ocaml alcotest example

test.ml

(*
utop # Alcotest.check Alcotest.string "foo" "abc" "abc";;
ASSERT foo
- : unit = ()
 *)

(* A module with functions to test *)
module To_test = struct
  let lowercase = String.lowercase_ascii
  let list_concat = List.append
end

(* The tests *)
let test_lowercase () =
  Alcotest.(check string) "same string" "hello!" (To_test.lowercase "hElLO!")

let test_list_concat () =
  Alcotest.(check (list int)) "same lists" [1; 2; 3] (To_test.list_concat [1] [2; 3])

(* Run it *)
let () =
  let open Alcotest in
  run "test module" [
    "string-case", [
      test_case "Lower case" `Quick test_lowercase
    ];
    "list-concat", [
      test_case "List mashing" `Slow test_list_concat
    ]
  ]
;;

(*
Testing `test module'.
This run has ID `22D39A4E-CE5C-4FE4-BA92-A2B0F6CA5CCD'.

  [OK]          string-case          0   Lower case.
  [OK]          list-concat          0   List mashing.

Full test results in `~/_build/_tests/test module'.
Test Successful in 0.000s. 2 tests run.
 *)