diff --git a/lib/tests/dune.inc b/lib/tests/dune.inc
index e219fc10e..b16a266b6 100644
--- a/lib/tests/dune.inc
+++ b/lib/tests/dune.inc
@@ -32,13 +32,23 @@
 (library
  ;; lib/tests/test_fun_call.ml
  (name test_fun_call_75)
- (enabled_if (<> %{profile} using-effects))
+ (enabled_if (and (<> %{profile} using-effects) (<> %{profile} wasm) (<> %{profile} wasm-effects)))
  (modules test_fun_call)
  (libraries js_of_ocaml unix)
  (inline_tests (modes js))
  (preprocess
   (pps ppx_js_internal ppx_expect)))
 
+(library
+ ;; lib/tests/test_fun_call_2.ml
+ (name test_fun_call_2_75)
+ (enabled_if true)
+ (modules test_fun_call_2)
+ (libraries js_of_ocaml unix)
+ (inline_tests (modes js))
+ (preprocess
+  (pps ppx_js_internal ppx_expect)))
+
 (library
  ;; lib/tests/test_json.ml
  (name test_json_75)
@@ -62,13 +72,23 @@
 (library
  ;; lib/tests/test_poly_compare.ml
  (name test_poly_compare_75)
- (enabled_if true)
+ (enabled_if (and (<> %{profile} wasm) (<> %{profile} wasm-effects)))
  (modules test_poly_compare)
  (libraries js_of_ocaml unix)
  (inline_tests (modes js))
  (preprocess
   (pps ppx_js_internal ppx_expect)))
 
+(library
+ ;; lib/tests/test_poly_equal.ml
+ (name test_poly_equal_75)
+ (enabled_if true)
+ (modules test_poly_equal)
+ (libraries js_of_ocaml unix)
+ (inline_tests (modes js))
+ (preprocess
+  (pps ppx_js_internal ppx_expect)))
+
 (library
  ;; lib/tests/test_regexp.ml
  (name test_regexp_75)
diff --git a/lib/tests/gen-rules/gen.ml b/lib/tests/gen-rules/gen.ml
index cc42105ce..eda5eea71 100644
--- a/lib/tests/gen-rules/gen.ml
+++ b/lib/tests/gen-rules/gen.ml
@@ -47,14 +47,14 @@ let prefix : string =
 
 type enabled_if =
   | GE5
-  | No_effects
   | Not_wasm
+  | No_effects_not_wasm
   | Any
 
 let enabled_if = function
   | "test_sys" -> GE5
-  | "test_fun_call" -> No_effects
-  | "test_json" -> Not_wasm
+  | "test_fun_call" -> No_effects_not_wasm
+  | "test_json" | "test_poly_compare" -> Not_wasm
   | _ -> Any
 
 let () =
@@ -85,6 +85,8 @@ let () =
                (* ZZZ /static not yet implemented *)
                "(and (>= %{ocaml_version} 5) (<> %{profile} wasm) (<> %{profile} \
                 wasm-effects))"
-           | No_effects -> "(<> %{profile} using-effects)"
-           | Not_wasm -> "(and (<> %{profile} wasm) (<> %{profile} wasm-effects))")
+           | Not_wasm -> "(and (<> %{profile} wasm) (<> %{profile} wasm-effects))"
+           | No_effects_not_wasm ->
+               "(and (<> %{profile} using-effects) (<> %{profile} wasm) (<> %{profile} \
+                wasm-effects))")
            basename)
diff --git a/lib/tests/test_fun_call.ml b/lib/tests/test_fun_call.ml
index f36b0b871..888246dd2 100644
--- a/lib/tests/test_fun_call.ml
+++ b/lib/tests/test_fun_call.ml
@@ -29,8 +29,9 @@ let s x =
       return "undefined"
     if(typeof x === "function")
       return "function#" + x.length + "#" + x.l
-    if (x.toString) return x.toString();
-    return "other"
+    if(x.toString() == "[object Arguments]")
+      return "(Arguments: " + Array.prototype.slice.call(x).toString() + ")";
+    return x.toString()
 })
 |}
   in
@@ -146,7 +147,7 @@ let%expect_test "wrap_callback_strict" =
     (Js.Unsafe.callback_with_arity 2 cb3)
     {| (function(f){ return f(1,2,3) }) |};
   [%expect {|
-    Result: other |}];
+    Result: function#1#1 |}];
   call_and_log
     (Js.Unsafe.callback_with_arity 2 cb3)
     ~cont:(fun g -> g 4)
@@ -163,7 +164,7 @@ let%expect_test "wrap_callback_strict" =
     Result: 0 |}];
   call_and_log (Js.Unsafe.callback_with_arity 2 cb3) {| (function(f){ return f(1,2) }) |};
   [%expect {|
-    Result: other |}]
+    Result: function#1#1 |}]
 
 let%expect_test "wrap_callback_strict" =
   call_and_log
@@ -290,7 +291,7 @@ let%expect_test "wrap_meth_callback_strict" =
     (Js.Unsafe.meth_callback_with_arity 2 cb4)
     {| (function(f){ return f.apply("this",[1,2,3]) }) |};
   [%expect {|
-    Result: other |}];
+    Result: function#1#1 |}];
   call_and_log
     (Js.Unsafe.meth_callback_with_arity 2 cb4)
     ~cont:(fun g -> g 4)
@@ -308,7 +309,7 @@ let%expect_test "wrap_meth_callback_strict" =
   call_and_log
     (Js.Unsafe.meth_callback_with_arity 2 cb4)
     {| (function(f){ return f.apply("this",[1,2]) }) |};
-  [%expect {| Result: other |}]
+  [%expect {| Result: function#1#1 |}]
 
 let%expect_test "wrap_meth_callback_strict" =
   call_and_log
@@ -353,15 +354,13 @@ let%expect_test "partial application, extra arguments set to undefined" =
 let%expect_test _ =
   call_and_log cb3 ~cont:(fun g -> g 1) {| (function(f){ return f }) |};
   [%expect {|
-    Result: other |}]
+    Result: function#2#2 |}]
 
-(*
 let%expect_test _ =
   call_and_log cb3 ~cont:(fun g -> g 1 2 3 4) {| (function(f){ return f }) |};
   [%expect {|
     got 1, 2, 3, done
     Result: 0 |}]
-*)
 
 let%expect_test _ =
   let f cb =
@@ -370,17 +369,15 @@ let%expect_test _ =
     | _ -> Printf.printf "Error: unknown"
   in
   f cb5;
-  [%expect {| Result: other |}];
+  [%expect {| Result: function#1#1 |}];
   f cb4;
   [%expect {|
     got 1, 1, 2, 3, done
     Result: 0 |}];
-  ()
-(* f cb3;
-   [%expect {|
-     got 1, 1, 2, done
-     Result: 0 |}]
-*)
+  f cb3;
+  [%expect {|
+    got 1, 1, 2, done
+    Result: 0 |}]
 
 let%expect_test _ =
   let f cb =
@@ -388,7 +385,6 @@ let%expect_test _ =
     | Invalid_argument s | Failure s -> Printf.printf "Error: %s" s
     | _ -> Printf.printf "Error: unknown"
   in
-  (*
   f (Obj.magic cb1);
   [%expect {|
     got 1, done
@@ -397,21 +393,20 @@ let%expect_test _ =
   [%expect {|
     got 1, 2, done
     Result: 0 |}];
-*)
   f (Obj.magic cb3);
   [%expect {|
     got 1, 2, 3, done
     Result: 0 |}];
   f (Obj.magic cb4);
   [%expect {|
-    Result: other |}];
+    Result: function#1#1 |}];
   f (Obj.magic cb5);
   [%expect {|
-    Result: other |}]
+    Result: function#2#2 |}]
 
 let%expect_test _ =
   let open Js_of_ocaml in
-  let f = Js.wrap_callback (fun s -> print_endline (Js.to_string s)) in
+  let f = Js.wrap_callback (fun s -> print_endline s) in
   Js.export "f" f;
   let () =
     Js.Unsafe.fun_call
diff --git a/lib/tests/test_fun_call_2.ml b/lib/tests/test_fun_call_2.ml
new file mode 100644
index 000000000..1a8dd0071
--- /dev/null
+++ b/lib/tests/test_fun_call_2.ml
@@ -0,0 +1,420 @@
+(* Js_of_ocaml tests
+ * http://www.ocsigen.org/js_of_ocaml/
+ * Copyright (C) 2020 Hugo Heuzard
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, with linking exception;
+ * either version 2.1 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *)
+open Js_of_ocaml
+
+let s x =
+  let to_string =
+    Js.Unsafe.eval_string
+      {|
+(function(x){
+    if(x === null)
+      return "null"
+    if(x === undefined)
+      return "undefined"
+    if (!(typeof x == 'function') && x.toString) return x.toString();
+    return "other"
+})
+|}
+  in
+  Js.to_string (Js.Unsafe.fun_call to_string [| Js.Unsafe.inject x |])
+
+let call_and_log f ?(cont = (Obj.magic Fun.id : _ -> _)) str =
+  let call = Js.Unsafe.eval_string str in
+  let r = Js.Unsafe.fun_call call [| Js.Unsafe.inject f |] in
+  Printf.printf "Result: %s" (s (cont r))
+
+let cb1 a = Printf.printf "got %s, done\n" (s a)
+
+let cb2 a b = Printf.printf "got %s, %s, done\n" (s a) (s b)
+
+let cb3 a b c = Printf.printf "got %s, %s, %s, done\n" (s a) (s b) (s c)
+
+let cb4 a b c d = Printf.printf "got %s, %s, %s, %s, done\n" (s a) (s b) (s c) (s d)
+
+let cb5 a b c d e =
+  Printf.printf "got %s, %s, %s, %s, %s, done\n" (s a) (s b) (s c) (s d) (s e)
+
+(* Wrap callback *)
+
+let%expect_test "over application, extra arguments are dropped" =
+  call_and_log (Js.wrap_callback cb3) {| (function(f){ return f(1,2,3,4) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "over application, extra arguments are dropped" =
+  call_and_log (Js.wrap_callback cb3) {| (function(f){ return f(1,2)(3,4) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application 1 + 2" =
+  call_and_log (Js.wrap_callback cb3) {| (function(f){ return f(1)(2,3) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application 2 + 1" =
+  call_and_log (Js.wrap_callback cb3) {| (function(f){ return f(1,2)(3) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application, callback is called when all arguments are available"
+    =
+  call_and_log (Js.wrap_callback cb5) {| (function(f){ return f(1)(2)(3)(4)(5) }) |};
+  [%expect {|
+    got 1, 2, 3, 4, 5, done
+    Result: 0 |}]
+
+let%expect_test "partial application, 0 argument call is treated like 1 argument \
+                 (undefined)" =
+  call_and_log (Js.wrap_callback cb5) {| (function(f){ return f(1)()(3)()(5) }) |};
+  [%expect {|
+    got 1, undefined, 3, undefined, 5, done
+    Result: 0 |}]
+
+let%expect_test _ =
+  let plus = Js.wrap_callback (fun a b -> a + b) in
+  call_and_log plus {| (function(f){ return f(1) }) |};
+  [%expect {| Result: other |}];
+  call_and_log plus {| (function(f){ return f(1)(2) }) |};
+  [%expect {| Result: 3 |}];
+  call_and_log plus {| (function(f){ return f(1,2) }) |};
+  [%expect {| Result: 3 |}];
+  call_and_log plus {| (function(f){ return f(1,2,3) }) |};
+  [%expect {| Result: 3 |}]
+
+(* Wrap callback with argument *)
+
+let%expect_test "wrap_callback_arguments" =
+  call_and_log
+    (Js.Unsafe.callback_with_arguments (Obj.magic cb1))
+    {| (function(f){ return f(1,2,3,4,5) }) |};
+  [%expect {|
+    got 1,2,3,4,5, done
+    Result: 0 |}]
+
+let%expect_test "wrap_callback_arguments" =
+  call_and_log
+    (Js.Unsafe.callback_with_arguments (Obj.magic cb1))
+    {| (function(f){ return f() }) |};
+  [%expect {|
+    got , done
+    Result: 0 |}]
+
+(* Wrap with arity *)
+
+let%expect_test "wrap_callback_strict" =
+  call_and_log
+    (Js.Unsafe.callback_with_arity 3 cb3)
+    {| (function(f){ return f(1,2,3) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.callback_with_arity 3 cb3)
+    {| (function(f){ return f(1,2,3,4) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log (Js.Unsafe.callback_with_arity 3 cb3) {| (function(f){ return f(1,2) }) |};
+  [%expect {|
+    got 1, 2, undefined, done
+    Result: 0 |}]
+
+let%expect_test "wrap_callback_strict" =
+  call_and_log
+    (Js.Unsafe.callback_with_arity 2 cb3)
+    {| (function(f){ return f(1,2,3) }) |};
+  [%expect {|
+    Result: other |}];
+  call_and_log
+    (Js.Unsafe.callback_with_arity 2 cb3)
+    ~cont:(fun g -> g 4)
+    {| (function(f){ return f(1,2,3) }) |};
+  [%expect {|
+    got 1, 2, 4, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.callback_with_arity 2 cb3)
+    ~cont:(fun g -> g 3)
+    {| (function(f){ return f(1,2) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log (Js.Unsafe.callback_with_arity 2 cb3) {| (function(f){ return f(1,2) }) |};
+  [%expect {|
+    Result: other |}]
+
+let%expect_test "wrap_callback_strict" =
+  call_and_log
+    (Js.Unsafe.callback_with_arity 4 cb3)
+    {| (function(f){ return f(1,2,3) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.callback_with_arity 4 cb3)
+    {| (function(f){ return f(1,2,3,4) }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log (Js.Unsafe.callback_with_arity 4 cb3) {| (function(f){ return f(1,2) }) |};
+  [%expect {|
+    got 1, 2, undefined, done
+    Result: 0 |}]
+
+(* Wrap meth callback *)
+
+let%expect_test "over application, extra arguments are dropped" =
+  call_and_log
+    (Js.wrap_meth_callback cb4)
+    {| (function(f){ return f.apply("this",[1,2,3,4]) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "over application, extra arguments are dropped" =
+  call_and_log
+    (Js.wrap_meth_callback cb4)
+    {| (function(f){ return f.apply("this",[1,2])(3,4) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application 1 + 2" =
+  call_and_log
+    (Js.wrap_meth_callback cb4)
+    {| (function(f){ return f.apply("this", [1])(2,3) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application 2 + 1" =
+  call_and_log
+    (Js.wrap_meth_callback cb4)
+    {| (function(f){ return f.apply("this",[1,2])(3) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application, callback is called when all arguments are available"
+    =
+  call_and_log
+    (Js.wrap_meth_callback cb5)
+    {| (function(f){ return f.apply("this",[])(1)(2)(3)(4) }) |};
+  [%expect {|
+    got this, 1, 2, 3, 4, done
+    Result: 0 |}]
+
+let%expect_test "partial application, 0 argument call is treated 1 argument (undefined)" =
+  call_and_log
+    (Js.wrap_meth_callback cb5)
+    {| (function(f){ return f.apply("this",[])(1)()(3)() }) |};
+  [%expect {|
+    got this, 1, undefined, 3, undefined, done
+    Result: 0 |}]
+
+let%expect_test _ =
+  let plus = Js.wrap_meth_callback (fun _ a b -> a + b) in
+  call_and_log plus {| (function(f){ return f(1) }) |};
+  [%expect {| Result: other |}];
+  call_and_log plus {| (function(f){ return f(1)(2) }) |};
+  [%expect {| Result: 3 |}];
+  call_and_log plus {| (function(f){ return f(1,2) }) |};
+  [%expect {| Result: 3 |}];
+  call_and_log plus {| (function(f){ return f(1,2,3) }) |};
+  [%expect {| Result: 3 |}]
+
+(* Wrap callback with argument *)
+
+let%expect_test "wrap_meth_callback_arguments" =
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arguments (Obj.magic cb2))
+    {| (function(f){ return f.apply("this",[1,2,3,4,5]) }) |};
+  [%expect {|
+    got this, 1,2,3,4,5, done
+    Result: 0 |}]
+
+let%expect_test "wrap_meth_callback_arguments" =
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arguments (Obj.magic cb2))
+    {| (function(f){ return f.apply("this", []) }) |};
+  [%expect {|
+    got this, , done
+    Result: 0 |}]
+
+(* Wrap with arity *)
+
+let%expect_test "wrap_meth_callback_strict" =
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 3 cb4)
+    {| (function(f){ return f.apply("this",[1,2,3]) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 3 cb4)
+    {| (function(f){ return f.apply("this",[1,2,3,4]) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 3 cb4)
+    {| (function(f){ return f.apply("this",[1,2]) }) |};
+  [%expect {|
+    got this, 1, 2, undefined, done
+    Result: 0 |}]
+
+let%expect_test "wrap_meth_callback_strict" =
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 2 cb4)
+    {| (function(f){ return f.apply("this",[1,2,3]) }) |};
+  [%expect {|
+    Result: other |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 2 cb4)
+    ~cont:(fun g -> g 4)
+    {| (function(f){ return f.apply("this",[1,2,3]) }) |};
+  [%expect {|
+    got this, 1, 2, 4, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 2 cb4)
+    ~cont:(fun g -> g 3)
+    {| (function(f){ return f.apply("this",[1,2]) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 2 cb4)
+    {| (function(f){ return f.apply("this",[1,2]) }) |};
+  [%expect {| Result: other |}]
+
+let%expect_test "wrap_meth_callback_strict" =
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 4 cb4)
+    {| (function(f){ return f.apply("this",[1,2,3]) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 4 cb4)
+    {| (function(f){ return f.apply("this",[1,2,3,4]) }) |};
+  (* Should not return a function *)
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}];
+  call_and_log
+    (Js.Unsafe.meth_callback_with_arity 4 cb4)
+    {| (function(f){ return f.apply("this",[1,2]) }) |};
+  [%expect {|
+    got this, 1, 2, undefined, done
+    Result: 0 |}]
+
+(* Wrap meth callback unsafe *)
+let%expect_test "over application, extra arguments are dropped" =
+  call_and_log
+    (Js.Unsafe.meth_callback cb4)
+    {| (function(f){ return f.apply("this",[1,2,3,4]) }) |};
+  [%expect {|
+    got this, 1, 2, 3, done
+    Result: 0 |}]
+
+let%expect_test "partial application, extra arguments set to undefined" =
+  call_and_log
+    (Js.Unsafe.meth_callback cb4)
+    {| (function(f){ return f.apply("this",[1,2]) }) |};
+  [%expect {|
+    got this, 1, 2, undefined, done
+    Result: 0 |}]
+
+(* caml_call_gen *)
+
+let%expect_test _ =
+  call_and_log cb3 ~cont:(fun g -> g 1) {| (function(f){ return f }) |};
+  [%expect {|
+    Result: other |}]
+
+(*
+let%expect_test _ =
+  call_and_log cb3 ~cont:(fun g -> g 1 2 3 4) {| (function(f){ return f }) |};
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}]
+*)
+
+let%expect_test _ =
+  let f cb =
+    try call_and_log (cb 1) ~cont:(fun g -> g 1 2 3) {| (function(f){ return f }) |} with
+    | Invalid_argument s | Failure s -> Printf.printf "Error: %s" s
+    | _ -> Printf.printf "Error: unknown"
+  in
+  f cb5;
+  [%expect {| Result: other |}];
+  f cb4;
+  [%expect {|
+    got 1, 1, 2, 3, done
+    Result: 0 |}];
+  ()
+(* f cb3;
+   [%expect {|
+     got 1, 1, 2, done
+     Result: 0 |}]
+*)
+
+let%expect_test _ =
+  let f cb =
+    try call_and_log (cb 1 2 3) {| (function(f){ return f }) |} with
+    | Invalid_argument s | Failure s -> Printf.printf "Error: %s" s
+    | _ -> Printf.printf "Error: unknown"
+  in
+  (*
+  f (Obj.magic cb1);
+  [%expect {|
+    got 1, done
+    Result: 0 |}];
+  f (Obj.magic cb2);
+  [%expect {|
+    got 1, 2, done
+    Result: 0 |}];
+*)
+  f (Obj.magic cb3);
+  [%expect {|
+    got 1, 2, 3, done
+    Result: 0 |}];
+  f (Obj.magic cb4);
+  [%expect {|
+    Result: other |}];
+  f (Obj.magic cb5);
+  [%expect {|
+    Result: other |}]
+
+let%expect_test _ =
+  let open Js_of_ocaml in
+  let f = Js.wrap_callback (fun s -> print_endline (Js.to_string s)) in
+  Js.export "f" f;
+  let () =
+    Js.Unsafe.fun_call
+      (Js.Unsafe.pure_js_expr "jsoo_exports")##.f
+      [| Js.Unsafe.coerce (Js.string "hello") |]
+  in
+  ();
+  [%expect {| hello |}]
diff --git a/lib/tests/test_poly_compare.ml b/lib/tests/test_poly_compare.ml
index b9799cc8d..62c47b46b 100644
--- a/lib/tests/test_poly_compare.ml
+++ b/lib/tests/test_poly_compare.ml
@@ -25,7 +25,6 @@ let%expect_test "poly equal" =
   assert (List.mem obj1 [ obj2; obj1 ]);
   assert (not (List.mem obj1 [ obj2 ]));
   ()
-[@@expect.uncaught_exn {| (Invalid_argument "compare: abstract value") |}]
 
 let%expect_test "poly equal neg" =
   let obj1 = Js.Unsafe.obj [||] in
@@ -50,8 +49,7 @@ let%expect_test "poly compare" =
       then print_endline "preserve"
       else print_endline "not preserve"
   | _ -> assert false);
-  [%expect.unreachable]
-[@@expect.uncaught_exn {| (Invalid_argument "compare: abstract value") |}]
+  [%expect {| not preserve |}]
 
 type pack = Pack : 'a -> pack
 
@@ -65,7 +63,6 @@ let%expect_test "number comparison" =
   assert (
     Pack (Js.Unsafe.js_expr "new Number(2.1)")
     = Pack (Js.Unsafe.js_expr "new Number(2.1)"))
-[@@expect.uncaught_exn {| "Assert_failure lib/tests/test_poly_compare.ml:59:2" |}]
 
 let js_string_enabled = Js.typeof (Obj.magic "") == Js.string "string"
 
@@ -82,7 +79,6 @@ let%expect_test "string comparison" =
   assert (
     Pack (Js.Unsafe.js_expr "new String('abcd')")
     = Pack (Js.Unsafe.js_expr "new String('abcd')"))
-[@@expect.uncaught_exn {| "Assert_failure lib/tests/test_poly_compare.ml:82:2" |}]
 
 let%expect_test "symbol comparison" =
   let s1 = Pack (Js.Unsafe.js_expr "Symbol('2')") in
@@ -92,7 +88,6 @@ let%expect_test "symbol comparison" =
   assert (compare s1 s1 = 0);
   assert (compare s1 s2 = 1);
   assert (compare s2 s1 = 1)
-[@@expect.uncaught_exn {| (Invalid_argument "compare: abstract value") |}]
 
 let%expect_test "object comparison" =
   let s1 = Pack (Js.Unsafe.js_expr "{}") in
@@ -102,7 +97,6 @@ let%expect_test "object comparison" =
   assert (compare s1 s1 = 0);
   assert (compare s1 s2 = 1);
   assert (compare s2 s1 = 1)
-[@@expect.uncaught_exn {| (Invalid_argument "compare: abstract value") |}]
 
 let%expect_test "poly compare" =
   let l =
@@ -120,13 +114,36 @@ let%expect_test "poly compare" =
   let l' = List.sort (fun (_, a) (_, b) -> compare a b) l in
   List.iter (fun (i, _) -> Printf.printf "%d\n" i) l';
   print_endline "";
-  [%expect.unreachable];
+  [%expect {|
+    1
+    3
+    2
+    0
+    6
+    7
+    5
+    4 |}];
   let l' = List.sort (fun (_, a) (_, b) -> compare a b) (List.rev l) in
   let l'' = List.sort (fun (_, a) (_, b) -> compare a b) (List.rev l') in
   List.iter (fun (i, _) -> Printf.printf "%d\n" i) l';
   print_endline "";
-  [%expect.unreachable];
+  [%expect {|
+    3
+    1
+    2
+    0
+    4
+    5
+    7
+    6 |}];
   List.iter (fun (i, _) -> Printf.printf "%d\n" i) l'';
   print_endline "";
-  [%expect.unreachable]
-[@@expect.uncaught_exn {| (Invalid_argument "compare: abstract value") |}]
+  [%expect {|
+    1
+    3
+    2
+    0
+    4
+    5
+    6
+    7 |}]
diff --git a/lib/tests/test_poly_equal.ml b/lib/tests/test_poly_equal.ml
new file mode 100644
index 000000000..0f6cf095e
--- /dev/null
+++ b/lib/tests/test_poly_equal.ml
@@ -0,0 +1,66 @@
+(* Js_of_ocaml tests
+ * http://www.ocsigen.org/js_of_ocaml/
+ * Copyright (C) 2019 Hugo Heuzard
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *)
+open Js_of_ocaml
+
+let%expect_test "poly equal" =
+  let obj1 = Js.Unsafe.obj [||] in
+  let obj2 = Js.Unsafe.obj [||] in
+  assert (obj1 = obj2);
+  assert (not (obj1 = obj2));
+  ()
+[@@expect.uncaught_exn {| "Assert_failure lib/tests/test_poly_equal.ml:24:2" |}]
+
+let%expect_test "poly equal neg" =
+  let obj1 = Js.Unsafe.obj [||] in
+  let obj2 = Js.Unsafe.obj [||] in
+  assert (obj1 <> obj2);
+  assert (not (obj1 <> obj1));
+  ()
+
+type pack = Pack : 'a -> pack
+
+let%expect_test "number comparison" =
+  assert (Pack 2 = Pack 2);
+  assert (Pack 2 <> Pack 2.1);
+  assert (Pack (Js.float 2.1) = Pack (Js.float 2.1));
+  assert (Pack (Js.Unsafe.js_expr "Number(2.1)") <> Pack 2.);
+  assert (Pack (Js.Unsafe.js_expr "new Number(2.1)") <> Pack 2.);
+  assert (Pack (Js.Unsafe.js_expr "Number(2.1)") = Pack (Js.Unsafe.js_expr "Number(2.1)"))
+
+let%expect_test "string comparison" =
+  assert (Pack (Js.Unsafe.js_expr "String(2)") = Pack (Js.string "2"));
+  assert (Pack (Js.Unsafe.js_expr "String('abc')") = Pack (Js.string "abc"));
+  assert (Pack (Js.Unsafe.js_expr "new String('abcሴ')") = Pack (Js.string "abcሴ"));
+  assert (Pack (Js.Unsafe.js_expr "String(1)") <> Pack (Js.string "2"));
+  assert (Pack (Js.Unsafe.js_expr "String('abcd')") <> Pack (Js.string "abc"));
+  assert (Pack (Js.Unsafe.js_expr "new String('abcd')") <> Pack (Js.string "abc"));
+  assert (
+    Pack (Js.Unsafe.js_expr "String('abcd')") = Pack (Js.Unsafe.js_expr "String('abcd')"))
+
+let%expect_test "symbol comparison" =
+  let s1 = Pack (Js.Unsafe.js_expr "Symbol('2')") in
+  let s2 = Pack (Js.Unsafe.js_expr "Symbol('2')") in
+  assert (s1 <> s2);
+  assert (s1 = s1)
+
+let%expect_test "object comparison" =
+  let s1 = Pack (Js.Unsafe.js_expr "{}") in
+  let s2 = Pack (Js.Unsafe.js_expr "{}") in
+  assert (s1 <> s2);
+  assert (s1 = s1)