Int -> prop -> Property #
Considers a property failed if it does not complete within the given number of microseconds.
(==>) :: Testable prop => Bool -> prop -> Property infixr 0 #
Implication for properties: The resulting property holds if
the first argument is False (in which case the test case is discarded),
or if the given property holds.
Arguments
| :: Testable prop | |
| => Bool |
|
| -> 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 successful test cases belong to the given class. Discarded tests (i.e. ones with a false precondition) do not affect coverage.
For example:
prop_sorted_sort :: [Int] -> Property prop_sorted_sort xs = sorted xs ==> cover (length xs > 1) 50 "non-trivial" $ sort xs === xs
>>>quickCheck prop_sorted_sort*** Insufficient coverage after 100 tests (only 24% non-trivial, not 50%).
Arguments
| :: Testable prop | |
| => Bool |
|
| -> String | Label. |
| -> prop | |
| -> Property |
Records how many test cases satisfy a given condition.
For example:
prop_sorted_sort :: [Int] -> Property prop_sorted_sort xs = sorted xs ==> classify (length xs > 1) "non-trivial" $ sort xs === xs
>>>quickCheck prop_sorted_sort+++ OK, passed 100 tests (22% non-trivial).
collect :: (Show a, Testable prop) => a -> prop -> Property #
Attaches a label to a property. This is used for reporting test case distribution.
collect x = label (show x)
For example:
prop_reverse_reverse :: [Int] -> Property
prop_reverse_reverse xs =
collect (length xs) $
reverse (reverse xs) === xs>>>quickCheck prop_reverse_reverse+++ OK, passed 100 tests: 7% 7 6% 3 5% 4 4% 6 ...
label :: Testable prop => String -> prop -> Property #
Attaches a label to a property. This is used for reporting test case distribution.
For example:
prop_reverse_reverse :: [Int] -> Property
prop_reverse_reverse xs =
label ("length of input is " ++ show (length xs)) $
reverse (reverse xs) === xs>>>quickCheck prop_reverse_reverse+++ OK, passed 100 tests: 7% length of input is 7 6% length of input is 3 5% length of input is 4 4% length of input is 6 ...
withMaxSuccess :: Testable prop => Int -> prop -> Property #
Configures how many times a property will be tested.
For example,
quickCheck (withMaxSuccess 1000 p)
will test p up to 1000 times.
again :: Testable prop => prop -> Property #
Modifies a property so that it will be tested repeatedly.
Opposite of once.
once :: Testable prop => prop -> Property #
Modifies a property so that it only will be tested once.
Opposite of again.
expectFailure :: Testable prop => prop -> Property #
Indicates that a property is supposed to fail. QuickCheck will report an error if it does not fail.
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.
whenFail :: Testable prop => IO () -> prop -> Property #
Performs an IO action after the last failure of a property.
printTestCase :: Testable prop => String -> prop -> Property #
Adds the given string to the counterexample if the property fails.
counterexample :: Testable prop => String -> prop -> Property #
Adds the given string to the counterexample if the property fails.
noShrinking :: Testable prop => prop -> Property #
Disables shrinking for a property altogether.
Arguments
| :: Testable prop | |
| => (a -> [a]) |
|
| -> a | The original argument |
| -> (a -> prop) | |
| -> Property |
Shrinks the argument to a property if it fails. Shrinking is done automatically for most types. This function is only needed when you want to override the default behavior.
mapSize :: Testable prop => (Int -> Int) -> prop -> Property #
Changes the maximum test case size for a property.
ioProperty :: Testable prop => IO prop -> Property #
Do I/O inside a property.
Warning: any random values generated inside of the argument to ioProperty
will not currently be shrunk. For best results, generate all random values
before calling ioProperty.
The type of properties.
The class of properties, i.e., types which QuickCheck knows how to test.
Typically a property will be a function returning Bool or Property.
If a property does no quantification, i.e. has no
parameters and doesn't use forAll, it will only be tested once.
This may not be what you want if your property is an IO Bool.
You can change this behaviour using the again combinator.
Minimal complete definition
Instances
| Testable Bool | |
Defined in Test.QuickCheck.Property | |
| Testable () | |
Defined in Test.QuickCheck.Property | |
| Testable Property | |
Defined in Test.QuickCheck.Property | |
| Testable Discard | |
Defined in Test.QuickCheck.Property | |
| Testable Prop | |
Defined in Test.QuickCheck.Property | |
| Testable Result | |
Defined in Test.QuickCheck.Property | |
| Testable prop => Testable (Gen prop) | |
Defined in Test.QuickCheck.Property | |
| (Arbitrary a, Show a, Testable prop) => Testable (a -> prop) | |
Defined in Test.QuickCheck.Property | |
If a property returns Discard, the current test case is discarded,
the same as if a precondition was false.
Constructors
| Discard |
applyFun3 :: Fun (a, b, c) d -> a -> b -> c -> d #
Extracts the value of a ternary function. Fn3 is the
pattern equivalent of this function.
applyFun2 :: Fun (a, b) c -> a -> b -> c #
Extracts the value of a binary function.
Fn2 is the pattern equivalent of this function.
prop_zipWith :: Fun (Int, Bool) Char -> [Int] -> [Bool] -> Bool prop_zipWith f xs ys = zipWith (applyFun2 f) xs ys == [ applyFun2 f x y | (x, y) <- zip xs ys]
applyFun :: Fun a b -> a -> b #
Extracts the value of a function.
Fn is the pattern equivalent of this function.
prop :: Fun String Integer -> Bool
prop f = applyFun f "banana" == applyFun f "monkey"
|| applyFun f "banana" == applyFun f "elephant"functionMap :: Function b => (a -> b) -> (b -> a) -> (a -> c) -> a :-> c #
pattern Fn :: forall a b. (a -> b) -> Fun a b #
A modifier for testing functions.
prop :: Fun String Integer -> Bool
prop (Fn f) = f "banana" == f "monkey"
|| f "banana" == f "elephant"pattern Fn2 :: forall a b c. (a -> b -> c) -> Fun (a, b) c #
A modifier for testing binary functions.
prop_zipWith :: Fun (Int, Bool) Char -> [Int] -> [Bool] -> Bool prop_zipWith (Fn2 f) xs ys = zipWith f xs ys == [ f x y | (x, y) <- zip xs ys]
pattern Fn3 :: forall a b c d. (a -> b -> c -> d) -> Fun (a, b, c) d #
A modifier for testing ternary functions.
The class Function a is used for random generation of showable
functions of type a -> b.
There is a default implementation for function, which you can use
if your type has structural equality. Otherwise, you can normally
use functionMap or functionShow.
Instances
Generation of random shrinkable, showable functions.
To generate random values of type Fun a bFunction a
Blind x: as x, but x does not have to be in the Show class.
Instances
| Functor Blind | |
| Enum a => Enum (Blind a) | |
| Eq a => Eq (Blind a) | |
| Integral a => Integral (Blind a) | |
Defined in Test.QuickCheck.Modifiers | |
| Num a => Num (Blind a) | |
| Ord a => Ord (Blind a) | |
Defined in Test.QuickCheck.Modifiers | |
| Real a => Real (Blind a) | |
Defined in Test.QuickCheck.Modifiers Methods toRational :: Blind a -> Rational # | |
| Show (Blind a) | |
| Arbitrary a => Arbitrary (Blind a) | |
Fixed x: as x, but will not be shrunk.
Instances
| Functor Fixed | |
| Enum a => Enum (Fixed a) | |
| Eq a => Eq (Fixed a) | |
| Integral a => Integral (Fixed a) | |
Defined in Test.QuickCheck.Modifiers | |
| Num a => Num (Fixed a) | |
| Ord a => Ord (Fixed a) | |
Defined in Test.QuickCheck.Modifiers | |
| Read a => Read (Fixed a) | |
| Real a => Real (Fixed a) | |
Defined in Test.QuickCheck.Modifiers Methods toRational :: Fixed a -> Rational # | |
| Show a => Show (Fixed a) | |
| Arbitrary a => Arbitrary (Fixed a) | |
newtype OrderedList a #
Ordered xs: guarantees that xs is ordered.
Constructors
| Ordered | |
Fields
| |
Instances
newtype NonEmptyList a #
NonEmpty xs: guarantees that xs is non-empty.
Constructors
| NonEmpty | |
Fields
| |
Instances
data InfiniteList a #
InfiniteList xs _: guarantees that xs is an infinite list.
When a counterexample is found, only prints the prefix of xs
that was used by the program.
Here is a contrived example property:
prop_take_10 :: InfiniteList Char -> Bool prop_take_10 (InfiniteList xs _) = or [ x == 'a' | x <- take 10 xs ]
In the following counterexample, the list must start with "bbbbbbbbbb" but
the remaining (infinite) part can contain anything:
>>>quickCheck prop_take_10*** Failed! Falsifiable (after 1 test and 14 shrinks): "bbbbbbbbbb" ++ ...
Constructors
| InfiniteList | |
Fields
| |
Instances
| Show a => Show (InfiniteList a) | |
Defined in Test.QuickCheck.Modifiers Methods showsPrec :: Int -> InfiniteList a -> ShowS # show :: InfiniteList a -> String # showList :: [InfiniteList a] -> ShowS # | |
| Arbitrary a => Arbitrary (InfiniteList a) | |
Defined in Test.QuickCheck.Modifiers | |
Positive x: guarantees that x > 0.
Constructors
| Positive | |
Fields
| |
Instances
| Functor Positive | |
| Enum a => Enum (Positive a) | |
Defined in Test.QuickCheck.Modifiers Methods succ :: Positive a -> Positive a # pred :: Positive a -> Positive a # fromEnum :: Positive a -> Int # enumFrom :: Positive a -> [Positive a] # enumFromThen :: Positive a -> Positive a -> [Positive a] # enumFromTo :: Positive a -> Positive a -> [Positive a] # enumFromThenTo :: Positive a -> Positive a -> Positive a -> [Positive a] # | |
| Eq a => Eq (Positive a) | |
| Ord a => Ord (Positive a) | |
Defined in Test.QuickCheck.Modifiers | |
| Read a => Read (Positive a) | |
| Show a => Show (Positive a) | |
| (Num a, Ord a, Arbitrary a) => Arbitrary (Positive a) | |
NonZero x: guarantees that x /= 0.
Constructors
| NonZero | |
Fields
| |
Instances
| Functor NonZero | |
| Enum a => Enum (NonZero a) | |
Defined in Test.QuickCheck.Modifiers Methods succ :: NonZero a -> NonZero a # pred :: NonZero a -> NonZero a # fromEnum :: NonZero a -> Int # enumFrom :: NonZero a -> [NonZero a] # enumFromThen :: NonZero a -> NonZero a -> [NonZero a] # enumFromTo :: NonZero a -> NonZero a -> [NonZero a] # enumFromThenTo :: NonZero a -> NonZero a -> NonZero a -> [NonZero a] # | |
| Eq a => Eq (NonZero a) | |
| Ord a => Ord (NonZero a) | |
| Read a => Read (NonZero a) | |
| Show a => Show (NonZero a) | |
| (Num a, Eq a, Arbitrary a) => Arbitrary (NonZero a) | |
newtype NonNegative a #
NonNegative x: guarantees that x >= 0.
Constructors
| NonNegative | |
Fields
| |
Instances
Large x: by default, QuickCheck generates Ints drawn from a small
range. Large Int gives you values drawn from the entire range instead.
Instances
| Functor Large | |
| Enum a => Enum (Large a) | |
| Eq a => Eq (Large a) | |
| Integral a => Integral (Large a) | |
Defined in Test.QuickCheck.Modifiers | |
| Num a => Num (Large a) | |
| Ord a => Ord (Large a) | |
Defined in Test.QuickCheck.Modifiers | |
| Read a => Read (Large a) | |
| Real a => Real (Large a) | |
Defined in Test.QuickCheck.Modifiers Methods toRational :: Large a -> Rational # | |
| Show a => Show (Large a) | |
| Ix a => Ix (Large a) | |
Defined in Test.QuickCheck.Modifiers | |
| (Integral a, Bounded a) => Arbitrary (Large a) | |
Small x: generates values of x drawn from a small range.
The opposite of Large.
Instances
| Functor Small | |
| Enum a => Enum (Small a) | |
| Eq a => Eq (Small a) | |
| Integral a => Integral (Small a) | |
Defined in Test.QuickCheck.Modifiers | |
| Num a => Num (Small a) | |
| Ord a => Ord (Small a) | |
Defined in Test.QuickCheck.Modifiers | |
| Read a => Read (Small a) | |
| Real a => Real (Small a) | |
Defined in Test.QuickCheck.Modifiers Methods toRational :: Small a -> Rational # | |
| Show a => Show (Small a) | |
| Ix a => Ix (Small a) | |
Defined in Test.QuickCheck.Modifiers | |
| Integral a => Arbitrary (Small a) | |
Shrink2 x: allows 2 shrinking steps at the same time when shrinking x
Constructors
| Shrink2 | |
Fields
| |
Instances
Smart _ x: tries a different order when shrinking.
Shrinking _ x: allows for maintaining a state during shrinking.
Constructors
| Shrinking s a |
class ShrinkState s a where #
Minimal complete definition
newtype ASCIIString #
ASCIIString: generates an ASCII string.
Constructors
| ASCIIString | |
Fields | |
Instances
| Eq ASCIIString | |
Defined in Test.QuickCheck.Modifiers | |
| Ord ASCIIString | |
Defined in Test.QuickCheck.Modifiers Methods compare :: ASCIIString -> ASCIIString -> Ordering # (<) :: ASCIIString -> ASCIIString -> Bool # (<=) :: ASCIIString -> ASCIIString -> Bool # (>) :: ASCIIString -> ASCIIString -> Bool # (>=) :: ASCIIString -> ASCIIString -> Bool # max :: ASCIIString -> ASCIIString -> ASCIIString # min :: ASCIIString -> ASCIIString -> ASCIIString # | |
| Read ASCIIString | |
Defined in Test.QuickCheck.Modifiers Methods readsPrec :: Int -> ReadS ASCIIString # readList :: ReadS [ASCIIString] # readPrec :: ReadPrec ASCIIString # readListPrec :: ReadPrec [ASCIIString] # | |
| Show ASCIIString | |
Defined in Test.QuickCheck.Modifiers Methods showsPrec :: Int -> ASCIIString -> ShowS # show :: ASCIIString -> String # showList :: [ASCIIString] -> ShowS # | |
| Arbitrary ASCIIString | |
Defined in Test.QuickCheck.Modifiers | |
newtype UnicodeString #
UnicodeString: generates a unicode String.
The string will not contain surrogate pairs.
Constructors
| UnicodeString | |
Fields | |
Instances
| Eq UnicodeString | |
Defined in Test.QuickCheck.Modifiers Methods (==) :: UnicodeString -> UnicodeString -> Bool # (/=) :: UnicodeString -> UnicodeString -> Bool # | |
| Ord UnicodeString | |
Defined in Test.QuickCheck.Modifiers Methods compare :: UnicodeString -> UnicodeString -> Ordering # (<) :: UnicodeString -> UnicodeString -> Bool # (<=) :: UnicodeString -> UnicodeString -> Bool # (>) :: UnicodeString -> UnicodeString -> Bool # (>=) :: UnicodeString -> UnicodeString -> Bool # max :: UnicodeString -> UnicodeString -> UnicodeString # min :: UnicodeString -> UnicodeString -> UnicodeString # | |
| Read UnicodeString | |
Defined in Test.QuickCheck.Modifiers Methods readsPrec :: Int -> ReadS UnicodeString # readList :: ReadS [UnicodeString] # | |
| Show UnicodeString | |
Defined in Test.QuickCheck.Modifiers Methods showsPrec :: Int -> UnicodeString -> ShowS # show :: UnicodeString -> String # showList :: [UnicodeString] -> ShowS # | |
| Arbitrary UnicodeString | |
Defined in Test.QuickCheck.Modifiers | |
newtype PrintableString #
PrintableString: generates a printable unicode String.
The string will not contain surrogate pairs.
Constructors
| PrintableString | |
Fields | |
Instances
infiniteList :: Arbitrary a => Gen [a] #
Generates an infinite list.
orderedList :: (Ord a, Arbitrary a) => Gen [a] #
Generates an ordered list.
coarbitraryEnum :: Enum a => a -> Gen b -> Gen b #
A coarbitrary implementation for enums.
coarbitraryShow :: Show a => a -> Gen b -> Gen b #
coarbitrary helper for lazy people :-).
coarbitraryReal :: Real a => a -> Gen b -> Gen b #
A coarbitrary implementation for real numbers.
coarbitraryIntegral :: Integral a => a -> Gen b -> Gen b #
A coarbitrary implementation for integral numbers.
(><) :: (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.
genericCoarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b #
Generic CoArbitrary implementation.
shrinkRealFrac :: RealFrac a => a -> [a] #
Shrink a fraction.
shrinkIntegral :: Integral a => a -> [a] #
Shrink an integral number.
shrinkMapBy :: (a -> b) -> (b -> a) -> (a -> [a]) -> b -> [b] #
Non-overloaded version of shrinkMap.
shrinkMap :: Arbitrary a => (a -> b) -> (b -> a) -> b -> [b] #
Map a shrink function to another domain. This is handy if your data type has special invariants, but is almost isomorphic to some other type.
shrinkOrderedList :: (Ord a, Arbitrary a) => [a] -> [[a]] shrinkOrderedList = shrinkMap sort id shrinkSet :: (Ord a, Arbitrary a) => Set a -> Set [a] shrinkSet = shrinkMap fromList toList
shrinkNothing :: a -> [a] #
Returns no shrinking alternatives.
arbitraryPrintableChar :: Gen Char #
Generates a printable Unicode character.
arbitraryASCIIChar :: Gen Char #
Generates a random ASCII character (0-127).
arbitraryUnicodeChar :: Gen Char #
Generates any Unicode character (but not a surrogate)
arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen a #
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.
arbitraryBoundedEnum :: (Bounded a, Enum a) => Gen a #
Generates an element of a bounded enumeration.
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.
arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a #
Generates an integral number. The number is chosen uniformly from
the entire range of the type. You may want to use
arbitrarySizedBoundedIntegral instead.
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.
arbitrarySizedNatural :: Integral a => Gen a #
Generates a natural number. The number's maximum value depends on the size parameter.
arbitrarySizedIntegral :: Integral a => Gen a #
Generates an integral number. The number can be positive or negative and its maximum absolute value depends on the size parameter.
applyArbitrary4 :: (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => (a -> b -> c -> d -> r) -> Gen r #
Apply a function of arity 4 to random arguments.
applyArbitrary3 :: (Arbitrary a, Arbitrary b, Arbitrary c) => (a -> b -> c -> r) -> Gen r #
Apply a ternary function to random arguments.
applyArbitrary2 :: (Arbitrary a, Arbitrary b) => (a -> b -> r) -> Gen r #
Apply a binary function to random arguments.
shrinkList :: (a -> [a]) -> [a] -> [[a]] #
Shrink a list of values given a shrinking function for individual values.
recursivelyShrink :: (Generic a, RecursivelyShrink (Rep a)) => a -> [a] #
Recursively shrink all immediate subterms.
genericShrink :: (Generic a, RecursivelyShrink (Rep a), GSubterms (Rep a) a) => a -> [a] #
Shrink a term to any of its immediate subterms, and also recursively shrink all subterms.
shrink2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => f a b -> [f a b] #
arbitrary2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => Gen (f a b) #
shrink1 :: (Arbitrary1 f, Arbitrary a) => f a -> [f a] #
arbitrary1 :: (Arbitrary1 f, Arbitrary a) => Gen (f a) #
Random generation and shrinking of values.
QuickCheck provides Arbitrary instances for most types in base,
except those which incur extra dependencies.
For a wider range of Arbitrary instances see the
quickcheck-instances
package.
Minimal complete definition
Methods
A generator for values of the given type.
It is worth spending time thinking about what sort of test data
you want - good generators are often the difference between
finding bugs and not finding them. You can use sample,
label and classify to check the quality of your test data.
There is no generic arbitrary implementation included because we don't
know how to make a high-quality one. If you want one, consider using the
testing-feat or
generic-random packages.
The QuickCheck manual goes into detail on how to write good generators. Make sure to look at it, especially if your type is recursive!
Produces a (possibly) empty list of all the possible immediate shrinks of the given value.
The default implementation returns the empty list, so will not try to
shrink the value. If your data type has no special invariants, you can
enable shrinking by defining shrink = , but by customising
the behaviour of genericShrinkshrink you can often get simpler counterexamples.
Most implementations of shrink should try at least three things:
- Shrink a term to any of its immediate subterms.
You can use
subtermsto do this. - Recursively apply
shrinkto all immediate subterms. You can userecursivelyShrinkto do this. - Type-specific shrinkings such as replacing a constructor by a simpler constructor.
For example, suppose we have the following implementation of binary trees:
data Tree a = Nil | Branch a (Tree a) (Tree a)
We can then define shrink as follows:
shrink Nil = [] shrink (Branch x l r) = -- shrink Branch to Nil [Nil] ++ -- shrink to subterms [l, r] ++ -- recursively shrink subterms [Branch x' l' r' | (x', l', r') <- shrink (x, l, r)]
There are a couple of subtleties here:
- QuickCheck tries the shrinking candidates in the order they
appear in the list, so we put more aggressive shrinking steps
(such as replacing the whole tree by
Nil) before smaller ones (such as recursively shrinking the subtrees). - It is tempting to write the last line as
[Branch x' l' r' | x' <- shrink x, l' <- shrink l, r' <- shrink r]but this is the wrong thing! It will force QuickCheck to shrinkx,landrin tandem, and shrinking will stop once one of the three is fully shrunk.
There is a fair bit of boilerplate in the code above.
We can avoid it with the help of some generic functions.
The function genericShrink tries shrinking a term to all of its
subterms and, failing that, recursively shrinks the subterms.
Using it, we can define shrink as:
shrink x = shrinkToNil x ++ genericShrink x
where
shrinkToNil Nil = []
shrinkToNil (Branch _ l r) = [Nil]genericShrink is a combination of subterms, which shrinks
a term to any of its subterms, and recursivelyShrink, which shrinks
all subterms of a term. These may be useful if you need a bit more
control over shrinking than genericShrink gives you.
A final gotcha: we cannot define shrink as simply shrink x = Nil:genericShrink xNil to Nil, and shrinking will go into an
infinite loop.
If all this leaves you bewildered, you might try shrink = genericShrinkGeneric for your type. However, if your data type has any
special invariants, you will need to check that genericShrink can't break those invariants.
Instances
class Arbitrary1 (f :: * -> *) where #
Lifting of the Arbitrary class to unary type constructors.
Minimal complete definition
Instances
class Arbitrary2 (f :: * -> * -> *) where #
Lifting of the Arbitrary class to binary type constructors.
Minimal complete definition
Methods
liftArbitrary2 :: Gen a -> Gen b -> Gen (f a b) #
liftShrink2 :: (a -> [a]) -> (b -> [b]) -> f a b -> [f a b] #
Instances
| Arbitrary2 Either | |
Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Either a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Either a b -> [Either a b] # | |
| Arbitrary2 (,) | |
Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (a, b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> (a, b) -> [(a, b)] # | |
| Arbitrary2 (Const :: * -> * -> *) | |
Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Const a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Const a b -> [Const a b] # | |
| Arbitrary2 (Constant :: * -> * -> *) | |
Defined in Test.QuickCheck.Arbitrary Methods liftArbitrary2 :: Gen a -> Gen b -> Gen (Constant a b) # liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Constant a b -> [Constant a b] # | |
class CoArbitrary a where #
Used for random generation of functions.
If you are using a recent GHC, there is a default definition of
coarbitrary using genericCoarbitrary, so if your type has a
Generic instance it's enough to say
instance CoArbitrary MyType
You should only use genericCoarbitrary for data types where
equality is structural, i.e. if you can't have two different
representations of the same value. An example where it's not
safe is sets implemented using binary search trees: the same
set can be represented as several different trees.
Here you would have to explicitly define
coarbitrary s = coarbitrary (toList s).
Methods
coarbitrary :: a -> Gen b -> Gen b #
Used to generate a function of type a -> b.
The first argument is a value, the second a generator.
You should use variant to perturb the random generator;
the goal is that different values for the first argument will
lead to different calls to variant. An example will help:
instance CoArbitrary a => CoArbitrary [a] where coarbitrary [] =variant0 coarbitrary (x:xs) =variant1 . coarbitrary (x,xs)
Instances
infiniteListOf :: Gen a -> Gen [a] #
Generates an infinite list.
Generates a non-empty list of random length. The maximum length depends on the size parameter.
Generates a list of random length. The maximum length depends on the size parameter.
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.
frequency :: [(Int, Gen a)] -> Gen a #
Chooses one of the given generators, with a weighted random distribution. The input list must be non-empty.
Randomly uses one of the given generators. The input list must be non-empty.
suchThatMaybe :: Gen a -> (a -> Bool) -> Gen (Maybe a) #
Tries to generate a value that satisfies a predicate.
If it fails to do so after enough attempts, returns Nothing.
suchThatMap :: Gen a -> (a -> Maybe b) -> Gen b #
Generates a value for which the given function returns a Just, and then
applies the function.
Run a generator. The size passed to the generator is always 30;
if you want another size then you should explicitly use resize.
scale :: (Int -> Int) -> Gen a -> Gen a #
Adjust the size parameter, by transforming it with the given function.
resize :: Int -> Gen a -> Gen a #
Overrides the size parameter. Returns a generator which uses the given size instead of the runtime-size parameter.
Generates the size parameter. Used to construct generators that depend on the size parameter.
For example, listOf, which uses the size parameter as an upper bound on
length of lists it generates, can be defined like this:
listOf :: Gen a -> Gen [a] listOf gen = do n <- getSize k <- choose (0,n) vectorOf k gen
You can also do this using sized.
sized :: (Int -> Gen a) -> Gen a #
Used to construct generators that depend on the size parameter.
For example, listOf, which uses the size parameter as an upper bound on
length of lists it generates, can be defined like this:
listOf :: Gen a -> Gen [a]
listOf gen = sized $ \n ->
do k <- choose (0,n)
vectorOf k genYou can also do this using getSize.
A generator for values of type a.
The third-party package
QuickCheck-GenT
provides a monad transformer version of GenT.
Instances
| Monad Gen | |
| Functor Gen | |
| Applicative Gen | |
| Testable prop => Testable (Gen prop) | |
Defined in Test.QuickCheck.Property | |
A special exception that makes QuickCheck discard the test case.
Normally you should use ==>, but if for some reason this isn't
possible (e.g. you are deep inside a generator), use discard
instead.
Internal
If you are building a test suite, you don't need these functions.
They may be used by other tasty add-on packages (such as tasty-hspec).