alcotest

Alcotest is a lightweight and colourful test framework
Library alcotest.engine
val tag : [ `Ok | `Fail | `Skip | `Todo | `Assert ] Fmt.t
val map_theta : ( Format.formatter -> unit ) -> f:( unit Fmt.t -> unit Fmt.t ) -> Format.formatter -> unit
val pp_plural : int Fmt.t

This is for adding an 's' to words that should be pluralized, e.g.

let n = List.length items in
Fmt.pr "Found %i item%a." n pp_plural n
module Make (X : sig ... end) : sig ... end