module Main = struct
    open OUnit2

    (* Program start *)

    (* Program end *)

    (* Test cases *)
    
let test1 _ = assert_equal "135" (digitSum "11111222223" 3)

let test2 _ = assert_equal "000" (digitSum "00000000" 3)

let test3 _ = assert_equal "0" (digitSum "0" 2)

let test4 _ = assert_equal "59" (digitSum "6421145198777362190042394610980120758216614468524308044135603727111584866360410865574469873746173533" 2)

let test5 _ = assert_equal "6828549665923521139586766197204369524222360091033439842730341293447277906510091763414462467630345859" (digitSum "6828549665923521139586766197204369524222360091033439842730341293447277906510091763414462467630345859" 100)

let test6 _ = assert_equal "60414742559" (digitSum "86835675433222437140367269363341651026820150582311446699662136" 12)

let test7 _ = assert_equal "228109" (digitSum "09556959624863822113055328888211114768861024488160715110957533476207255541787" 52)

let test8 _ = assert_equal "18315" (digitSum "33628763334261975447998353546830413109540456" 40)

let test9 _ = assert_equal "10632" (digitSum "4261628821970427731371304870116953" 26)

let test10 _ = assert_equal "3219" (digitSum "6260198388" 7)


    (* Grouping test cases *)
    let suite = "Test Suite for digitSum" >::: [
        
  "test1" >:: test1;
  "test2" >:: test2;
  "test3" >:: test3;
  "test4" >:: test4;
  "test5" >:: test5;
  "test6" >:: test6;
  "test7" >:: test7;
  "test8" >:: test8;
  "test9" >:: test9;
  "test10" >:: test10;
    ]


    (* Running the tests *)
    let () = run_test_tt_main suite
end