Safe Haskell | None |
---|---|
Language | Haskell2010 |
GenValidity
exists to make tests involving Validity
types easier and speed
up the generation of data for them.
Let's use the example from Data.Validity
again: A datatype that represents
primes.
To implement tests for this datatype, we would have to be able to generate
both primes and non-primes. We could do this with
(Prime $ arbitrary)
but this is tedious and inefficient.suchThat
isValid
The GenValid
type class allows you to specify how to (efficiently)
generate valid data of the given type to allow for easier and quicker testing.
Just instantiating GenUnchecked
already gives you access to a default instance
of GenValid
and GenInvalid
but writing custom implementations of these functions
may speed up the generation of data.
For example, to generate primes, we don't have to consider even numbers other than 2. A more efficient implementation could then look as follows:
instance GenUnchecked Prime where genUnchecked = Prime <$> arbitrary
instance GenValid Prime where genValid = Prime <$> (oneof [ pure 2 , ((\y -> 2 * abs y + 1) <$> arbitrary) `suchThat` isPrime) ])
Typical examples of tests involving validity could look as follows:
it "succeeds when given valid input" $ do forAllValid $ \input -> myFunction input `shouldSatisfy` isRight
it "produces valid output when it succeeds" $ do forAllUnchecked $ \input -> case myFunction input of Nothing -> return () -- Can happen Just output -> output `shouldSatisfy` isValid
- module Data.Validity
- class GenUnchecked a where
- class (Validity a, GenUnchecked a) => GenValid a where
- class (Validity a, GenUnchecked a) => GenInvalid a where
- shrinkT2 :: (a -> [a]) -> (a, a) -> [(a, a)]
- shrinkT3 :: (a -> [a]) -> (a, a, a) -> [(a, a, a)]
- upTo :: Int -> Gen Int
- genSplit :: Int -> Gen (Int, Int)
- genSplit3 :: Int -> Gen (Int, Int, Int)
- genSplit4 :: Int -> Gen (Int, Int, Int, Int)
- genSplit5 :: Int -> Gen (Int, Int, Int, Int, Int)
- arbPartition :: Int -> Gen [Int]
- genListOf :: Gen a -> Gen [a]
- class GGenUnchecked f where
- gShrinkUnchecked :: (Generic a, GUncheckedRecursivelyShrink (Rep a), GUncheckedSubterms (Rep a) a) => a -> [a]
- uncheckedRecursivelyShrink :: (Generic a, GUncheckedRecursivelyShrink (Rep a)) => a -> [a]
- class GUncheckedRecursivelyShrink f where
- uncheckedSubterms :: (Generic a, GUncheckedSubterms (Rep a) a) => a -> [a]
- class GUncheckedSubterms f a where
- class GUncheckedSubtermsIncl f a where
Documentation
module Data.Validity
class GenUnchecked a where Source #
A class of types for which truly arbitrary values can be generated.
Automatic instances with Generic
An instance of this class can be made automatically if the type in question
has a Generic
instance. This instance will try to use genUnchecked
to
generate all structural sub-parts of the value that is being generated.
Example:
{-# LANGUAGE DeriveGeneric #-} data MyType = MyType Double String deriving (Show, Eq, Generic) instance GenUnchecked MyType
generates something like:
instance GenUnchecked MyType where genUnchecked = MyType <$> genUnchecked <*> genUnchecked
genUnchecked :: Gen a Source #
genUnchecked :: (Generic a, GGenUnchecked (Rep a)) => Gen a Source #
shrinkUnchecked :: a -> [a] Source #
shrinkUnchecked :: (Generic a, GUncheckedRecursivelyShrink (Rep a), GUncheckedSubterms (Rep a) a) => a -> [a] Source #
class (Validity a, GenUnchecked a) => GenValid a where Source #
A class of types for which valid values can be generated.
If you also write Arbitrary
instances for GenValid
types, it may be
best to simply write arbitrary = genValid
.
class (Validity a, GenUnchecked a) => GenInvalid a where Source #
A class of types for which invalid values can be generated.
genInvalid :: Gen a Source #
shrinkInvalid :: a -> [a] Source #
GenInvalid Double Source # | Either |
GenInvalid Float Source # | Either |
GenInvalid a => GenInvalid [a] Source # | This instance ensures that the generated list contains at least one element
that satisfies |
GenInvalid a => GenInvalid (Maybe a) Source # | |
(Integral a, Num a, Ord a, GenValid a) => GenInvalid (Ratio a) Source # | |
GenInvalid a => GenInvalid (NonEmpty a) Source # | |
(GenInvalid a, GenInvalid b) => GenInvalid (Either a b) Source # | This instance ensures that the generated tupse contains at least one invalid element. The other element is unchecked. |
(GenInvalid a, GenInvalid b) => GenInvalid (a, b) Source # | |
(GenInvalid a, GenInvalid b, GenInvalid c) => GenInvalid (a, b, c) Source # | This instance ensures that the generated triple contains at least one invalid element. The other two are unchecked. |
(GenInvalid a, GenInvalid b, GenInvalid c, GenInvalid d) => GenInvalid (a, b, c, d) Source # | This instance ensures that the generated triple contains at least one invalid element. The other two are unchecked. |
(GenInvalid a, GenInvalid b, GenInvalid c, GenInvalid d, GenInvalid e) => GenInvalid (a, b, c, d, e) Source # | This instance ensures that the generated triple contains at least one invalid element. The other two are unchecked. |
genSplit :: Int -> Gen (Int, Int) Source #
'genSplit a' generates a tuple '(b, c)' such that 'b + c' equals a
.
genSplit3 :: Int -> Gen (Int, Int, Int) Source #
'genSplit3 a' generates a triple '(b, c, d)' such that 'b + c + d' equals a
.
genSplit4 :: Int -> Gen (Int, Int, Int, Int) Source #
'genSplit4 a' generates a quadruple '(b, c, d, e)' such that 'b + c + d + e' equals a
.
genSplit5 :: Int -> Gen (Int, Int, Int, Int, Int) Source #
'genSplit5 a' generates a quadruple '(b, c, d, e, f)' such that 'b + c + d + e + f' equals a
.
arbPartition :: Int -> Gen [Int] Source #
'arbPartition n' generates a list ls
such that 'sum ls' equals n
.
genListOf :: Gen a -> Gen [a] Source #
A version of listOf
that takes size into account more accurately.
class GGenUnchecked f where Source #
gGenUnchecked :: Gen (f a) Source #
GGenUnchecked (U1 *) Source # | |
GenUnchecked a => GGenUnchecked (K1 * i a) Source # | |
(GGenUnchecked a, GGenUnchecked b) => GGenUnchecked ((:+:) * a b) Source # | |
(GGenUnchecked a, GGenUnchecked b) => GGenUnchecked ((:*:) * a b) Source # | |
GGenUnchecked a => GGenUnchecked (M1 * i c a) Source # | |
gShrinkUnchecked :: (Generic a, GUncheckedRecursivelyShrink (Rep a), GUncheckedSubterms (Rep a) a) => a -> [a] Source #
Shrink a term to any of its immediate subterms, and also recursively shrink all subterms.
uncheckedRecursivelyShrink :: (Generic a, GUncheckedRecursivelyShrink (Rep a)) => a -> [a] Source #
Recursively shrink all immediate uncheckedSubterms.
class GUncheckedRecursivelyShrink f where Source #
gUncheckedRecursivelyShrink :: f a -> [f a] Source #
GUncheckedRecursivelyShrink (V1 *) Source # | |
GUncheckedRecursivelyShrink (U1 *) Source # | |
GenUnchecked a => GUncheckedRecursivelyShrink (K1 * i a) Source # | |
(GUncheckedRecursivelyShrink f, GUncheckedRecursivelyShrink g) => GUncheckedRecursivelyShrink ((:+:) * f g) Source # | |
(GUncheckedRecursivelyShrink f, GUncheckedRecursivelyShrink g) => GUncheckedRecursivelyShrink ((:*:) * f g) Source # | |
GUncheckedRecursivelyShrink f => GUncheckedRecursivelyShrink (M1 * i c f) Source # | |
uncheckedSubterms :: (Generic a, GUncheckedSubterms (Rep a) a) => a -> [a] Source #
All immediate uncheckedSubterms of a term.
class GUncheckedSubterms f a where Source #
gUncheckedSubterms :: f a -> [a] Source #
GUncheckedSubterms (V1 *) a Source # | |
GUncheckedSubterms (U1 *) a Source # | |
GUncheckedSubterms (K1 * i a) b Source # | |
(GUncheckedSubtermsIncl f a, GUncheckedSubtermsIncl g a) => GUncheckedSubterms ((:+:) * f g) a Source # | |
(GUncheckedSubtermsIncl f a, GUncheckedSubtermsIncl g a) => GUncheckedSubterms ((:*:) * f g) a Source # | |
GUncheckedSubterms f a => GUncheckedSubterms (M1 * i c f) a Source # | |
class GUncheckedSubtermsIncl f a where Source #
gUncheckedSubtermsIncl :: f a -> [a] Source #
GUncheckedSubtermsIncl (V1 *) a Source # | |
GUncheckedSubtermsIncl (U1 *) a Source # | |
GUncheckedSubtermsIncl (K1 * i a) b Source # | |
GUncheckedSubtermsIncl (K1 * i a) a Source # | |
(GUncheckedSubtermsIncl f a, GUncheckedSubtermsIncl g a) => GUncheckedSubtermsIncl ((:+:) * f g) a Source # | |
(GUncheckedSubtermsIncl f a, GUncheckedSubtermsIncl g a) => GUncheckedSubtermsIncl ((:*:) * f g) a Source # | |
GUncheckedSubtermsIncl f a => GUncheckedSubtermsIncl (M1 * i c f) a Source # | |