QuickCheck-2.11.3: Automatic testing of Haskell programs

Safe HaskellTrustworthy
LanguageHaskell98

Test.QuickCheck.Arbitrary

Contents

Description

Type classes for random generation of values.

Synopsis

Arbitrary and CoArbitrary classes

class Arbitrary a where Source #

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

arbitrary

Methods

arbitrary :: Gen a Source #

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!

shrink :: a -> [a] Source #

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 = genericShrink, but by customising the behaviour of shrink you can often get simpler counterexamples.

Most implementations of shrink should try at least three things:

  1. Shrink a term to any of its immediate subterms. You can use subterms to do this.
  2. Recursively apply shrink to all immediate subterms. You can use recursivelyShrink to do this.
  3. 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 shrink x, l and r in 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 x as this shrinks Nil to Nil, and shrinking will go into an infinite loop.

If all this leaves you bewildered, you might try shrink = genericShrink to begin with, after deriving Generic 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

Arbitrary Bool Source # 
Arbitrary Char Source # 
Arbitrary Double Source # 
Arbitrary Float Source # 
Arbitrary Int Source # 
Arbitrary Int8 Source # 
Arbitrary Int16 Source # 
Arbitrary Int32 Source # 
Arbitrary Int64 Source # 
Arbitrary Integer Source # 
Arbitrary Ordering Source # 
Arbitrary Word Source # 
Arbitrary Word8 Source # 
Arbitrary Word16 Source # 
Arbitrary Word32 Source # 
Arbitrary Word64 Source # 
Arbitrary () Source # 

Methods

arbitrary :: Gen () Source #

shrink :: () -> [()] Source #

Arbitrary Version Source #

Generates Version with non-empty non-negative versionBranch, and empty versionTags

Arbitrary ExitCode Source # 
Arbitrary All Source # 
Arbitrary Any Source # 
Arbitrary CChar Source # 
Arbitrary CSChar Source # 
Arbitrary CUChar Source # 
Arbitrary CShort Source # 
Arbitrary CUShort Source # 
Arbitrary CInt Source # 
Arbitrary CUInt Source # 
Arbitrary CLong Source # 
Arbitrary CULong Source # 
Arbitrary CLLong Source # 
Arbitrary CULLong Source # 
Arbitrary CFloat Source # 
Arbitrary CDouble Source # 
Arbitrary CPtrdiff Source # 
Arbitrary CSize Source # 
Arbitrary CWchar Source # 
Arbitrary CSigAtomic Source # 
Arbitrary CClock Source # 
Arbitrary CTime Source # 
Arbitrary CUSeconds Source # 
Arbitrary CSUSeconds Source # 
Arbitrary CIntPtr Source # 
Arbitrary CUIntPtr Source # 
Arbitrary CIntMax Source # 
Arbitrary CUIntMax Source # 
Arbitrary IntSet Source # 
Arbitrary QCGen Source # 
Arbitrary OrdC Source # 
Arbitrary OrdB Source # 
Arbitrary OrdA Source # 
Arbitrary C Source # 

Methods

arbitrary :: Gen C Source #

shrink :: C -> [C] Source #

Arbitrary B Source # 

Methods

arbitrary :: Gen B Source #

shrink :: B -> [B] Source #

Arbitrary A Source # 

Methods

arbitrary :: Gen A Source #

shrink :: A -> [A] Source #

Arbitrary PrintableString Source # 
Arbitrary UnicodeString Source # 
Arbitrary ASCIIString Source # 
Arbitrary a => Arbitrary [a] Source # 

Methods

arbitrary :: Gen [a] Source #

shrink :: [a] -> [[a]] Source #

Arbitrary a => Arbitrary (Maybe a) Source # 

Methods

arbitrary :: Gen (Maybe a) Source #

shrink :: Maybe a -> [Maybe a] Source #

Integral a => Arbitrary (Ratio a) Source # 

Methods

arbitrary :: Gen (Ratio a) Source #

shrink :: Ratio a -> [Ratio a] Source #

(RealFloat a, Arbitrary a) => Arbitrary (Complex a) Source # 
HasResolution a => Arbitrary (Fixed a) Source # 

Methods

arbitrary :: Gen (Fixed a) Source #

shrink :: Fixed a -> [Fixed a] Source #

Arbitrary a => Arbitrary (ZipList a) Source # 
Arbitrary a => Arbitrary (Identity a) Source # 
Arbitrary a => Arbitrary (Dual a) Source # 

Methods

arbitrary :: Gen (Dual a) Source #

shrink :: Dual a -> [Dual a] Source #

(Arbitrary a, CoArbitrary a) => Arbitrary (Endo a) Source # 

Methods

arbitrary :: Gen (Endo a) Source #

shrink :: Endo a -> [Endo a] Source #

Arbitrary a => Arbitrary (Sum a) Source # 

Methods

arbitrary :: Gen (Sum a) Source #

shrink :: Sum a -> [Sum a] Source #

Arbitrary a => Arbitrary (Product a) Source # 
Arbitrary a => Arbitrary (First a) Source # 

Methods

arbitrary :: Gen (First a) Source #

shrink :: First a -> [First a] Source #

Arbitrary a => Arbitrary (Last a) Source # 

Methods

arbitrary :: Gen (Last a) Source #

shrink :: Last a -> [Last a] Source #

Arbitrary a => Arbitrary (IntMap a) Source # 

Methods

arbitrary :: Gen (IntMap a) Source #

shrink :: IntMap a -> [IntMap a] Source #

Arbitrary a => Arbitrary (Seq a) Source # 

Methods

arbitrary :: Gen (Seq a) Source #

shrink :: Seq a -> [Seq a] Source #

(Ord a, Arbitrary a) => Arbitrary (Set a) Source # 

Methods

arbitrary :: Gen (Set a) Source #

shrink :: Set a -> [Set a] Source #

Arbitrary a => Arbitrary (Smart a) Source # 

Methods

arbitrary :: Gen (Smart a) Source #

shrink :: Smart a -> [Smart a] Source #

Arbitrary a => Arbitrary (Shrink2 a) Source # 
Integral a => Arbitrary (Small a) Source # 

Methods

arbitrary :: Gen (Small a) Source #

shrink :: Small a -> [Small a] Source #

(Integral a, Bounded a) => Arbitrary (Large a) Source # 

Methods

arbitrary :: Gen (Large a) Source #

shrink :: Large a -> [Large a] Source #

(Num a, Ord a, Arbitrary a) => Arbitrary (NonNegative a) Source # 
(Num a, Eq a, Arbitrary a) => Arbitrary (NonZero a) Source # 
(Num a, Ord a, Arbitrary a) => Arbitrary (Positive a) Source # 
Arbitrary a => Arbitrary (InfiniteList a) Source # 
Arbitrary a => Arbitrary (NonEmptyList a) Source # 
(Ord a, Arbitrary a) => Arbitrary (OrderedList a) Source # 
Arbitrary a => Arbitrary (Fixed a) Source # 

Methods

arbitrary :: Gen (Fixed a) Source #

shrink :: Fixed a -> [Fixed a] Source #

Arbitrary a => Arbitrary (Blind a) Source # 

Methods

arbitrary :: Gen (Blind a) Source #

shrink :: Blind a -> [Blind a] Source #

(CoArbitrary a, Arbitrary b) => Arbitrary (a -> b) Source # 

Methods

arbitrary :: Gen (a -> b) Source #

shrink :: (a -> b) -> [a -> b] Source #

(Arbitrary a, Arbitrary b) => Arbitrary (Either a b) Source # 

Methods

arbitrary :: Gen (Either a b) Source #

shrink :: Either a b -> [Either a b] Source #

(Arbitrary a, Arbitrary b) => Arbitrary (a, b) Source # 

Methods

arbitrary :: Gen (a, b) Source #

shrink :: (a, b) -> [(a, b)] Source #

Arbitrary (m a) => Arbitrary (WrappedMonad m a) Source # 
(Ord k, Arbitrary k, Arbitrary v) => Arbitrary (Map k v) Source # 

Methods

arbitrary :: Gen (Map k v) Source #

shrink :: Map k v -> [Map k v] Source #

(Arbitrary a, ShrinkState s a) => Arbitrary (Shrinking s a) Source # 

Methods

arbitrary :: Gen (Shrinking s a) Source #

shrink :: Shrinking s a -> [Shrinking s a] Source #

(Function a, CoArbitrary a, Arbitrary b) => Arbitrary (Fun a b) Source # 

Methods

arbitrary :: Gen (Fun a b) Source #

shrink :: Fun a b -> [Fun a b] Source #

(Function a, CoArbitrary a, Arbitrary b) => Arbitrary ((:->) a b) Source # 

Methods

arbitrary :: Gen (a :-> b) Source #

shrink :: (a :-> b) -> [a :-> b] Source #

(Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (a, b, c) Source # 

Methods

arbitrary :: Gen (a, b, c) Source #

shrink :: (a, b, c) -> [(a, b, c)] Source #

Arbitrary (a b c) => Arbitrary (WrappedArrow a b c) Source # 

Methods

arbitrary :: Gen (WrappedArrow a b c) Source #

shrink :: WrappedArrow a b c -> [WrappedArrow a b c] Source #

Arbitrary a => Arbitrary (Const k a b) Source # 

Methods

arbitrary :: Gen (Const k a b) Source #

shrink :: Const k a b -> [Const k a b] Source #

Arbitrary (f a) => Arbitrary (Alt k f a) Source # 

Methods

arbitrary :: Gen (Alt k f a) Source #

shrink :: Alt k f a -> [Alt k f a] Source #

Arbitrary a => Arbitrary (Constant k a b) Source # 

Methods

arbitrary :: Gen (Constant k a b) Source #

shrink :: Constant k a b -> [Constant k a b] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => Arbitrary (a, b, c, d) Source # 

Methods

arbitrary :: Gen (a, b, c, d) Source #

shrink :: (a, b, c, d) -> [(a, b, c, d)] Source #

(Arbitrary1 f, Arbitrary1 g, Arbitrary a) => Arbitrary (Product * f g a) Source # 

Methods

arbitrary :: Gen (Product * f g a) Source #

shrink :: Product * f g a -> [Product * f g a] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e) => Arbitrary (a, b, c, d, e) Source # 

Methods

arbitrary :: Gen (a, b, c, d, e) Source #

shrink :: (a, b, c, d, e) -> [(a, b, c, d, e)] Source #

(Arbitrary1 f, Arbitrary1 g, Arbitrary a) => Arbitrary (Compose * * f g a) Source # 

Methods

arbitrary :: Gen (Compose * * f g a) Source #

shrink :: Compose * * f g a -> [Compose * * f g a] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f) => Arbitrary (a, b, c, d, e, f) Source # 

Methods

arbitrary :: Gen (a, b, c, d, e, f) Source #

shrink :: (a, b, c, d, e, f) -> [(a, b, c, d, e, f)] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g) => Arbitrary (a, b, c, d, e, f, g) Source # 

Methods

arbitrary :: Gen (a, b, c, d, e, f, g) Source #

shrink :: (a, b, c, d, e, f, g) -> [(a, b, c, d, e, f, g)] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g, Arbitrary h) => Arbitrary (a, b, c, d, e, f, g, h) Source # 

Methods

arbitrary :: Gen (a, b, c, d, e, f, g, h) Source #

shrink :: (a, b, c, d, e, f, g, h) -> [(a, b, c, d, e, f, g, h)] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g, Arbitrary h, Arbitrary i) => Arbitrary (a, b, c, d, e, f, g, h, i) Source # 

Methods

arbitrary :: Gen (a, b, c, d, e, f, g, h, i) Source #

shrink :: (a, b, c, d, e, f, g, h, i) -> [(a, b, c, d, e, f, g, h, i)] Source #

(Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d, Arbitrary e, Arbitrary f, Arbitrary g, Arbitrary h, Arbitrary i, Arbitrary j) => Arbitrary (a, b, c, d, e, f, g, h, i, j) Source # 

Methods

arbitrary :: Gen (a, b, c, d, e, f, g, h, i, j) Source #

shrink :: (a, b, c, d, e, f, g, h, i, j) -> [(a, b, c, d, e, f, g, h, i, j)] Source #

class CoArbitrary a where Source #

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 Source #

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 []     = variant 0
  coarbitrary (x:xs) = variant 1 . coarbitrary (x,xs)

coarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b Source #

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 []     = variant 0
  coarbitrary (x:xs) = variant 1 . coarbitrary (x,xs)

Instances

CoArbitrary Bool Source # 

Methods

coarbitrary :: Bool -> Gen b -> Gen b Source #

CoArbitrary Char Source # 

Methods

coarbitrary :: Char -> Gen b -> Gen b Source #

CoArbitrary Double Source # 

Methods

coarbitrary :: Double -> Gen b -> Gen b Source #

CoArbitrary Float Source # 

Methods

coarbitrary :: Float -> Gen b -> Gen b Source #

CoArbitrary Int Source # 

Methods

coarbitrary :: Int -> Gen b -> Gen b Source #

CoArbitrary Int8 Source # 

Methods

coarbitrary :: Int8 -> Gen b -> Gen b Source #

CoArbitrary Int16 Source # 

Methods

coarbitrary :: Int16 -> Gen b -> Gen b Source #

CoArbitrary Int32 Source # 

Methods

coarbitrary :: Int32 -> Gen b -> Gen b Source #

CoArbitrary Int64 Source # 

Methods

coarbitrary :: Int64 -> Gen b -> Gen b Source #

CoArbitrary Integer Source # 

Methods

coarbitrary :: Integer -> Gen b -> Gen b Source #

CoArbitrary Ordering Source # 

Methods

coarbitrary :: Ordering -> Gen b -> Gen b Source #

CoArbitrary Word Source # 

Methods

coarbitrary :: Word -> Gen b -> Gen b Source #

CoArbitrary Word8 Source # 

Methods

coarbitrary :: Word8 -> Gen b -> Gen b Source #

CoArbitrary Word16 Source # 

Methods

coarbitrary :: Word16 -> Gen b -> Gen b Source #

CoArbitrary Word32 Source # 

Methods

coarbitrary :: Word32 -> Gen b -> Gen b Source #

CoArbitrary Word64 Source # 

Methods

coarbitrary :: Word64 -> Gen b -> Gen b Source #

CoArbitrary () Source # 

Methods

coarbitrary :: () -> Gen b -> Gen b Source #

CoArbitrary Version Source # 

Methods

coarbitrary :: Version -> Gen b -> Gen b Source #

CoArbitrary All Source # 

Methods

coarbitrary :: All -> Gen b -> Gen b Source #

CoArbitrary Any Source # 

Methods

coarbitrary :: Any -> Gen b -> Gen b Source #

CoArbitrary IntSet Source # 

Methods

coarbitrary :: IntSet -> Gen b -> Gen b Source #

CoArbitrary OrdC Source # 

Methods

coarbitrary :: OrdC -> Gen b -> Gen b Source #

CoArbitrary OrdB Source # 

Methods

coarbitrary :: OrdB -> Gen b -> Gen b Source #

CoArbitrary OrdA Source # 

Methods

coarbitrary :: OrdA -> Gen b -> Gen b Source #

CoArbitrary C Source # 

Methods

coarbitrary :: C -> Gen b -> Gen b Source #

CoArbitrary B Source # 

Methods

coarbitrary :: B -> Gen b -> Gen b Source #

CoArbitrary A Source # 

Methods

coarbitrary :: A -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary [a] Source # 

Methods

coarbitrary :: [a] -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Maybe a) Source # 

Methods

coarbitrary :: Maybe a -> Gen b -> Gen b Source #

(Integral a, CoArbitrary a) => CoArbitrary (Ratio a) Source # 

Methods

coarbitrary :: Ratio a -> Gen b -> Gen b Source #

(RealFloat a, CoArbitrary a) => CoArbitrary (Complex a) Source # 

Methods

coarbitrary :: Complex a -> Gen b -> Gen b Source #

HasResolution a => CoArbitrary (Fixed a) Source # 

Methods

coarbitrary :: Fixed a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (ZipList a) Source # 

Methods

coarbitrary :: ZipList a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Identity a) Source # 

Methods

coarbitrary :: Identity a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Dual a) Source # 

Methods

coarbitrary :: Dual a -> Gen b -> Gen b Source #

(Arbitrary a, CoArbitrary a) => CoArbitrary (Endo a) Source # 

Methods

coarbitrary :: Endo a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Sum a) Source # 

Methods

coarbitrary :: Sum a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Product a) Source # 

Methods

coarbitrary :: Product a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (First a) Source # 

Methods

coarbitrary :: First a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Last a) Source # 

Methods

coarbitrary :: Last a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (IntMap a) Source # 

Methods

coarbitrary :: IntMap a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Seq a) Source # 

Methods

coarbitrary :: Seq a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Set a) Source # 

Methods

coarbitrary :: Set a -> Gen b -> Gen b Source #

(Arbitrary a, CoArbitrary b) => CoArbitrary (a -> b) Source # 

Methods

coarbitrary :: (a -> b) -> Gen b -> Gen b Source #

(CoArbitrary a, CoArbitrary b) => CoArbitrary (Either a b) Source # 

Methods

coarbitrary :: Either a b -> Gen b -> Gen b Source #

(CoArbitrary a, CoArbitrary b) => CoArbitrary (a, b) Source # 

Methods

coarbitrary :: (a, b) -> Gen b -> Gen b Source #

(CoArbitrary k, CoArbitrary v) => CoArbitrary (Map k v) Source # 

Methods

coarbitrary :: Map k v -> Gen b -> Gen b Source #

(CoArbitrary a, CoArbitrary b, CoArbitrary c) => CoArbitrary (a, b, c) Source # 

Methods

coarbitrary :: (a, b, c) -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Const k a b) Source # 

Methods

coarbitrary :: Const k a b -> Gen b -> Gen b Source #

CoArbitrary (f a) => CoArbitrary (Alt k f a) Source # 

Methods

coarbitrary :: Alt k f a -> Gen b -> Gen b Source #

CoArbitrary a => CoArbitrary (Constant k a b) Source # 

Methods

coarbitrary :: Constant k a b -> Gen b -> Gen b Source #

(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d) => CoArbitrary (a, b, c, d) Source # 

Methods

coarbitrary :: (a, b, c, d) -> Gen b -> Gen b Source #

(CoArbitrary a, CoArbitrary b, CoArbitrary c, CoArbitrary d, CoArbitrary e) => CoArbitrary (a, b, c, d, e) Source # 

Methods

coarbitrary :: (a, b, c, d, e) -> Gen b -> Gen b Source #

Unary and Binary classes

class Arbitrary1 f where Source #

Lifting of the Arbitrary class to unary type constructors.

Minimal complete definition

liftArbitrary

Methods

liftArbitrary :: Gen a -> Gen (f a) Source #

liftShrink :: (a -> [a]) -> f a -> [f a] Source #

Instances

Arbitrary1 [] Source # 

Methods

liftArbitrary :: Gen a -> Gen [a] Source #

liftShrink :: (a -> [a]) -> [a] -> [[a]] Source #

Arbitrary1 Maybe Source # 

Methods

liftArbitrary :: Gen a -> Gen (Maybe a) Source #

liftShrink :: (a -> [a]) -> Maybe a -> [Maybe a] Source #

Arbitrary1 ZipList Source # 

Methods

liftArbitrary :: Gen a -> Gen (ZipList a) Source #

liftShrink :: (a -> [a]) -> ZipList a -> [ZipList a] Source #

Arbitrary1 Identity Source # 

Methods

liftArbitrary :: Gen a -> Gen (Identity a) Source #

liftShrink :: (a -> [a]) -> Identity a -> [Identity a] Source #

Arbitrary1 IntMap Source # 

Methods

liftArbitrary :: Gen a -> Gen (IntMap a) Source #

liftShrink :: (a -> [a]) -> IntMap a -> [IntMap a] Source #

Arbitrary1 Seq Source # 

Methods

liftArbitrary :: Gen a -> Gen (Seq a) Source #

liftShrink :: (a -> [a]) -> Seq a -> [Seq a] Source #

Arbitrary a => Arbitrary1 (Either a) Source # 

Methods

liftArbitrary :: Gen a -> Gen (Either a a) Source #

liftShrink :: (a -> [a]) -> Either a a -> [Either a a] Source #

Arbitrary a => Arbitrary1 ((,) a) Source # 

Methods

liftArbitrary :: Gen a -> Gen (a, a) Source #

liftShrink :: (a -> [a]) -> (a, a) -> [(a, a)] Source #

(Ord k, Arbitrary k) => Arbitrary1 (Map k) Source # 

Methods

liftArbitrary :: Gen a -> Gen (Map k a) Source #

liftShrink :: (a -> [a]) -> Map k a -> [Map k a] Source #

Arbitrary a => Arbitrary1 (Const * a) Source # 

Methods

liftArbitrary :: Gen a -> Gen (Const * a a) Source #

liftShrink :: (a -> [a]) -> Const * a a -> [Const * a a] Source #

Arbitrary a => Arbitrary1 (Constant * a) Source # 

Methods

liftArbitrary :: Gen a -> Gen (Constant * a a) Source #

liftShrink :: (a -> [a]) -> Constant * a a -> [Constant * a a] Source #

CoArbitrary a => Arbitrary1 ((->) LiftedRep LiftedRep a) Source # 

Methods

liftArbitrary :: Gen a -> Gen ((LiftedRep -> LiftedRep) a a) Source #

liftShrink :: (a -> [a]) -> (LiftedRep -> LiftedRep) a a -> [(LiftedRep -> LiftedRep) a a] Source #

(Arbitrary1 f, Arbitrary1 g) => Arbitrary1 (Product * f g) Source # 

Methods

liftArbitrary :: Gen a -> Gen (Product * f g a) Source #

liftShrink :: (a -> [a]) -> Product * f g a -> [Product * f g a] Source #

(Arbitrary1 f, Arbitrary1 g) => Arbitrary1 (Compose * * f g) Source # 

Methods

liftArbitrary :: Gen a -> Gen (Compose * * f g a) Source #

liftShrink :: (a -> [a]) -> Compose * * f g a -> [Compose * * f g a] Source #

shrink1 :: (Arbitrary1 f, Arbitrary a) => f a -> [f a] Source #

class Arbitrary2 f where Source #

Lifting of the Arbitrary class to binary type constructors.

Minimal complete definition

liftArbitrary2

Methods

liftArbitrary2 :: Gen a -> Gen b -> Gen (f a b) Source #

liftShrink2 :: (a -> [a]) -> (b -> [b]) -> f a b -> [f a b] Source #

Instances

Arbitrary2 Either Source # 

Methods

liftArbitrary2 :: Gen a -> Gen b -> Gen (Either a b) Source #

liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Either a b -> [Either a b] Source #

Arbitrary2 (,) Source # 

Methods

liftArbitrary2 :: Gen a -> Gen b -> Gen (a, b) Source #

liftShrink2 :: (a -> [a]) -> (b -> [b]) -> (a, b) -> [(a, b)] Source #

Arbitrary2 (Const *) Source # 

Methods

liftArbitrary2 :: Gen a -> Gen b -> Gen (Const * a b) Source #

liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Const * a b -> [Const * a b] Source #

Arbitrary2 (Constant *) Source # 

Methods

liftArbitrary2 :: Gen a -> Gen b -> Gen (Constant * a b) Source #

liftShrink2 :: (a -> [a]) -> (b -> [b]) -> Constant * a b -> [Constant * a b] Source #

shrink2 :: (Arbitrary2 f, Arbitrary a, Arbitrary b) => f a b -> [f a b] Source #

Helper functions for implementing arbitrary

applyArbitrary2 :: (Arbitrary a, Arbitrary b) => (a -> b -> r) -> Gen r Source #

Apply a binary function to random arguments.

applyArbitrary3 :: (Arbitrary a, Arbitrary b, Arbitrary c) => (a -> b -> c -> r) -> Gen r Source #

Apply a ternary function to random arguments.

applyArbitrary4 :: (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => (a -> b -> c -> d -> r) -> Gen r Source #

Apply a function of arity 4 to random arguments.

arbitrarySizedIntegral :: Integral a => Gen a Source #

Generates an integral number. The number can be positive or negative and its maximum absolute value depends on the size parameter.

arbitrarySizedNatural :: Integral a => Gen a Source #

Generates a natural number. The number's maximum value depends on the size parameter.

arbitraryBoundedIntegral :: (Bounded a, Integral a) => Gen a Source #

Generates an integral number. The number is chosen uniformly from the entire range of the type. You may want to use arbitrarySizedBoundedIntegral instead.

arbitrarySizedBoundedIntegral :: (Bounded a, Integral a) => Gen a Source #

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.

arbitrarySizedFractional :: Fractional a => Gen a Source #

Generates a fractional number. The number can be positive or negative and its maximum absolute value depends on the size parameter.

arbitraryBoundedRandom :: (Bounded a, Random a) => Gen a Source #

Generates an element of a bounded type. The element is chosen from the entire range of the type.

arbitraryBoundedEnum :: (Bounded a, Enum a) => Gen a Source #

Generates an element of a bounded enumeration.

Generators for various kinds of character

arbitraryUnicodeChar :: Gen Char Source #

Generates any Unicode character (but not a surrogate)

arbitraryASCIIChar :: Gen Char Source #

Generates a random ASCII character (0-127).

arbitraryPrintableChar :: Gen Char Source #

Generates a printable Unicode character.

Helper functions for implementing shrink

genericShrink :: (Generic a, RecursivelyShrink (Rep a), GSubterms (Rep a) a) => a -> [a] Source #

Shrink a term to any of its immediate subterms, and also recursively shrink all subterms.

subterms :: (Generic a, GSubterms (Rep a) a) => a -> [a] Source #

All immediate subterms of a term.

recursivelyShrink :: (Generic a, RecursivelyShrink (Rep a)) => a -> [a] Source #

Recursively shrink all immediate subterms.

genericCoarbitrary :: (Generic a, GCoArbitrary (Rep a)) => a -> Gen b -> Gen b Source #

Generic CoArbitrary implementation.

shrinkNothing :: a -> [a] Source #

Returns no shrinking alternatives.

shrinkList :: (a -> [a]) -> [a] -> [[a]] Source #

Shrink a list of values given a shrinking function for individual values.

shrinkMap :: Arbitrary a => (a -> b) -> (b -> a) -> b -> [b] Source #

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

shrinkMapBy :: (a -> b) -> (b -> a) -> (a -> [a]) -> b -> [b] Source #

Non-overloaded version of shrinkMap.

shrinkIntegral :: Integral a => a -> [a] Source #

Shrink an integral number.

shrinkRealFrac :: RealFrac a => a -> [a] Source #

Shrink a fraction.

Helper functions for implementing coarbitrary

coarbitraryIntegral :: Integral a => a -> Gen b -> Gen b Source #

A coarbitrary implementation for integral numbers.

coarbitraryReal :: Real a => a -> Gen b -> Gen b Source #

A coarbitrary implementation for real numbers.

coarbitraryShow :: Show a => a -> Gen b -> Gen b Source #

coarbitrary helper for lazy people :-).

coarbitraryEnum :: Enum a => a -> Gen b -> Gen b Source #

A coarbitrary implementation for enums.

(><) :: (Gen a -> Gen a) -> (Gen a -> Gen a) -> Gen a -> Gen a Source #

Deprecated: Use ordinary function composition instead

Combine two generator perturbing functions, for example the results of calls to variant or coarbitrary.

Generators which use arbitrary

vector :: Arbitrary a => Int -> Gen [a] Source #

Generates a list of a given length.

orderedList :: (Ord a, Arbitrary a) => Gen [a] Source #

Generates an ordered list.

infiniteList :: Arbitrary a => Gen [a] Source #

Generates an infinite list.