package qtest

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package qtest
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val (==>) : bool -> bool -> bool

b1 ==> b2 is the logical implication b1 => b2 ie not b1 || b2 (except that it is strict).

module Gen : sig ... end
module Print : sig ... end
module Iter : sig ... end
module Shrink : sig ... end
type 'a arbitrary = {
  1. gen : 'a Gen.t;
  2. print : ('a -> string) option;
    (*

    print values

    *)
  3. small : ('a -> int) option;
    (*

    size of example

    *)
  4. shrink : 'a Shrink.t option;
    (*

    shrink to smaller examples

    *)
  5. collect : ('a -> string) option;
    (*

    map value to tag, and group by tag

    *)
}

a value of type 'a arbitrary is an object with a method for generating random values of type 'a, and additional methods to compute the size of values, print them, and possibly shrink them into smaller counterexamples

val make : ?print:'a Print.t -> ?small:('a -> int) -> ?shrink:'a Shrink.t -> ?collect:('a -> string) -> 'a Gen.t -> 'a arbitrary

Builder for arbitrary. Default is to only have a generator, but other arguments can be added

val set_print : 'a Print.t -> 'a arbitrary -> 'a arbitrary
val set_small : ('a -> int) -> 'a arbitrary -> 'a arbitrary
val set_shrink : 'a Shrink.t -> 'a arbitrary -> 'a arbitrary
val set_collect : ('a -> string) -> 'a arbitrary -> 'a arbitrary
val choose : 'a arbitrary list -> 'a arbitrary

Choose among the given list of generators. The list must not be empty; if it is Invalid_argument is raised.

val unit : unit arbitrary

always generates (), obviously.

val bool : bool arbitrary

uniform boolean generator

val float : float arbitrary

generates regular floats (no nan and no infinities)

val pos_float : float arbitrary

positive float generator (no nan and no infinities)

val neg_float : float arbitrary

negative float generator (no nan and no infinities)

val int : int arbitrary

int generator. Uniformly distributed

val int_bound : int -> int arbitrary

int_bound n is uniform between 0 and n included

val int_range : int -> int -> int arbitrary

int_range a b is uniform between a and b included. b must be larger than a.

val (--) : int -> int -> int arbitrary

Synonym to int_range

val int32 : int32 arbitrary

int32 generator. Uniformly distributed

val int64 : int64 arbitrary

int generator. Uniformly distributed

val pos_int : int arbitrary

positive int generator. Uniformly distributed

val small_int : int arbitrary

positive int generator. The probability that a number is chosen is roughly an exponentially decreasing function of the number.

val small_int_corners : unit -> int arbitrary

As small_int, but each newly created generator starts with a list of corner cases before falling back on random generation.

val neg_int : int arbitrary

negative int generator. The distribution is similar to that of small_int, not of pos_int.

val char : char arbitrary

Uniformly distributed on all the chars (not just ascii or valid latin-1)

val printable_char : char arbitrary

uniformly distributed over a subset of chars

val numeral_char : char arbitrary

uniformy distributed over '0'..'9'

val string_gen_of_size : int Gen.t -> char Gen.t -> string arbitrary
val string_gen : char Gen.t -> string arbitrary

generates strings with a distribution of length of small_int

val string : string arbitrary

generates strings with a distribution of length of small_int and distribution of characters of char

val string_of_size : int Gen.t -> string arbitrary

generates strings with distribution of characters if char

val printable_string : string arbitrary

generates strings with a distribution of length of small_int and distribution of characters of printable_char

val printable_string_of_size : int Gen.t -> string arbitrary

generates strings with distribution of characters of printable_char

val numeral_string : string arbitrary

generates strings with a distribution of length of small_int and distribution of characters of numeral_char

val numeral_string_of_size : int Gen.t -> string arbitrary

generates strings with a distribution of characters of numeral_char

val list : 'a arbitrary -> 'a list arbitrary

generates lists with length generated by small_int

val list_of_size : int Gen.t -> 'a arbitrary -> 'a list arbitrary

generates lists with length from the given distribution

val array : 'a arbitrary -> 'a array arbitrary

generates arrays with length generated by small_int

val array_of_size : int Gen.t -> 'a arbitrary -> 'a array arbitrary

generates arrays with length from the given distribution

val pair : 'a arbitrary -> 'b arbitrary -> ('a * 'b) arbitrary

combines two generators into a generator of pairs

val triple : 'a arbitrary -> 'b arbitrary -> 'c arbitrary -> ('a * 'b * 'c) arbitrary

combines three generators into a generator of 3-uples

val option : 'a arbitrary -> 'a option arbitrary

choose between returning Some random value, or None

val fun1 : 'a arbitrary -> 'b arbitrary -> ('a -> 'b) arbitrary

generator of functions of arity 1. The functions are always pure and total functions:

  • when given the same argument (as decided by Pervasives.(=)), it returns the same value
  • it never does side effects, like printing or never raise exceptions etc. The functions generated are really printable.
val fun2 : 'a arbitrary -> 'b arbitrary -> 'c arbitrary -> ('a -> 'b -> 'c) arbitrary

generator of functions of arity 2. The remark about fun1 also apply here.

val oneofl : ?print:'a Print.t -> ?collect:('a -> string) -> 'a list -> 'a arbitrary

Pick an element randomly in the list

val oneof : 'a arbitrary list -> 'a arbitrary

Pick a generator among the list, randomly

val always : ?print:'a Print.t -> 'a -> 'a arbitrary

Always return the same element

val frequency : ?print:'a Print.t -> ?small:('a -> int) -> ?shrink:'a Shrink.t -> ?collect:('a -> string) -> (int * 'a arbitrary) list -> 'a arbitrary

Similar to oneof but with frequencies

val frequencyl : ?print:'a Print.t -> ?small:('a -> int) -> (int * 'a) list -> 'a arbitrary

Same as oneofl, but each element is paired with its frequency in the probability distribution (the higher, the more likely)

val map : ?rev:('b -> 'a) -> ('a -> 'b) -> 'a arbitrary -> 'b arbitrary

map f a returns a new arbitrary instance that generates values using a#gen and then transforms them through f.

  • parameter rev

    if provided, maps values back to type 'a so that the printer, shrinker, etc. of a can be used

val map_same_type : ('a -> 'a) -> 'a arbitrary -> 'a arbitrary

Specialization of map when the transformation preserves the type, which makes shrinker, printer, etc. still relevant

val verbose : bool Pervasives.ref

Default is false, but if true, random tests will print statistics on their set of inputs

val laws_exn : ?small:('a -> int) -> ?count:int -> ?max_gen:int -> ?max_fail:int -> string -> 'a arbitrary -> ('a -> bool) -> Random.State.t -> unit

laws_exn ?small ?count name arbitrary law st generates up to count random values of type 'a with using arbitrary and the random state st. The predicate law is called on them and if it returns false or raises an exception then we have a counter example for the law.

  • parameter small

    kept for compatibility reasons; if provided, replaces the field arbitrary.small.

  • parameter max_gen

    maximum number of times the generation function is called to replace inputs that do not satisfy preconditions

  • parameter max_fail

    maximum number of failures before we stop generating inputs. This is useful if shrinking takes too much time.

  • raises Failure

    if a counter example has been found, containing the stringified example