Package net.jqwik.api

Class Arbitraries

java.lang.Object

net.jqwik.api.Arbitraries

@API(status=STABLE,
     since="1.0")
public class Arbitraries
extends java.lang.Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Arbitraries.ArbitrariesFacade

Method Summary

Modifier and Type	Method	Description
static BigDecimalArbitrary	bigDecimals()	Create an arbitrary that generates values of type BigDecimal.
static BigIntegerArbitrary	bigIntegers()	Create an arbitrary that generates values of type BigInteger.
static ByteArbitrary	bytes()	Create an arbitrary that generates values of type Byte.
static CharacterArbitrary	chars()	Create an arbitrary that generates values of type Character.
static <T> Arbitrary<T>	create(java.util.function.Supplier<T> supplier)	Create an arbitrary that will use a supplier to generate a value.
static <T> Arbitrary<T>	defaultFor(java.lang.Class<T> type, java.lang.Class<?>... typeParameters)	Find a registered arbitrary that will be used to generate values of type T.
static <T> Arbitrary<T>	defaultFor(TypeUsage typeUsage)	Find a registered arbitrary that will be used to generate values of type T.
static <T> Arbitrary<T>	defaultFor(TypeUsage typeUsage, java.util.function.Function<TypeUsage,Arbitrary<java.lang.Object>> noDefaultResolver)	Find a registered arbitrary that will be used to generate values of type T.
static DoubleArbitrary	doubles()	Create an arbitrary that generates values of type Double.
static <K,V> Arbitrary<java.util.Map.Entry<K,V>>	entries(Arbitrary<K> keysArbitrary, Arbitrary<V> valuesArbitrary)	Create an arbitrary to create instances of Map.Entry.
static FloatArbitrary	floats()	Create an arbitrary that generates values of type Float.
static <T> TypeArbitrary<T>	forType(java.lang.Class<T> targetType)	Create an arbitrary for type T that will by default use the type's public constructors and public factory methods.
static <T> Arbitrary<T>	frequency(java.util.List<Tuple.Tuple2<java.lang.Integer,T>> frequencies)	Create an arbitrary that will randomly choose between all given values of the same type T.
static <T> Arbitrary<T>	frequency(Tuple.Tuple2<java.lang.Integer,T>... frequencies)	Create an arbitrary that will randomly choose between all given values of the same type T.
static <T> Arbitrary<T>	frequencyOf(java.util.List<Tuple.Tuple2<java.lang.Integer,Arbitrary<T>>> frequencies)	Create an arbitrary that will randomly choose between all given arbitraries of the same type T.
static <T> Arbitrary<T>	frequencyOf(Tuple.Tuple2<java.lang.Integer,Arbitrary<? extends T>>... frequencies)	Create an arbitrary that will randomly choose between all given arbitraries of the same type T.
static <T> Arbitrary<T>	fromGenerator(RandomGenerator<T> generator)	Create an arbitrary of type T from a corresponding generator of type T.
static IntegerArbitrary	integers()	Create an arbitrary that generates values of type Integer.
static <T> Arbitrary<T>	just(T value)	Create an arbitrary that will always generate the same value.
static <T> Arbitrary<T>	lazy(java.util.function.Supplier<Arbitrary<T>> arbitrarySupplier)	Create an arbitrary that will evaluate arbitrarySupplier as soon as it is used for generating values.
static <T> Arbitrary<T>	lazyOf(java.util.function.Supplier<Arbitrary<? extends T>> first, java.util.function.Supplier<Arbitrary<? extends T>>... rest)	Create an arbitrary by lazy supplying one of several arbitraries.
static LongArbitrary	longs()	Create an arbitrary that generates values of type Long.
static <K,V> MapArbitrary<K,V>	maps(Arbitrary<K> keysArbitrary, Arbitrary<V> valuesArbitrary)	Create an arbitrary to create instances of Map.
static Arbitrary<java.lang.Void>	nothing()	Create an arbitrary that never creates anything.
static Arbitrary<java.lang.Character>	of(char[] values)	Create an arbitrary of character values.
static <T extends java.lang.Enum<T>> Arbitrary<T>	of(java.lang.Class<T> enumClass)	Create an arbitrary for enum values of type T.
static <T> Arbitrary<T>	of(java.util.Collection<T> values)	Create an arbitrary that will randomly choose from a given collection of values.
static <T> Arbitrary<T>	of(T... values)	Create an arbitrary that will randomly choose from a given array of values.
static <T> Arbitrary<T>	ofSuppliers(java.util.Collection<java.util.function.Supplier<T>> valueSuppliers)	Create an arbitrary that will randomly choose from a given collection of value suppliers and then get the value from the supplier.
static <T> Arbitrary<T>	ofSuppliers(java.util.function.Supplier<T>... valueSuppliers)	Create an arbitrary that will randomly choose from a given array of value suppliers and then get the value from the supplier.
static <T> Arbitrary<T>	oneOf(java.util.Collection<Arbitrary<? extends T>> choices)	Create an arbitrary that will randomly choose between all given arbitraries of the same type T.
static <T> Arbitrary<T>	oneOf(Arbitrary<? extends T> first, Arbitrary<? extends T>... rest)	Create an arbitrary that will randomly choose between all given arbitraries of the same type T.
static Arbitrary<java.util.Random>	randoms()	Create an arbitrary for Random objects.
static <T> Arbitrary<T>	randomValue(java.util.function.Function<java.util.Random,T> generator)	Create an arbitrary that will generate values of type T using a generator function.
static <T> Arbitrary<T>	recursive(java.util.function.Supplier<Arbitrary<T>> base, java.util.function.Function<Arbitrary<T>,Arbitrary<T>> recur, int depth)	Create an arbitrary by deterministic recursion.
static <T> Arbitrary<T>	recursive(java.util.function.Supplier<Arbitrary<T>> base, java.util.function.Function<Arbitrary<T>,Arbitrary<T>> recur, int minDepth, int maxDepth)	Create an arbitrary by deterministic recursion.
static <M> ActionSequenceArbitrary<M>	sequences(Arbitrary<? extends Action<M>> actionArbitrary)	Create an arbitrary to create a sequence of actions.
static ShortArbitrary	shorts()	Create an arbitrary that generates values of type Short.
static <T> Arbitrary<java.util.List<T>>	shuffle(java.util.List<T> values)	Create an arbitrary that will always generate a list which is a permutation of the values handed to it.
static <T> Arbitrary<java.util.List<T>>	shuffle(T... values)	Create an arbitrary that will always generate a list which is a permutation of the values handed to it.
static StringArbitrary	strings()	Create an arbitrary that generates values of type String.
static <T> SetArbitrary<T>	subsetOf(java.util.Collection<T> values)	Create a new arbitrary of element type Set<T> using the handed in values as elements of the set.
static <T> SetArbitrary<T>	subsetOf(T... values)	Create a new arbitrary of element type Set<T> using the handed in values as elements of the set.
static <T> TraverseArbitrary<T>	traverse(java.lang.Class<T> targetType, TraverseArbitrary.Traverser traverser)	Create an arbitrary for type T that will try to traverse a type - and all types it is based on - given a TraverseArbitrary.Traverser strategy.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

fromGenerator

public static <T> Arbitrary<T> fromGenerator(RandomGenerator<T> generator)

Create an arbitrary of type T from a corresponding generator of type T.

Type Parameters:

T - The type of values to generate

Parameters:

generator - The generator to be used for generating the values

Returns:

a new arbitrary instance

randomValue

public static <T> Arbitrary<T> randomValue(java.util.function.Function<java.util.Random,T> generator)

Create an arbitrary that will generate values of type T using a generator function. The generated values are unshrinkable.

Type Parameters:

T - The type of values to generate

Parameters:

generator - The generator function to be used for generating the values

Returns:

a new arbitrary instance

randoms

public static Arbitrary<java.util.Random> randoms()

Create an arbitrary for Random objects.

Returns:

a new arbitrary instance

of

@SafeVarargs
public static <T> Arbitrary<T> of(T... values)

Create an arbitrary that will randomly choose from a given array of values. A generated value will be shrunk towards the start of the array.

Use this method only for immutable values, because changing the value will change subsequent generated values as well. For mutable values use ofSuppliers(Supplier[]) instead.

Type Parameters:

T - The type of values to generate

Parameters:

values - The array of values to choose from

Returns:

a new arbitrary instance

of

@API(status=MAINTAINED,
     since="1.3.1")
public static <T> Arbitrary<T> of(java.util.Collection<T> values)

Create an arbitrary that will randomly choose from a given collection of values. A generated value will be shrunk towards the start of the collection.

Use this method only for immutable values, because changing the value will change subsequent generated values as well. For mutable values use ofSuppliers(Collection) instead.

Type Parameters:

T - The type of values to generate

Parameters:

values - The collection of values to choose from

Returns:

a new arbitrary instance

ofSuppliers

@API(status=MAINTAINED,
     since="1.3.0")
@SafeVarargs
public static <T> Arbitrary<T> ofSuppliers(java.util.function.Supplier<T>... valueSuppliers)

Create an arbitrary that will randomly choose from a given array of value suppliers and then get the value from the supplier. A generated value will be shrunk towards the start of the array.

Use this method instead of of(Object[]) for mutable objects to make sure that changing a generated object will not influence other generated objects.

Type Parameters:

T - The type of values to generate

Parameters:

valueSuppliers - The array of values to choose from

Returns:

a new arbitrary instance

ofSuppliers

@API(status=MAINTAINED,
     since="1.3.1")
public static <T> Arbitrary<T> ofSuppliers(java.util.Collection<java.util.function.Supplier<T>> valueSuppliers)

Create an arbitrary that will randomly choose from a given collection of value suppliers and then get the value from the supplier. A generated value will be shrunk towards the start of the collection.

Use this method instead of of(Collection) for mutable objects to make sure that changing a generated object will not influence other generated objects.

Type Parameters:

T - The type of values to generate

Parameters:

valueSuppliers - The collection of values to choose from

Returns:

a new arbitrary instance

of

public static Arbitrary<java.lang.Character> of(char[] values)

Create an arbitrary of character values.

Parameters:

values - The array of characters to choose from.

Returns:

a new arbitrary instance

of

public static <T extends java.lang.Enum<T>> Arbitrary<T> of(java.lang.Class<T> enumClass)

Create an arbitrary for enum values of type T.

Type Parameters:

T - The type of values to generate

Parameters:

enumClass - The enum class.

Returns:

a new arbitrary instance

oneOf

public static <T> Arbitrary<T> oneOf(Arbitrary<? extends T> first,
                                     Arbitrary<? extends T>... rest)

Create an arbitrary that will randomly choose between all given arbitraries of the same type T.

Type Parameters:

T - The type of values to generate

Parameters:

first - The first arbitrary to choose form

rest - An array of arbitraries to choose from

Returns:

a new arbitrary instance

oneOf

public static <T> Arbitrary<T> oneOf(java.util.Collection<Arbitrary<? extends T>> choices)

Create an arbitrary that will randomly choose between all given arbitraries of the same type T.

Type Parameters:

T - The type of values to generate

Parameters:

choices - A collection of arbitraries to choose from

Returns:

a new arbitrary instance

frequency

@SafeVarargs
public static <T> Arbitrary<T> frequency(Tuple.Tuple2<java.lang.Integer,T>... frequencies)

Create an arbitrary that will randomly choose between all given values of the same type T. The probability distribution is weighted with the first parameter of the tuple.

Type Parameters:

T - The type of values to generate

Parameters:

frequencies - An array of tuples of which the first parameter gives the weight and the second the value.

Returns:

a new arbitrary instance

frequency

public static <T> Arbitrary<T> frequency(java.util.List<Tuple.Tuple2<java.lang.Integer,T>> frequencies)

Create an arbitrary that will randomly choose between all given values of the same type T. The probability distribution is weighted with the first parameter of the tuple.

Type Parameters:

T - The type of values to generate

Parameters:

frequencies - A list of tuples of which the first parameter gives the weight and the second the value.

Returns:

a new arbitrary instance

frequencyOf

@SafeVarargs
public static <T> Arbitrary<T> frequencyOf(Tuple.Tuple2<java.lang.Integer,Arbitrary<? extends T>>... frequencies)

Create an arbitrary that will randomly choose between all given arbitraries of the same type T. The probability distribution is weighted with the first parameter of the tuple.

Type Parameters:

T - The type of values to generate

Parameters:

frequencies - An array of tuples of which the first parameter gives the weight and the second the arbitrary.

Returns:

a new arbitrary instance

frequencyOf

public static <T> Arbitrary<T> frequencyOf(java.util.List<Tuple.Tuple2<java.lang.Integer,Arbitrary<T>>> frequencies)

Create an arbitrary that will randomly choose between all given arbitraries of the same type T. The probability distribution is weighted with the first parameter of the tuple.

Type Parameters:

T - The type of values to generate

Parameters:

frequencies - A list of tuples of which the first parameter gives the weight and the second the arbitrary.

Returns:

a new arbitrary instance

integers

public static IntegerArbitrary integers()

Create an arbitrary that generates values of type Integer.

Returns:

a new arbitrary instance

longs

public static LongArbitrary longs()

Create an arbitrary that generates values of type Long.

Returns:

a new arbitrary instance

bigIntegers

public static BigIntegerArbitrary bigIntegers()

Create an arbitrary that generates values of type BigInteger.

Returns:

a new arbitrary instance

floats

public static FloatArbitrary floats()

Create an arbitrary that generates values of type Float.

Returns:

a new arbitrary instance

bigDecimals

public static BigDecimalArbitrary bigDecimals()

Create an arbitrary that generates values of type BigDecimal.

Returns:

a new arbitrary instance

doubles

public static DoubleArbitrary doubles()

Create an arbitrary that generates values of type Double.

Returns:

a new arbitrary instance

bytes

public static ByteArbitrary bytes()

Create an arbitrary that generates values of type Byte.

Returns:

a new arbitrary instance

shorts

public static ShortArbitrary shorts()

Create an arbitrary that generates values of type Short.

Returns:

a new arbitrary instance

strings

public static StringArbitrary strings()

Create an arbitrary that generates values of type String.

Returns:

a new arbitrary instance

chars

public static CharacterArbitrary chars()

Create an arbitrary that generates values of type Character.

Returns:

a new arbitrary instance

just

@API(status=MAINTAINED,
     since="1.3.2")
public static <T> Arbitrary<T> just(@Nullable
                                    T value)

Create an arbitrary that will always generate the same value.

Type Parameters:

T - The type of the value

Parameters:

value - The value to "generate".

Returns:

a new arbitrary instance

create

@API(status=MAINTAINED,
     since="1.1.1")
public static <T> Arbitrary<T> create(java.util.function.Supplier<T> supplier)

Create an arbitrary that will use a supplier to generate a value. The difference to just(Object) is that the value is freshly generated for each try of a property.

For exhaustive shrinking all generated values are supposed to have identical behaviour, i.e. that means that only one value is generated per combination.

Type Parameters:

T - The type of values to generate

Parameters:

supplier - The supplier use to generate a value

Returns:

a new arbitrary instance

shuffle

@SafeVarargs
public static <T> Arbitrary<java.util.List<T>> shuffle(T... values)

Create an arbitrary that will always generate a list which is a permutation of the values handed to it. Permutations will not be shrunk.

Type Parameters:

T - The type of values to generate

Parameters:

values - The values to permute

Returns:

a new arbitrary instance

shuffle

public static <T> Arbitrary<java.util.List<T>> shuffle(java.util.List<T> values)

Create an arbitrary that will always generate a list which is a permutation of the values handed to it. Permutations will not be shrunk.

Type Parameters:

T - The type of values to generate

Parameters:

values - The values to permute

Returns:

a new arbitrary instance

defaultFor

public static <T> Arbitrary<T> defaultFor(java.lang.Class<T> type,
                                          java.lang.Class<?>... typeParameters)

Find a registered arbitrary that will be used to generate values of type T. All default arbitrary providers and all registered arbitrary providers are considered. This is more or less the same mechanism that jqwik uses to find arbitraries for property method parameters.

Type Parameters:

T - The type of values to generate

Parameters:

type - The type of the value to find an arbitrary for

typeParameters - The type parameters if type is a generic type

Returns:

a new arbitrary instance

Throws:

CannotFindArbitraryException - if there is no registered arbitrary provider to serve this type

defaultFor

@API(status=MAINTAINED,
     since="1.1")
public static <T> Arbitrary<T> defaultFor(TypeUsage typeUsage)

Find a registered arbitrary that will be used to generate values of type T. All default arbitrary providers and all registered arbitrary providers are considered. This is more or less the same mechanism that jqwik uses to find arbitraries for property method parameters.

The returned arbitrary is lazy, i.e. it be evaluated at generation time to allow domain contexts to be used.

Type Parameters:

T - The type of values to generate

Parameters:

typeUsage - The type of the value to find an arbitrary for

Returns:

a new arbitrary instance

defaultFor

@API(status=EXPERIMENTAL,
     since="1.6.1")
public static <T> Arbitrary<T> defaultFor(TypeUsage typeUsage,
                                          java.util.function.Function<TypeUsage,Arbitrary<java.lang.Object>> noDefaultResolver)

Find a registered arbitrary that will be used to generate values of type T. All default arbitrary providers and all registered arbitrary providers are considered. This is more or less the same mechanism that jqwik uses to find arbitraries for property method parameters.

The returned arbitrary is lazy, i.e. it be evaluated at generation time to allow domain contexts to be used. Those

Type Parameters:

T - The type of values to generate

Parameters:

typeUsage - The type of the value to find an arbitrary for

noDefaultResolver - Alternative resolution when no default arbitrary can be found at generation time

Returns:

a new arbitrary instance

forType

@API(status=MAINTAINED,
     since="1.2.0")
public static <T> TypeArbitrary<T> forType(java.lang.Class<T> targetType)

Create an arbitrary for type T that will by default use the type's public constructors and public factory methods.

Type Parameters:

T - The type of values to generate

Parameters:

targetType - The class of the type to create an arbitrary for

Returns:

a new arbitrary instance

See Also:

TypeArbitrary

traverse

@API(status=EXPERIMENTAL,
     since="1.6.1")
public static <T> TraverseArbitrary<T> traverse(java.lang.Class<T> targetType,
                                                TraverseArbitrary.Traverser traverser)

Create an arbitrary for type T that will try to traverse a type - and all types it is based on - given a TraverseArbitrary.Traverser strategy.

By default recursion is disable, i.e. that parameters of creator functions can be resolved by the traverser, have a default arbitrary or generation fails at runtime. Use TraverseArbitrary.enableRecursion() to switch on recursive traversal.

One usage of this traversing mechanism is forType(Class) which uses traverse(Class, Traverser) under the hood.

Type Parameters:

T - The type of values to generate

Parameters:

targetType - The class of the type to create an arbitrary for

traverser - The traversing strategy specification

Returns:

a new arbitrary instance

See Also:

TraverseArbitrary

lazy

public static <T> Arbitrary<T> lazy(java.util.function.Supplier<Arbitrary<T>> arbitrarySupplier)

Create an arbitrary that will evaluate arbitrarySupplier as soon as it is used for generating values.

This is useful (and necessary) when arbitrary providing functions use other arbitrary providing functions in a recursive way. Without the use of lazy() this would result in a stack overflow. Most of the time, however, using lazyOf(Supplier, Supplier[]) is the better choice because it has significantly better shrinking behaviour.

Type Parameters:

T - The type of values to generate

Parameters:

arbitrarySupplier - The supplier function being used to generate an arbitrary

Returns:

a new arbitrary instance

See Also:

recursive(Supplier, Function, int), lazyOf(Supplier, Supplier[])

recursive

public static <T> Arbitrary<T> recursive(java.util.function.Supplier<Arbitrary<T>> base,
                                         java.util.function.Function<Arbitrary<T>,Arbitrary<T>> recur,
                                         int depth)

Create an arbitrary by deterministic recursion.

Mind that the arbitrary will be created by invoking recursion at arbitrary creation time. Using lazyOf(Supplier, Supplier[]) or lazy(Supplier) instead will recur at value generation time.

Type Parameters:

T - The type of values to generate

Parameters:

base - The supplier returning the recursion's base case

recur - The function to extend the base case

depth - The number of times to invoke recursion

Returns:

a new arbitrary instance

See Also:

lazy(Supplier)

recursive

@API(status=MAINTAINED,
     since="1.6.4")
public static <T> Arbitrary<T> recursive(java.util.function.Supplier<Arbitrary<T>> base,
                                         java.util.function.Function<Arbitrary<T>,Arbitrary<T>> recur,
                                         int minDepth,
                                         int maxDepth)

Create an arbitrary by deterministic recursion.

Mind that the arbitrary will be created by invoking recursion at arbitrary creation time. Using lazyOf(Supplier, Supplier[]) or lazy(Supplier) instead will recur at value generation time.

Type Parameters:

T - The type of values to generate

Parameters:

base - The supplier returning the recursion's base case

recur - The function to extend the base case

minDepth - The minimum number of times to invoke recursion

maxDepth - The maximum number of times to invoke recursion

Returns:

a new arbitrary instance

See Also:

lazy(Supplier)

lazyOf

@SafeVarargs
@API(status=MAINTAINED,
     since="1.3.4")
public static <T> Arbitrary<T> lazyOf(java.util.function.Supplier<Arbitrary<? extends T>> first,
                                      java.util.function.Supplier<Arbitrary<? extends T>>... rest)

Create an arbitrary by lazy supplying one of several arbitraries. The main use of this function is to allow recursive generation of structured values without overflowing the stack.

One alternative is to use lazy(Supplier) combined with oneOf(Arbitrary, Arbitrary[]) or frequencyOf(Tuple.Tuple2[]). But lazyOf() has considerably better shrinking behaviour with recursion.

Caveat: Never use this construct if suppliers make use of variable state like method parameters or changing instance members. In those cases use lazy(Supplier) instead.

Type Parameters:

T - The type of values to generate

Parameters:

first - The first supplier to choose from

rest - The rest of suppliers to choose from

Returns:

a (potentially cached) arbitrary instance

See Also:

lazy(Supplier), recursive(Supplier, Function, int)

sequences

@API(status=MAINTAINED,
     since="1.0")
public static <M> ActionSequenceArbitrary<M> sequences(Arbitrary<? extends Action<M>> actionArbitrary)

Create an arbitrary to create a sequence of actions. Useful for stateful testing.

Type Parameters:

M - The type of actions to generate

Parameters:

actionArbitrary - The arbitrary to generate individual actions.

Returns:

a new arbitrary instance

maps

@API(status=MAINTAINED,
     since="1.1.6")
public static <K,V> MapArbitrary<K,V> maps(Arbitrary<K> keysArbitrary,
                                                       Arbitrary<V> valuesArbitrary)

Create an arbitrary to create instances of Map. The generated maps are mutable.

Type Parameters:

K - type of keys

V - type of values

Parameters:

keysArbitrary - The arbitrary to generate the keys

valuesArbitrary - The arbitrary to generate the values

Returns:

a new arbitrary instance

entries

@API(status=MAINTAINED,
     since="1.2.0")
public static <K,V> Arbitrary<java.util.Map.Entry<K,V>> entries(Arbitrary<K> keysArbitrary,
                                                                            Arbitrary<V> valuesArbitrary)

Create an arbitrary to create instances of Map.Entry. The generated entries are mutable.

Type Parameters:

K - type of keys

V - type of values

Parameters:

keysArbitrary - The arbitrary to generate the keys

valuesArbitrary - The arbitrary to generate the values

Returns:

a new arbitrary instance

nothing

@API(status=MAINTAINED,
     since="1.3.0")
public static Arbitrary<java.lang.Void> nothing()

Create an arbitrary that never creates anything. Sometimes useful when generating arbitraries of "functions" that have void as return type.

Returns:

arbitrary instance that will generate nothing

subsetOf

@API(status=EXPERIMENTAL,
     since="1.6.4")
public static <T> SetArbitrary<T> subsetOf(java.util.Collection<T> values)

Create a new arbitrary of element type Set<T> using the handed in values as elements of the set.

Returns:

a new arbitrary instance

subsetOf

@API(status=EXPERIMENTAL,
     since="1.6.4")
public static <T> SetArbitrary<T> subsetOf(T... values)

Create a new arbitrary of element type Set<T> using the handed in values as elements of the set.

Returns:

a new arbitrary instance