Add a test for port ownership switchover

Author: mjsir911

test/gleam/erlang/port_test.gleam

@@ -1,6 +1,9 @@
 import gleam/erlang/port
 import gleam/erlang/port/receive.{Data, ExitStatus}
-import gleam/erlang/process.{receive, port_open, port_subject}
+import gleam/erlang/process.{receive, port_open, port_connect, port_subject}
+
+@external(erlang, "gleam_erlang_test_ffi", "assert_gleam_panic")
+fn assert_panic(f: fn() -> t) -> String
 
 pub fn port_open_test() {
   let assert Ok(port) = port.open(
@@ -61,3 +64,41 @@ pub fn delay_port_test() {
   assert Ok(ExitStatus(0)) == receive(subject, 100)
   assert Error(Nil) == receive(subject, 100)
 }
+
+// mirrors name_other_switchover_test in process_test a bit
+pub fn port_switchover_test() {
+  // create a new port
+  let assert Ok(port) = port.open(
+    port.spawn_executable("/bin/bash"),
+    [port.Args(["-c", "cat"]), port.UseStdio, port.ExitStatus, port.Binary]
+  )
+
+  let subject = process.port_subject(port)
+
+  // verify we can listen on it
+  port.port_command(port, <<"wasd\n">>, [])
+  assert Ok(Data(<<"wasd\n">>)) == receive(subject, 5)
+
+  // switch the owner to some other erlang process
+  let pid = process.spawn(fn() { process.sleep(20) })
+  let newsubject = port_connect(port, pid)
+
+  // try to listen on it again
+  port.port_command(port, <<"test2\n">>, [])
+  assert assert_panic(fn() { process.receive(newsubject, 0) })
+    == "Cannot receive with a subject owned by another process"
+  // test the original subject, too
+  assert assert_panic(fn() { process.receive(subject, 0) })
+    == "Cannot receive with a subject owned by another process"
+
+  // let's switch back now
+  let newnewsubject = port_connect(port, process.self())
+  port.port_command(port, <<"test3\n">>, [])
+  assert Ok(Data(<<"test3\n">>)) == receive(subject, 5)
+  port.port_command(port, <<"test4\n">>, [])
+  assert Ok(Data(<<"test4\n">>)) == receive(newsubject, 5)
+  port.port_command(port, <<"test5\n">>, [])
+  assert Ok(Data(<<"test5\n">>)) == receive(newnewsubject, 5)
+
+  port.close(port)
+}