Make actor.Stop respect the given exit reason

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## Unreleased
+
+- Fixed a bug where using `actor.Stop()` with other reasons than `Normal`
+  would stop the process with `Normal`.
+
 ## v0.16.1 - 2025-01-20
 
 - Fixed a bug where the static supervisor would return the incorrect value if

src/gleam/otp/actor.gleam

@@ -139,7 +139,7 @@ import gleam/dynamic.{type Dynamic}
 import gleam/erlang/atom
 import gleam/erlang/charlist.{type Charlist}
 import gleam/erlang/process.{
-  type ExitReason, type Pid, type Selector, type Subject, Abnormal,
+  type ExitReason, type Pid, type Selector, type Subject, Abnormal, Killed,
 }
 import gleam/option.{type Option, None, Some}
 import gleam/otp/system.{
@@ -189,7 +189,7 @@ pub fn with_selector(
 ) -> Next(message, state) {
   case value {
     Continue(state, _) -> Continue(state, Some(selector))
-    _ -> value
+    Stop(_) -> value
   }
 }
 
@@ -257,7 +257,12 @@ pub type Spec(state, msg) {
 
 // TODO: Check needed functionality here to be OTP compatible
 fn exit_process(reason: ExitReason) -> ExitReason {
-  // TODO
+  case reason {
+    Abnormal(reason) -> process.send_abnormal_exit(process.self(), reason)
+    Killed -> process.kill(process.self())
+    _ -> Nil
+  }
+
   reason
 }
 
@@ -404,10 +409,10 @@ fn initialise_actor(
       loop(self)
     }
 
-    // The init failed. Exit with an error.
+    // The init failed. Send the reason back to the parent, but exit normally.
     Failed(reason) -> {
       process.send(ack, Error(Abnormal(reason)))
-      exit_process(Abnormal(reason))
+      exit_process(process.Normal)
     }
   }
 }

test/gleam/otp/actor_test.gleam

@@ -231,6 +231,54 @@ pub fn replace_selector_test() {
   |> should.equal(dynamic.from("unknown message: String"))
 }
 
+pub fn abnormal_exit_can_be_trapped_test() {
+  process.trap_exits(True)
+  let exits =
+    process.new_selector()
+    |> process.selecting_trapped_exits(function.identity)
+
+  // Make an actor exit with an abnormal reason
+  let assert Ok(subject) =
+    actor.start(Nil, fn(_, _) { actor.Stop(process.Abnormal("reason")) })
+  process.send(subject, Nil)
+
+  let trapped_reason = process.select(exits, 10)
+
+  // Stop trapping exits, as otherwise other tests fail
+  process.trap_exits(False)
+
+  // The weird reason below is because of https://github.com/gleam-lang/erlang/issues/66
+  trapped_reason
+  |> should.equal(
+    Ok(process.ExitMessage(
+      process.subject_owner(subject),
+      process.Abnormal("Abnormal(\"reason\")"),
+    )),
+  )
+}
+
+pub fn killed_exit_can_be_trapped_test() {
+  process.trap_exits(True)
+  let exits =
+    process.new_selector()
+    |> process.selecting_trapped_exits(function.identity)
+
+  // Make an actor exit with a killed reason
+  let assert Ok(subject) =
+    actor.start(Nil, fn(_, _) { actor.Stop(process.Killed) })
+  process.send(subject, Nil)
+
+  let trapped_reason = process.select(exits, 10)
+
+  // Stop trapping exits, as otherwise other tests fail
+  process.trap_exits(False)
+
+  trapped_reason
+  |> should.equal(
+    Ok(process.ExitMessage(process.subject_owner(subject), process.Killed)),
+  )
+}
+
 fn mapped_selector(mapper: fn(a) -> ActorMessage) {
   let subject = process.new_subject()