Promises

1 files changed, 20 insertions, 0 deletions

diff --git a/test/gleam/javascript/promise_test.gleam b/test/gleam/javascript/promise_test.gleam
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+++ b/test/gleam/javascript/promise_test.gleam
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+import gleam/javascript/promise.{Promise}
+import gleam/javascript.{ObjectType}
+
+pub fn map_does_not_collapse_nested_promise_test() -> Promise(Promise(Int)) {
+  promise.resolve(1)
+  |> promise.map(promise.resolve)
+  |> promise.map(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`.
+    assert ObjectType = javascript.type_of(value)
+    value
+  })
+}
+
+pub fn then_does_collapse_nested_promise_test() -> Promise(Int) {
+  promise.resolve(1)
+  |> promise.then(promise.resolve)
+  |> promise.map(fn(value) { assert 1 = value })
+}