1 files changed, 20 insertions, 3 deletions
diff --git a/test/gleam/javascript/promise_test.gleam b/test/gleam/javascript/promise_test.gleam
index 876aefb..289714b 100644
--- a/test/gleam/javascript/promise_test.gleam
+++ b/test/gleam/javascript/promise_test.gleam
@@ -4,17 +4,34 @@ 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) {
+  |> 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`.
     assert ObjectType = javascript.type_of(value)
-    value
   })
 }
 
+pub fn then_test() -> Promise(Int) {
+  promise.resolve(1)
+  |> promise.then(fn(a) { promise.resolve(a + 1) })
+  |> promise.tap(fn(a) { assert 2 = a })
+}
+
 pub fn then_does_collapse_nested_promise_test() -> Promise(Int) {
   promise.resolve(1)
   |> promise.then(promise.resolve)
-  |> promise.map(fn(value) { assert 1 = value })
+  |> promise.tap(fn(value) { assert 1 = value })
+}
+
+pub fn map_test() -> Promise(Int) {
+  promise.resolve(1)
+  |> promise.map(fn(a) { a + 1 })
+  |> promise.tap(fn(a) { assert 2 = a })
+}
+
+pub fn tap_test() -> Promise(Int) {
+  promise.resolve(1)
+  |> promise.tap(fn(a) { a + 1 })
+  |> promise.tap(fn(a) { assert 1 = a })
 }