diff --git a/tests/core/dune b/tests/core/dune
new file mode 100644
index 00000000..b05279c4
--- /dev/null
+++ b/tests/core/dune
@@ -0,0 +1,5 @@
+(test
+ (name t)
+ (flags :standard -strict-sequence -warn-error -a+8 -open
+   Containers_testlib.Prelude)
+ (libraries containers containers_testlib))
diff --git a/tests/core/t.ml b/tests/core/t.ml
new file mode 100644
index 00000000..a42fcdbd
--- /dev/null
+++ b/tests/core/t.ml
@@ -0,0 +1,4 @@
+
+include T_list ;;
+
+Containers_testlib.run_all ~descr:"containers" ();;
diff --git a/tests/core/t_list.ml b/tests/core/t_list.ml
new file mode 100644
index 00000000..ef894c6b
--- /dev/null
+++ b/tests/core/t_list.ml
@@ -0,0 +1,307 @@
+
+open CCList
+
+let lsort l = CCList.sort Stdlib.compare l;;
+
+q ~__FILE__ ~__LINE__
+  Q.(pair small_nat (list int)) (fun (i,l) ->
+  nth_opt l i = get_at_idx i l);;
+
+q ~__FILE__ ~__LINE__
+  Q.(pair (list int) (list int)) (fun (l1,l2) ->
+  CCOrd.equiv (CCList.compare_lengths l1 l2)
+  (CCInt.compare (length l1)(length l2)));;
+
+q ~__FILE__ ~__LINE__
+  Q.(pair (list int) small_int) (fun (l,n) ->
+    CCOrd.equiv (CCList.compare_length_with l n)
+  (CCInt.compare (length l) n));;
+
+q ~__FILE__ ~__LINE__
+  (Q.list Q.small_int) (fun l ->
+    let f x = x+1 in
+    List.rev (List.rev_map f l) = map f l);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  [1;2;3] @ [4;5;6] = [1;2;3;4;5;6];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (1-- 10_000) @ (10_001 -- 20_000) = 1 -- 20_000;;
+
+q ~__FILE__ ~__LINE__
+  Q.(small_list int)(fun l -> List.rev l = List.fold_left cons' [] l);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  cons_maybe (Some 1) [2;3] = [1;2;3];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  cons_maybe None [2;3] = [2;3];;
+
+eq ~__FILE__ ~__LINE__ ~printer:CCInt.to_string
+  500 (filter (fun x->x mod 2 = 0) (1 -- 1000) |> List.length);;
+
+eq ~__FILE__ ~__LINE__ ~printer:CCInt.to_string
+  50_000 (filter (fun x->x mod 2 = 0) (1 -- 100_000) |> List.length);;
+
+eq ~__FILE__ ~__LINE__ ~printer:CCInt.to_string
+  500_000 (filter (fun x->x mod 2 = 0) (1 -- 1_000_000) |> List.length);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  fold_right (+) (1 -- 1_000_000) 0 =
+    List.fold_left (+) 0 (1 -- 1_000_000);;
+
+q ~__FILE__ ~__LINE__
+  (Q.list Q.small_int) (fun l ->
+    l = fold_right (fun x y->x::y) l []);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  fold_while (fun acc b -> if b then acc+1, `Continue else acc, `Stop)
+    0 [true;true;false;true] = 2 ;;
+
+eq ~__FILE__ ~__LINE__
+  (6, ["1"; "2"; "3"])
+    (fold_map (fun acc x->acc+x, string_of_int x) 0 [1;2;3]);;
+
+q ~__FILE__ ~__LINE__
+  Q.(list int) (fun l ->
+    fold_map (fun acc x -> x::acc, x) [] l = (List.rev l, l));;
+
+eq ~__FILE__ ~__LINE__
+  6 (fold_on_map ~f:int_of_string ~reduce:(+) 0 ["1";"2";"3"]);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(option int)
+  (Some 15) (reduce (+) [1; 2; 3; 4; 5]);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(option int)
+  (Some 3) (reduce CCInt.min [5; 3; 8; 9]);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.string
+  "hello world" (reduce_exn (^) ["hello"; " "; "world"]);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  try ignore (reduce_exn (+.) []); false with Invalid_argument _ -> true;;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(list int)
+  [0;1;3;6] (scan_left (+) 0 [1;2;3]);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(list int)
+  [0] (scan_left (+) 0 []);;
+
+q ~__FILE__ ~__LINE__
+  Q.(list int) (fun l -> 
+    List.length l + 1 = List.length (scan_left (+) 0 l));;
+
+eq ~__FILE__ ~__LINE__
+  (310, ["1 10"; "2 0"; "3 100"]) 
+    (fold_map2 (fun acc x y->acc+x*y, string_of_int x ^ " " ^ string_of_int y) 
+    0 [1;2;3] [10;0;100]);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (try ignore (fold_map2 (fun _ _ _ -> assert false) 42 [] [1]); false 
+  with Invalid_argument _ -> true);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(pair int (list int))
+  (List.fold_left (+) 0 (1--10), [2;4;6;8;10])
+  (fold_filter_map (fun acc x -> acc+x, if x mod 2 = 0 then Some x else None)
+  0 (1--10));;
+
+eq ~__FILE__ ~__LINE__
+  (6, ["1"; "a1"; "2"; "a2"; "3"; "a3"]) 
+    (let pf = Printf.sprintf in 
+    fold_flat_map (fun acc x->acc+x, [pf "%d" x; pf "a%d" x]) 0 [1;2;3]);;
+
+q ~__FILE__ ~__LINE__
+  Q.(list int) (fun l -> 
+    fold_flat_map (fun acc x -> x::acc, [x;x+10]) [] l = 
+      (List.rev l, flat_map (fun x->[x;x+10]) l) );;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  init 0 (fun _ -> 0) = [];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  init 1 (fun x->x) = [0];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  init 1000 (fun x->x) = 0--999;;
+
+(* see: #256 *)
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  let r = ref [] in
+  ignore (CCList.init 5 (fun x -> r := x :: !r; ()));
+  assert_equal ~printer:Q.Print.(list int) (List.rev !r) [0;1;2;3;4];
+  true;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  let r = ref [] in
+  ignore (CCList.init 200_000 (fun x -> r := x :: !r; ()));
+  assert_equal ~printer:Q.Print.(list int) (List.rev !r) (0--(200_000-1));
+  true ;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  equal CCInt.equal (1--1_000_000) (1--1_000_000);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  flat_map (fun x -> [x+1; x*2]) [10;100] = [11;20;101;200];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  List.length (flat_map (fun x->[x]) (1--300_000)) = 300_000;;
+
+eq ~__FILE__ ~__LINE__
+  [1;2;2;3;3;3] (flat_map_i (fun i x->replicate (i+1) x) [1;2;3]);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  flatten [[1]; [2;3;4]; []; []; [5;6]] = 1--6;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  flatten (init 300_001 (fun x->[x])) = 0--300_000;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count (fun x -> x mod 2 = 0) [] = 0;;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count (fun x -> x mod 2 = 0) [0; 0; 2; 4] = 4;;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count (fun x -> x mod 2 = 0) [1; 3; 5; 7] = 0;;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count (fun x -> x mod 2 = 0) [2; 6; 9; 4] = 3;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count_true_false (fun x -> x mod 2 = 0) [] = (0, 0);;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count_true_false (fun x -> x mod 2 = 0) [0; 0; 2; 4] = (4, 0);;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count_true_false (fun x -> x mod 2 = 0) [1; 3; 5; 7] = (0, 4);;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  count_true_false (fun x -> x mod 2 = 0) [2; 6; 9; 4] = (3, 1);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  diagonal [] = [];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  diagonal [1] = [];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  diagonal [1;2] = [1,2];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  diagonal [1;2;3] |> List.sort Stdlib.compare = [1, 2; 1, 3; 2, 3];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  let l1, l2 =
+    partition_map_either (function
+      | n when n mod 2 = 0 -> CCEither.Left n
+      | n -> CCEither.Right n
+    ) [0;1;2;3;4]
+  in
+  assert_equal [0;2;4] l1;
+  assert_equal [1;3] l2;
+  true;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  let l1, l2 =
+    partition_filter_map (function
+      | n when n = 0 -> `Drop
+      | n when n mod 2 = 0 -> `Left n
+      | n -> `Right n
+    ) [0;1;2;3;4]
+  in
+  assert_equal [2;4] l1;
+  assert_equal [1;3] l2;
+  true;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  try ignore (combine [1] []); false with Invalid_argument _ -> true;;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  try ignore (combine (1--1001) (1--1002)); false with Invalid_argument _ -> true;;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  combine [1;2;3] [3;2;1] = List.combine [1;2;3] [3;2;1];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  combine (1 -- 100_000) (1 -- 100_000) = List.combine (1 -- 100_000) (1 -- 100_000);;
+
+q ~__FILE__ ~__LINE__
+  Q.(let p = small_list int in pair p p)(fun (l1,l2) -> 
+    if List.length l1=List.length l2 
+    then CCList.combine l1 l2 = List.combine l1 l2 
+    else Q.assume_fail() );;
+
+q ~__FILE__ ~__LINE__
+  Q.(let p = small_list int in pair p p)(fun (l1,l2) -> 
+    let n = min (List.length l1) (List.length l2) in 
+    let res1 = combine (take n l1) (take n l2) in 
+    let res2 = combine_gen l1 l2 |> of_gen in 
+    res1 = res2);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (combine_shortest [] []) = [];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (combine_shortest [1] []) = [];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (combine_shortest [] [1]) = [];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (combine_shortest (1--1025) (1--1026)) = List.combine (1--1025) (1--1025);;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  (combine_shortest (1--1026) (1--1025)) = List.combine (1--1025) (1--1025);;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  combine_shortest [1;2;3] [3;2;1] = List.combine [1;2;3] [3;2;1];;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  combine_shortest (1 -- 100_000) (1 -- 100_000) = List.combine (1 -- 100_000) (1 -- 100_000);;
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  combine_shortest (1 -- 100_001) (1 -- 100_000) = List.combine (1 -- 100_000) (1 -- 100_000);;
+
+q ~__FILE__ ~__LINE__
+  (Q.(list_of_size Gen.(0--10_000) (pair small_int small_string))) (fun l -> 
+    let (l1, l2) = split l in 
+    List.length l1 = List.length l 
+    && List.length l2 = List.length l);;
+
+q ~__FILE__ ~__LINE__ 
+  Q.(list_of_size Gen.(0--10_000) (pair small_int small_int)) (fun l -> 
+    split l = List.split l);;
+
+let cmp_lii_unord l1 l2 : bool =
+  List.sort CCOrd.compare l1 = List.sort CCOrd.compare l2;;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(list (list int)) ~cmp:cmp_lii_unord
+  [[1;3;4];[1;3;5];[1;3;6];[2;3;4];[2;3;5];[2;3;6]] 
+    (cartesian_product [[1;2];[3];[4;5;6]]);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(list (list int)) ~cmp:cmp_lii_unord
+  [] (cartesian_product [[1;2];[];[4;5;6]]);
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(list (list int)) ~cmp:cmp_lii_unord
+  [[]] (cartesian_product []);;
+
+eq ~__FILE__ ~__LINE__
+  ~printer:Q.Print.(list (list int)) ~cmp:cmp_lii_unord
+  [[1;3;4;5;6];[2;3;4;5;6]] 
+    (cartesian_product [[1;2];[3];[4];[5];[6]]);;
+
+q ~__FILE__ ~__LINE__ 
+  Q.(list_of_size Gen.(1--4) (list_of_size Gen.(0--4) small_int)) (fun l-> 
+    cmp_lii_unord (cartesian_product l) (map_product_l CCFun.id l));;
+
+q ~__FILE__ ~__LINE__
+  Q.(pair small_int (list small_int)) (fun (x,l) -> 
+    sorted_mem ~cmp:CCInt.compare x (List.sort CCInt.compare l) = mem ~eq:CCInt.equal x l) ;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  equal CCInt.equal (List.sort CCInt.compare ([(( * )2); ((+)1)] <*> [10;100])) 
+    [11; 20; 101; 200] ;;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  equal CCInt.equal (sorted_merge ~cmp:CCInt.compare [1;1;2] [1;2;3]) [1;1;1;2;2;3] ;;
+
+q ~__FILE__ ~__LINE__
+  Q.(pair (list int) (list int)) (fun (l1,l2) -> 
+    List.length (sorted_merge ~cmp:CCInt.compare l1 l2) = List.length l1 + List.length l2);;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  equal CCInt.equal (sorted_diff ~cmp:CCInt.compare [0;1;1;2;4] [1;2;2;2;3]) [0;1;4];;
+
+t ~__FILE__ ~__LINE__ @@ fun () ->
+  equal CCInt.equal (sorted_diff ~cmp:CCInt.compare [2] [1;2;2;2;3]) [];;