add tests

2 files changed, 18 insertions, 1 deletions

diff --git a/src/ffi.mjs b/src/ffi.mjs
index 3889aa8..4d76d2d 100644
--- a/src/ffi.mjs
+++ b/src/ffi.mjs
@@ -82,7 +82,7 @@ class PromiseLayer {
 }
 
 export function newPromise(executor) {
-  return Promise.resolve((resolve) =>
+  return new Promise((resolve) =>
     executor((value) => {
       resolve(PromiseLayer.wrap(value));
     })
diff --git a/test/gleam/javascript/promise_test.gleam b/test/gleam/javascript/promise_test.gleam
index 159b064..4699a03 100644
--- a/test/gleam/javascript/promise_test.gleam
+++ b/test/gleam/javascript/promise_test.gleam
@@ -2,6 +2,23 @@ import gleam/javascript/promise.{Promise}
 import gleam/javascript/array
 import gleam/javascript.{ObjectType}
 
+pub fn new_promise_test() {
+  promise.new(fn(resolve) { resolve(1) })
+  |> promise.tap(fn(value) {
+    let assert 1 = value
+  })
+}
+
+pub fn new_does_not_collapse_nested_promise_test() {
+  promise.new(fn(resolve) { resolve(promise.new(fn(resolve) { resolve(1) })) })
+  |> promise.tap(fn(value) {
+    // If the `Promise(Promise(Int))` collapsed into `Promise(Int)` (as they
+    // do for normal JS promises) then this would fail as the value would be the
+    // int value `1`.
+    let assert ObjectType = javascript.type_of(value)
+  })
+}
+
 pub fn map_does_not_collapse_nested_promise_test() -> Promise(Promise(Int)) {
   promise.resolve(1)
   |> promise.map(promise.resolve)