package ppx_deriving_qcheck

ppx_deriving_qcheck

Documentation

The documentation can be found here.

Arbitrary

Derive QCheck.arbitrary on a type declaration

type tree = Leaf of int | Node of tree * tree
[@@deriving arb]

Overwrite arbitrary

If you wan't to specify your own arbitrary for any type you can add an attribute to the type:

type t = (int : [@arb QCheck.(0 -- 10)])
[@@deriving arb]

(* produces *)

let arb : t QCheck.arbitrary = QCheck.(0 -- 10)

This attribute has 2 advantages:

• Use your own arbitrary for a specific type (see above)

• Arbitrary is not available for a type

  type my_foo =
  | Foo of my_other_type
  | Bar of bool
  [@@deriving arb]
  ^^^^^^^^^^^^^^^^
  Error: Unbound value arb_my_other_type
    
  (* Possible fix *)
  let arb_my_other_type = (* add your implementation here *)
    
  type my_foo =
  | Foo of my_other_type [@arb arb_my_other_type]
  | Bar of bool
  [@@deriving arb]
  

How to use

Install ppx_deriving_qcheck (dev version)

$ opam pin add ppx_deriving_qcheck.dev git+https://github.com/vch9/ppx_deriving_qcheck.git#dev

Add to your OCaml libraries with dune

...
(libraries ppx_deriving_qcheck)
(preprocess (pps ppx_deriving_qcheck)))
...