arbitrary(+Type, -Value) is det[multifile]

Generate a random Value of Type. If you define your own types, add clauses to this multifile predicate to support them in quickcheck. When defining your own types, it can be helpful to call arbitrary/2 recursively or to use library(random).

The following types from library(error) have built in support.

• any
• atom
• atomic
• between(L,U)
• boolean
• chars
• code - printable ASCII for now
• codes
• encoding
• float
• integer
• list
• list(T)
• negative_integer
• `nonneg alias natural`
• number
• oneof(L)
• positive_integer
• rational
• string
• text

 shrink(+Type, +Value, -Smaller) is nondet[multifile]

True if Smaller is a "smaller" version of Value according to the semantics of Type. This predicate is called after quickcheck finds a Value for which a property fails. By recursively shrinking values, we can obtain a minimal, failing example.

When defining shrink/3 for your own types, be sure to fail if Value cannot be shrunk any smaller. It's acceptable to produce additional shrunken values on backtracking. It's often best to bisect your type's values (rather than iterating all possible, smaller values) if bisecting makes for your type.

 composite(+Type, +Arbitrary:BaseType, -Value) is det[multifile]

Generate a random Value of Type from a given Arbitrary.

 quickcheck(+Property:atom) is semidet

True if Property holds for many random values. Property should be a Name/Arity term. Details about test results are displayed on the user_error stream.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 arbitrary_type(Arg1)