(*
copyright (c) 2013, simon cruanes
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(** {6 Quickcheck inspired property-based testing} *)

(** {2 Description of how to generate arbitrary values for some type} *)

module Arbitrary : sig
  type 'a t = Random.State.t -> 'a
    (** A generator of arbitrary values of type 'a *)

  val int : int -> int t
    (** Any integer *)

  val int_range : start:int -> stop:int -> int t
    (* Integer range *)

  val small_int : int t
    (** Ints lower than 100 *)

  val bool : bool t
    (** Arbitrary boolean *)

  val char : char t
    (** A (printable) char *)

  val alpha : char t
    (** Alphabetic char *)

  val float : float -> float t
    (** Random float *)

  val string : string t
    (** Random strings of small length *)

  val string_len : int t -> string t
    (** String of random length *)

  val map : 'a t -> ('a -> 'b) -> 'b t
    (** Transform an arbitrary into another *)

  val list : ?len:int t -> 'a t -> 'a list t
    (** List of arbitrary length *)

  val opt : 'a t -> 'a option t
    (** May return a value, or None *)

  val list_repeat : int -> 'a t -> 'a list t
    (** Lists of given length exactly *)

  val array : ?len:int t -> 'a t -> 'a array t
    (** Random array of random length *)

  val array_repeat : int -> 'a t -> 'a array t
    (** Random array of given length *)

  val among : 'a list -> 'a t
    (** Choose an element among those of the list *)

  val among_array : 'a array -> 'a t
    (** Choose in the array *)

  val among_tbl : ('k, 'v) Hashtbl.t -> 'v t
    (** Choose in the table *)

  val choose : 'a t list -> 'a t
    (** Choice among combinations *)

  val fix : ?max:int -> base:'a t -> ('a -> 'a t) -> 'a t
    (** Recursive arbitrary values. The optional value [max] defines
        the maximal depth, if needed. [base] is the base case. *)

  val fix_depth : depth:int t -> base:'a t -> ('a -> 'a t) -> 'a t
    (** Recursive values of at most given random depth *)
end

(** {2 Pretty printing} *)

module PP : sig
  type 'a t = 'a -> string

  val int : int t
  val bool : bool t
  val float : float t
  val char : char t
  val string : string t

  val list : 'a t -> 'a list t
  val array : 'a t -> 'a array t
end

(** {2 Testing} *)

module Prop : sig
  type 'a t = 'a -> bool

  val (==>) : ('a -> bool) -> 'a t -> 'a t
    (** Precondition for a test *)

  val (&&&) : 'a t -> 'a t -> 'a t
    (** Logical 'and' on tests *)

  val (|||) : 'a t -> 'a t -> 'a t
    (** Logical 'or' on tests *)

  val (!!!) : 'a t -> 'a t
    (** Logical 'not' on tests *)
end

type 'a result =
  | Ok of int * int  (** total number of tests / number of failed preconditions *)
  | Failed of 'a list
  | Error of exn

val check : ?rand:Random.State.t -> ?n:int -> 
            'a Arbitrary.t -> 'a Prop.t -> 'a result
  (** Check that the property [prop] holds on [n] random instances of the type
      'a, as generated by the arbitrary instance [gen] *)

(** {2 Main} *)

val run : ?pp:('a -> string) -> ?n:int ->
          ?rand:Random.State.t -> ?name:string ->
          'a Arbitrary.t -> 'a Prop.t -> bool
  (** Run and print result *)

val run_tests : (rand:Random.State.t -> bool) list -> bool
  (** Run a list of tests, and print their results *)