diff --git a/tests/all/main.rs b/tests/all/main.rs
index 69c894435..ea2f150bd 100644
--- a/tests/all/main.rs
+++ b/tests/all/main.rs
@@ -18,7 +18,6 @@ mod math;
 mod node;
 mod non_debug;
 mod non_wasm;
-mod optional_numbers;
 mod simple;
 mod slice;
 mod structural;
diff --git a/tests/all/optional_numbers.rs b/tests/all/optional_numbers.rs
deleted file mode 100644
index 360eae050..000000000
--- a/tests/all/optional_numbers.rs
+++ /dev/null
@@ -1,331 +0,0 @@
-use super::project;
-
-#[test]
-fn works() {
-    project()
-        .requires_bigint()
-        .file(
-            "src/lib.rs",
-            r#"
-            #![feature(use_extern_macros)]
-
-            extern crate wasm_bindgen;
-
-            use wasm_bindgen::prelude::*;
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn i32_js_identity(a: Option<i32>) -> Option<i32>;
-            }
-            #[wasm_bindgen]
-            pub fn i32_none() -> Option<i32> { None }
-            #[wasm_bindgen]
-            pub fn i32_zero() -> Option<i32> { Some(0) }
-            #[wasm_bindgen]
-            pub fn i32_one() -> Option<i32> { Some(1) }
-            #[wasm_bindgen]
-            pub fn i32_neg_one() -> Option<i32> { Some(-1) }
-            #[wasm_bindgen]
-            pub fn i32_max() -> Option<i32> { Some(i32::max_value()) }
-            #[wasm_bindgen]
-            pub fn i32_min() -> Option<i32> { Some(i32::min_value()) }
-            #[wasm_bindgen]
-            pub fn i32_identity(a: Option<i32>) -> Option<i32> { i32_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn u32_js_identity(a: Option<u32>) -> Option<u32>;
-            }
-            #[wasm_bindgen]
-            pub fn u32_none() -> Option<u32> { None }
-            #[wasm_bindgen]
-            pub fn u32_zero() -> Option<u32> { Some(0) }
-            #[wasm_bindgen]
-            pub fn u32_one() -> Option<u32> { Some(1) }
-            #[wasm_bindgen]
-            pub fn u32_max() -> Option<u32> { Some(u32::max_value()) }
-            #[wasm_bindgen]
-            pub fn u32_min() -> Option<u32> { Some(u32::min_value()) }
-            #[wasm_bindgen]
-            pub fn u32_identity(a: Option<u32>) -> Option<u32> { u32_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn isize_js_identity(a: Option<isize>) -> Option<isize>;
-            }
-            #[wasm_bindgen]
-            pub fn isize_none() -> Option<isize> { None }
-            #[wasm_bindgen]
-            pub fn isize_zero() -> Option<isize> { Some(0) }
-            #[wasm_bindgen]
-            pub fn isize_one() -> Option<isize> { Some(1) }
-            #[wasm_bindgen]
-            pub fn isize_neg_one() -> Option<isize> { Some(-1) }
-            #[wasm_bindgen]
-            pub fn isize_max() -> Option<isize> { Some(isize::max_value()) }
-            #[wasm_bindgen]
-            pub fn isize_min() -> Option<isize> { Some(isize::min_value()) }
-            #[wasm_bindgen]
-            pub fn isize_identity(a: Option<isize>) -> Option<isize> { isize_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn usize_js_identity(a: Option<usize>) -> Option<usize>;
-            }
-            #[wasm_bindgen]
-            pub fn usize_none() -> Option<usize> { None }
-            #[wasm_bindgen]
-            pub fn usize_zero() -> Option<usize> { Some(0) }
-            #[wasm_bindgen]
-            pub fn usize_one() -> Option<usize> { Some(1) }
-            #[wasm_bindgen]
-            pub fn usize_max() -> Option<usize> { Some(usize::max_value()) }
-            #[wasm_bindgen]
-            pub fn usize_min() -> Option<usize> { Some(usize::min_value()) }
-            #[wasm_bindgen]
-            pub fn usize_identity(a: Option<usize>) -> Option<usize> { usize_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn f32_js_identity(a: Option<f32>) -> Option<f32>;
-            }
-            #[wasm_bindgen]
-            pub fn f32_none() -> Option<f32> { None }
-            #[wasm_bindgen]
-            pub fn f32_zero() -> Option<f32> { Some(0f32) }
-            #[wasm_bindgen]
-            pub fn f32_one() -> Option<f32> { Some(1f32) }
-            #[wasm_bindgen]
-            pub fn f32_neg_one() -> Option<f32> { Some(-1f32) }
-            #[wasm_bindgen]
-            pub fn f32_identity(a: Option<f32>) -> Option<f32> { f32_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn f64_js_identity(a: Option<f64>) -> Option<f64>;
-            }
-            #[wasm_bindgen]
-            pub fn f64_none() -> Option<f64> { None }
-            #[wasm_bindgen]
-            pub fn f64_zero() -> Option<f64> { Some(0f64) }
-            #[wasm_bindgen]
-            pub fn f64_one() -> Option<f64> { Some(1f64) }
-            #[wasm_bindgen]
-            pub fn f64_neg_one() -> Option<f64> { Some(-1f64) }
-            #[wasm_bindgen]
-            pub fn f64_identity(a: Option<f64>) -> Option<f64> { f64_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn i8_js_identity(a: Option<i8>) -> Option<i8>;
-            }
-            #[wasm_bindgen]
-            pub fn i8_none() -> Option<i8> { None }
-            #[wasm_bindgen]
-            pub fn i8_zero() -> Option<i8> { Some(0) }
-            #[wasm_bindgen]
-            pub fn i8_one() -> Option<i8> { Some(1) }
-            #[wasm_bindgen]
-            pub fn i8_neg_one() -> Option<i8> { Some(-1) }
-            #[wasm_bindgen]
-            pub fn i8_max() -> Option<i8> { Some(i8::max_value()) }
-            #[wasm_bindgen]
-            pub fn i8_min() -> Option<i8> { Some(i8::min_value()) }
-            #[wasm_bindgen]
-            pub fn i8_identity(a: Option<i8>) -> Option<i8> { i8_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn u8_js_identity(a: Option<u8>) -> Option<u8>;
-            }
-            #[wasm_bindgen]
-            pub fn u8_none() -> Option<u8> { None }
-            #[wasm_bindgen]
-            pub fn u8_zero() -> Option<u8> { Some(0) }
-            #[wasm_bindgen]
-            pub fn u8_one() -> Option<u8> { Some(1) }
-            #[wasm_bindgen]
-            pub fn u8_max() -> Option<u8> { Some(u8::max_value()) }
-            #[wasm_bindgen]
-            pub fn u8_min() -> Option<u8> { Some(u8::min_value()) }
-            #[wasm_bindgen]
-            pub fn u8_identity(a: Option<u8>) -> Option<u8> { u8_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn i16_js_identity(a: Option<i16>) -> Option<i16>;
-            }
-            #[wasm_bindgen]
-            pub fn i16_none() -> Option<i16> { None }
-            #[wasm_bindgen]
-            pub fn i16_zero() -> Option<i16> { Some(0) }
-            #[wasm_bindgen]
-            pub fn i16_one() -> Option<i16> { Some(1) }
-            #[wasm_bindgen]
-            pub fn i16_neg_one() -> Option<i16> { Some(-1) }
-            #[wasm_bindgen]
-            pub fn i16_max() -> Option<i16> { Some(i16::max_value()) }
-            #[wasm_bindgen]
-            pub fn i16_min() -> Option<i16> { Some(i16::min_value()) }
-            #[wasm_bindgen]
-            pub fn i16_identity(a: Option<i16>) -> Option<i16> { i16_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn u16_js_identity(a: Option<u16>) -> Option<u16>;
-            }
-            #[wasm_bindgen]
-            pub fn u16_none() -> Option<u16> { None }
-            #[wasm_bindgen]
-            pub fn u16_zero() -> Option<u16> { Some(0) }
-            #[wasm_bindgen]
-            pub fn u16_one() -> Option<u16> { Some(1) }
-            #[wasm_bindgen]
-            pub fn u16_max() -> Option<u16> { Some(u16::max_value()) }
-            #[wasm_bindgen]
-            pub fn u16_min() -> Option<u16> { Some(u16::min_value()) }
-            #[wasm_bindgen]
-            pub fn u16_identity(a: Option<u16>) -> Option<u16> { u16_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn i64_js_identity(a: Option<i64>) -> Option<i64>;
-            }
-            #[wasm_bindgen]
-            pub fn i64_none() -> Option<i64> { None }
-            #[wasm_bindgen]
-            pub fn i64_zero() -> Option<i64> { Some(0) }
-            #[wasm_bindgen]
-            pub fn i64_one() -> Option<i64> { Some(1) }
-            #[wasm_bindgen]
-            pub fn i64_neg_one() -> Option<i64> { Some(-1) }
-            #[wasm_bindgen]
-            pub fn i64_max() -> Option<i64> { Some(i64::max_value()) }
-            #[wasm_bindgen]
-            pub fn i64_min() -> Option<i64> { Some(i64::min_value()) }
-            #[wasm_bindgen]
-            pub fn i64_identity(a: Option<i64>) -> Option<i64> { i64_js_identity(a) }
-
-            #[wasm_bindgen(module = "./test")]
-            extern {
-                fn u64_js_identity(a: Option<u64>) -> Option<u64>;
-            }
-            #[wasm_bindgen]
-            pub fn u64_none() -> Option<u64> { None }
-            #[wasm_bindgen]
-            pub fn u64_zero() -> Option<u64> { Some(0) }
-            #[wasm_bindgen]
-            pub fn u64_one() -> Option<u64> { Some(1) }
-            #[wasm_bindgen]
-            pub fn u64_max() -> Option<u64> { Some(u64::max_value()) }
-            #[wasm_bindgen]
-            pub fn u64_min() -> Option<u64> { Some(u64::min_value()) }
-            #[wasm_bindgen]
-            pub fn u64_identity(a: Option<u64>) -> Option<u64> { u64_js_identity(a) }
-        "#,
-        )
-        .file(
-            "test.js",
-            r#"
-            import * as wasm from './out';
-
-            function assertEq(a, b) {
-              console.log(a, '?=', b);
-              if (a === b)
-                return;
-              throw new Error('not equal');
-            }
-
-            export function test() {
-              assertEq(wasm.i32_identity(wasm.i32_none()), undefined);
-              assertEq(wasm.i32_identity(wasm.i32_zero()), 0);
-              assertEq(wasm.i32_identity(wasm.i32_one()), 1);
-              assertEq(wasm.i32_identity(wasm.i32_neg_one()), -1);
-              assertEq(wasm.i32_identity(wasm.i32_max()), 2147483647);
-              assertEq(wasm.i32_identity(wasm.i32_min()), -2147483648);
-
-              assertEq(wasm.u32_identity(wasm.u32_none()), undefined);
-              assertEq(wasm.u32_identity(wasm.u32_zero()), 0);
-              assertEq(wasm.u32_identity(wasm.u32_one()), 1);
-              assertEq(wasm.u32_identity(wasm.u32_max()), 4294967295);
-              assertEq(wasm.u32_identity(wasm.u32_min()), 0);
-
-              assertEq(wasm.isize_identity(wasm.isize_none()), undefined);
-              assertEq(wasm.isize_identity(wasm.isize_zero()), 0);
-              assertEq(wasm.isize_identity(wasm.isize_one()), 1);
-              assertEq(wasm.isize_identity(wasm.isize_neg_one()), -1);
-              assertEq(wasm.isize_identity(wasm.isize_max()), 2147483647);
-              assertEq(wasm.isize_identity(wasm.isize_min()), -2147483648);
-
-              assertEq(wasm.usize_identity(wasm.usize_none()), undefined);
-              assertEq(wasm.usize_identity(wasm.usize_zero()), 0);
-              assertEq(wasm.usize_identity(wasm.usize_one()), 1);
-              assertEq(wasm.usize_identity(wasm.usize_max()), 4294967295);
-              assertEq(wasm.usize_identity(wasm.usize_min()), 0);
-
-              assertEq(wasm.f32_identity(wasm.f32_none()), undefined);
-              assertEq(wasm.f32_identity(wasm.f32_zero()), 0);
-              assertEq(wasm.f32_identity(wasm.f32_one()), 1);
-              assertEq(wasm.f32_identity(wasm.f32_neg_one()), -1);
-
-              assertEq(wasm.f64_identity(wasm.f64_none()), undefined);
-              assertEq(wasm.f64_identity(wasm.f64_zero()), 0);
-              assertEq(wasm.f64_identity(wasm.f64_one()), 1);
-              assertEq(wasm.f64_identity(wasm.f64_neg_one()), -1);
-
-              assertEq(wasm.i8_identity(wasm.i8_none()), undefined);
-              assertEq(wasm.i8_identity(wasm.i8_zero()), 0);
-              assertEq(wasm.i8_identity(wasm.i8_one()), 1);
-              assertEq(wasm.i8_identity(wasm.i8_neg_one()), -1);
-              assertEq(wasm.i8_identity(wasm.i8_max()), 127);
-              assertEq(wasm.i8_identity(wasm.i8_min()), -128);
-
-              assertEq(wasm.u8_identity(wasm.u8_none()), undefined);
-              assertEq(wasm.u8_identity(wasm.u8_zero()), 0);
-              assertEq(wasm.u8_identity(wasm.u8_one()), 1);
-              assertEq(wasm.u8_identity(wasm.u8_max()), 255);
-              assertEq(wasm.u8_identity(wasm.u8_min()), 0);
-
-              assertEq(wasm.i16_identity(wasm.i16_none()), undefined);
-              assertEq(wasm.i16_identity(wasm.i16_zero()), 0);
-              assertEq(wasm.i16_identity(wasm.i16_one()), 1);
-              assertEq(wasm.i16_identity(wasm.i16_neg_one()), -1);
-              assertEq(wasm.i16_identity(wasm.i16_max()), 32767);
-              assertEq(wasm.i16_identity(wasm.i16_min()), -32768);
-
-              assertEq(wasm.u16_identity(wasm.u16_none()), undefined);
-              assertEq(wasm.u16_identity(wasm.u16_zero()), 0);
-              assertEq(wasm.u16_identity(wasm.u16_one()), 1);
-              assertEq(wasm.u16_identity(wasm.u16_max()), 65535);
-              assertEq(wasm.u16_identity(wasm.u16_min()), 0);
-
-              assertEq(wasm.i64_identity(wasm.i64_none()), undefined);
-              assertEq(wasm.i64_identity(wasm.i64_zero()), BigInt("0"));
-              assertEq(wasm.i64_identity(wasm.i64_one()), BigInt("1"));
-              assertEq(wasm.i64_identity(wasm.i64_neg_one()), BigInt("-1"));
-              assertEq(wasm.i64_identity(wasm.i64_max()), BigInt("9223372036854775807"));
-              assertEq(wasm.i64_identity(wasm.i64_min()), BigInt("-9223372036854775808"));
-
-              assertEq(wasm.u64_identity(wasm.u64_none()), undefined);
-              assertEq(wasm.u64_identity(wasm.u64_zero()), BigInt("0"));
-              assertEq(wasm.u64_identity(wasm.u64_one()), BigInt("1"));
-              assertEq(wasm.u64_identity(wasm.u64_max()), BigInt("18446744073709551615"));
-              assertEq(wasm.u64_identity(wasm.u64_min()), BigInt("0"));
-            }
-
-            export function i32_js_identity(a) { return a; }
-            export function u32_js_identity(a) { return a; }
-            export function isize_js_identity(a) { return a; }
-            export function usize_js_identity(a) { return a; }
-            export function f32_js_identity(a) { return a; }
-            export function f64_js_identity(a) { return a; }
-            export function i8_js_identity(a) { return a; }
-            export function u8_js_identity(a) { return a; }
-            export function i16_js_identity(a) { return a; }
-            export function u16_js_identity(a) { return a; }
-            export function i64_js_identity(a) { return a; }
-            export function u64_js_identity(a) { return a; }
-        "#,
-        )
-        .test();
-}
diff --git a/tests/wasm/main.rs b/tests/wasm/main.rs
index ea4252af2..453983037 100644
--- a/tests/wasm/main.rs
+++ b/tests/wasm/main.rs
@@ -6,3 +6,4 @@ extern crate wasm_bindgen;
 
 pub mod api;
 pub mod option;
+pub mod optional_numbers;
diff --git a/tests/wasm/optional_numbers.js b/tests/wasm/optional_numbers.js
new file mode 100644
index 000000000..55e600f5f
--- /dev/null
+++ b/tests/wasm/optional_numbers.js
@@ -0,0 +1,92 @@
+const assert = require('assert');
+const wasm = require('wasm-bindgen-test.js');
+
+exports.test_works = function() {
+  assert.strictEqual(wasm.i32_identity(wasm.i32_none()), undefined);
+  assert.strictEqual(wasm.i32_identity(wasm.i32_zero()), 0);
+  assert.strictEqual(wasm.i32_identity(wasm.i32_one()), 1);
+  assert.strictEqual(wasm.i32_identity(wasm.i32_neg_one()), -1);
+  assert.strictEqual(wasm.i32_identity(wasm.i32_max()), 2147483647);
+  assert.strictEqual(wasm.i32_identity(wasm.i32_min()), -2147483648);
+
+  assert.strictEqual(wasm.u32_identity(wasm.u32_none()), undefined);
+  assert.strictEqual(wasm.u32_identity(wasm.u32_zero()), 0);
+  assert.strictEqual(wasm.u32_identity(wasm.u32_one()), 1);
+  assert.strictEqual(wasm.u32_identity(wasm.u32_max()), 4294967295);
+  assert.strictEqual(wasm.u32_identity(wasm.u32_min()), 0);
+
+  assert.strictEqual(wasm.isize_identity(wasm.isize_none()), undefined);
+  assert.strictEqual(wasm.isize_identity(wasm.isize_zero()), 0);
+  assert.strictEqual(wasm.isize_identity(wasm.isize_one()), 1);
+  assert.strictEqual(wasm.isize_identity(wasm.isize_neg_one()), -1);
+  assert.strictEqual(wasm.isize_identity(wasm.isize_max()), 2147483647);
+  assert.strictEqual(wasm.isize_identity(wasm.isize_min()), -2147483648);
+
+  assert.strictEqual(wasm.usize_identity(wasm.usize_none()), undefined);
+  assert.strictEqual(wasm.usize_identity(wasm.usize_zero()), 0);
+  assert.strictEqual(wasm.usize_identity(wasm.usize_one()), 1);
+  assert.strictEqual(wasm.usize_identity(wasm.usize_max()), 4294967295);
+  assert.strictEqual(wasm.usize_identity(wasm.usize_min()), 0);
+
+  assert.strictEqual(wasm.f32_identity(wasm.f32_none()), undefined);
+  assert.strictEqual(wasm.f32_identity(wasm.f32_zero()), 0);
+  assert.strictEqual(wasm.f32_identity(wasm.f32_one()), 1);
+  assert.strictEqual(wasm.f32_identity(wasm.f32_neg_one()), -1);
+
+  assert.strictEqual(wasm.f64_identity(wasm.f64_none()), undefined);
+  assert.strictEqual(wasm.f64_identity(wasm.f64_zero()), 0);
+  assert.strictEqual(wasm.f64_identity(wasm.f64_one()), 1);
+  assert.strictEqual(wasm.f64_identity(wasm.f64_neg_one()), -1);
+
+  assert.strictEqual(wasm.i8_identity(wasm.i8_none()), undefined);
+  assert.strictEqual(wasm.i8_identity(wasm.i8_zero()), 0);
+  assert.strictEqual(wasm.i8_identity(wasm.i8_one()), 1);
+  assert.strictEqual(wasm.i8_identity(wasm.i8_neg_one()), -1);
+  assert.strictEqual(wasm.i8_identity(wasm.i8_max()), 127);
+  assert.strictEqual(wasm.i8_identity(wasm.i8_min()), -128);
+
+  assert.strictEqual(wasm.u8_identity(wasm.u8_none()), undefined);
+  assert.strictEqual(wasm.u8_identity(wasm.u8_zero()), 0);
+  assert.strictEqual(wasm.u8_identity(wasm.u8_one()), 1);
+  assert.strictEqual(wasm.u8_identity(wasm.u8_max()), 255);
+  assert.strictEqual(wasm.u8_identity(wasm.u8_min()), 0);
+
+  assert.strictEqual(wasm.i16_identity(wasm.i16_none()), undefined);
+  assert.strictEqual(wasm.i16_identity(wasm.i16_zero()), 0);
+  assert.strictEqual(wasm.i16_identity(wasm.i16_one()), 1);
+  assert.strictEqual(wasm.i16_identity(wasm.i16_neg_one()), -1);
+  assert.strictEqual(wasm.i16_identity(wasm.i16_max()), 32767);
+  assert.strictEqual(wasm.i16_identity(wasm.i16_min()), -32768);
+
+  assert.strictEqual(wasm.u16_identity(wasm.u16_none()), undefined);
+  assert.strictEqual(wasm.u16_identity(wasm.u16_zero()), 0);
+  assert.strictEqual(wasm.u16_identity(wasm.u16_one()), 1);
+  assert.strictEqual(wasm.u16_identity(wasm.u16_max()), 65535);
+  assert.strictEqual(wasm.u16_identity(wasm.u16_min()), 0);
+
+  assert.strictEqual(wasm.i64_identity(wasm.i64_none()), undefined);
+  assert.strictEqual(wasm.i64_identity(wasm.i64_zero()), BigInt("0"));
+  assert.strictEqual(wasm.i64_identity(wasm.i64_one()), BigInt("1"));
+  assert.strictEqual(wasm.i64_identity(wasm.i64_neg_one()), BigInt("-1"));
+  assert.strictEqual(wasm.i64_identity(wasm.i64_max()), BigInt("9223372036854775807"));
+  assert.strictEqual(wasm.i64_identity(wasm.i64_min()), BigInt("-9223372036854775808"));
+
+  assert.strictEqual(wasm.u64_identity(wasm.u64_none()), undefined);
+  assert.strictEqual(wasm.u64_identity(wasm.u64_zero()), BigInt("0"));
+  assert.strictEqual(wasm.u64_identity(wasm.u64_one()), BigInt("1"));
+  assert.strictEqual(wasm.u64_identity(wasm.u64_max()), BigInt("18446744073709551615"));
+  assert.strictEqual(wasm.u64_identity(wasm.u64_min()), BigInt("0"));
+};
+
+exports.i32_js_identity = function(a) { return a; }
+exports.u32_js_identity = function(a) { return a; }
+exports.isize_js_identity = function(a) { return a; }
+exports.usize_js_identity = function(a) { return a; }
+exports.f32_js_identity = function(a) { return a; }
+exports.f64_js_identity = function(a) { return a; }
+exports.i8_js_identity = function(a) { return a; }
+exports.u8_js_identity = function(a) { return a; }
+exports.i16_js_identity = function(a) { return a; }
+exports.u16_js_identity = function(a) { return a; }
+exports.i64_js_identity = function(a) { return a; }
+exports.u64_js_identity = function(a) { return a; }
diff --git a/tests/wasm/optional_numbers.rs b/tests/wasm/optional_numbers.rs
new file mode 100644
index 000000000..34f187cdf
--- /dev/null
+++ b/tests/wasm/optional_numbers.rs
@@ -0,0 +1,187 @@
+use wasm_bindgen_test::*;
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen(module = "tests/wasm/optional_numbers.js", version = "*")]
+extern {
+    fn i32_js_identity(a: Option<i32>) -> Option<i32>;
+    fn u32_js_identity(a: Option<u32>) -> Option<u32>;
+    fn isize_js_identity(a: Option<isize>) -> Option<isize>;
+    fn usize_js_identity(a: Option<usize>) -> Option<usize>;
+    fn f32_js_identity(a: Option<f32>) -> Option<f32>;
+    fn f64_js_identity(a: Option<f64>) -> Option<f64>;
+    fn i8_js_identity(a: Option<i8>) -> Option<i8>;
+    fn u8_js_identity(a: Option<u8>) -> Option<u8>;
+    fn i16_js_identity(a: Option<i16>) -> Option<i16>;
+    fn u16_js_identity(a: Option<u16>) -> Option<u16>;
+    fn i64_js_identity(a: Option<i64>) -> Option<i64>;
+    fn u64_js_identity(a: Option<u64>) -> Option<u64>;
+
+    fn test_works();
+}
+
+#[wasm_bindgen]
+pub fn i32_none() -> Option<i32> { None }
+#[wasm_bindgen]
+pub fn i32_zero() -> Option<i32> { Some(0) }
+#[wasm_bindgen]
+pub fn i32_one() -> Option<i32> { Some(1) }
+#[wasm_bindgen]
+pub fn i32_neg_one() -> Option<i32> { Some(-1) }
+#[wasm_bindgen]
+pub fn i32_max() -> Option<i32> { Some(i32::max_value()) }
+#[wasm_bindgen]
+pub fn i32_min() -> Option<i32> { Some(i32::min_value()) }
+#[wasm_bindgen]
+pub fn i32_identity(a: Option<i32>) -> Option<i32> { i32_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn u32_none() -> Option<u32> { None }
+#[wasm_bindgen]
+pub fn u32_zero() -> Option<u32> { Some(0) }
+#[wasm_bindgen]
+pub fn u32_one() -> Option<u32> { Some(1) }
+#[wasm_bindgen]
+pub fn u32_max() -> Option<u32> { Some(u32::max_value()) }
+#[wasm_bindgen]
+pub fn u32_min() -> Option<u32> { Some(u32::min_value()) }
+#[wasm_bindgen]
+pub fn u32_identity(a: Option<u32>) -> Option<u32> { u32_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn isize_none() -> Option<isize> { None }
+#[wasm_bindgen]
+pub fn isize_zero() -> Option<isize> { Some(0) }
+#[wasm_bindgen]
+pub fn isize_one() -> Option<isize> { Some(1) }
+#[wasm_bindgen]
+pub fn isize_neg_one() -> Option<isize> { Some(-1) }
+#[wasm_bindgen]
+pub fn isize_max() -> Option<isize> { Some(isize::max_value()) }
+#[wasm_bindgen]
+pub fn isize_min() -> Option<isize> { Some(isize::min_value()) }
+#[wasm_bindgen]
+pub fn isize_identity(a: Option<isize>) -> Option<isize> { isize_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn usize_none() -> Option<usize> { None }
+#[wasm_bindgen]
+pub fn usize_zero() -> Option<usize> { Some(0) }
+#[wasm_bindgen]
+pub fn usize_one() -> Option<usize> { Some(1) }
+#[wasm_bindgen]
+pub fn usize_max() -> Option<usize> { Some(usize::max_value()) }
+#[wasm_bindgen]
+pub fn usize_min() -> Option<usize> { Some(usize::min_value()) }
+#[wasm_bindgen]
+pub fn usize_identity(a: Option<usize>) -> Option<usize> { usize_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn f32_none() -> Option<f32> { None }
+#[wasm_bindgen]
+pub fn f32_zero() -> Option<f32> { Some(0f32) }
+#[wasm_bindgen]
+pub fn f32_one() -> Option<f32> { Some(1f32) }
+#[wasm_bindgen]
+pub fn f32_neg_one() -> Option<f32> { Some(-1f32) }
+#[wasm_bindgen]
+pub fn f32_identity(a: Option<f32>) -> Option<f32> { f32_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn f64_none() -> Option<f64> { None }
+#[wasm_bindgen]
+pub fn f64_zero() -> Option<f64> { Some(0f64) }
+#[wasm_bindgen]
+pub fn f64_one() -> Option<f64> { Some(1f64) }
+#[wasm_bindgen]
+pub fn f64_neg_one() -> Option<f64> { Some(-1f64) }
+#[wasm_bindgen]
+pub fn f64_identity(a: Option<f64>) -> Option<f64> { f64_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn i8_none() -> Option<i8> { None }
+#[wasm_bindgen]
+pub fn i8_zero() -> Option<i8> { Some(0) }
+#[wasm_bindgen]
+pub fn i8_one() -> Option<i8> { Some(1) }
+#[wasm_bindgen]
+pub fn i8_neg_one() -> Option<i8> { Some(-1) }
+#[wasm_bindgen]
+pub fn i8_max() -> Option<i8> { Some(i8::max_value()) }
+#[wasm_bindgen]
+pub fn i8_min() -> Option<i8> { Some(i8::min_value()) }
+#[wasm_bindgen]
+pub fn i8_identity(a: Option<i8>) -> Option<i8> { i8_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn u8_none() -> Option<u8> { None }
+#[wasm_bindgen]
+pub fn u8_zero() -> Option<u8> { Some(0) }
+#[wasm_bindgen]
+pub fn u8_one() -> Option<u8> { Some(1) }
+#[wasm_bindgen]
+pub fn u8_max() -> Option<u8> { Some(u8::max_value()) }
+#[wasm_bindgen]
+pub fn u8_min() -> Option<u8> { Some(u8::min_value()) }
+#[wasm_bindgen]
+pub fn u8_identity(a: Option<u8>) -> Option<u8> { u8_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn i16_none() -> Option<i16> { None }
+#[wasm_bindgen]
+pub fn i16_zero() -> Option<i16> { Some(0) }
+#[wasm_bindgen]
+pub fn i16_one() -> Option<i16> { Some(1) }
+#[wasm_bindgen]
+pub fn i16_neg_one() -> Option<i16> { Some(-1) }
+#[wasm_bindgen]
+pub fn i16_max() -> Option<i16> { Some(i16::max_value()) }
+#[wasm_bindgen]
+pub fn i16_min() -> Option<i16> { Some(i16::min_value()) }
+#[wasm_bindgen]
+pub fn i16_identity(a: Option<i16>) -> Option<i16> { i16_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn u16_none() -> Option<u16> { None }
+#[wasm_bindgen]
+pub fn u16_zero() -> Option<u16> { Some(0) }
+#[wasm_bindgen]
+pub fn u16_one() -> Option<u16> { Some(1) }
+#[wasm_bindgen]
+pub fn u16_max() -> Option<u16> { Some(u16::max_value()) }
+#[wasm_bindgen]
+pub fn u16_min() -> Option<u16> { Some(u16::min_value()) }
+#[wasm_bindgen]
+pub fn u16_identity(a: Option<u16>) -> Option<u16> { u16_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn i64_none() -> Option<i64> { None }
+#[wasm_bindgen]
+pub fn i64_zero() -> Option<i64> { Some(0) }
+#[wasm_bindgen]
+pub fn i64_one() -> Option<i64> { Some(1) }
+#[wasm_bindgen]
+pub fn i64_neg_one() -> Option<i64> { Some(-1) }
+#[wasm_bindgen]
+pub fn i64_max() -> Option<i64> { Some(i64::max_value()) }
+#[wasm_bindgen]
+pub fn i64_min() -> Option<i64> { Some(i64::min_value()) }
+#[wasm_bindgen]
+pub fn i64_identity(a: Option<i64>) -> Option<i64> { i64_js_identity(a) }
+
+#[wasm_bindgen]
+pub fn u64_none() -> Option<u64> { None }
+#[wasm_bindgen]
+pub fn u64_zero() -> Option<u64> { Some(0) }
+#[wasm_bindgen]
+pub fn u64_one() -> Option<u64> { Some(1) }
+#[wasm_bindgen]
+pub fn u64_max() -> Option<u64> { Some(u64::max_value()) }
+#[wasm_bindgen]
+pub fn u64_min() -> Option<u64> { Some(u64::min_value()) }
+#[wasm_bindgen]
+pub fn u64_identity(a: Option<u64>) -> Option<u64> { u64_js_identity(a) }
+
+#[wasm_bindgen_test]
+fn works() {
+    test_works();
+}