Add a baseline test for resume initial messages (#5466)

codex-rs/core/tests/suite/mod.rs

@@ -20,6 +20,7 @@ mod model_tools;
 mod otel;
 mod prompt_caching;
 mod read_file;
+mod resume;
 mod review;
 mod rmcp_client;
 mod rollout_list_find;

codex-rs/core/tests/suite/resume.rs

@@ -0,0 +1,64 @@
+use anyhow::Result;
+use codex_core::protocol::EventMsg;
+use codex_core::protocol::Op;
+use codex_protocol::user_input::UserInput;
+use core_test_support::responses::ev_assistant_message;
+use core_test_support::responses::ev_completed;
+use core_test_support::responses::ev_response_created;
+use core_test_support::responses::mount_sse_once_match;
+use core_test_support::responses::sse;
+use core_test_support::responses::start_mock_server;
+use core_test_support::skip_if_no_network;
+use core_test_support::test_codex::test_codex;
+use core_test_support::wait_for_event;
+use std::sync::Arc;
+use wiremock::matchers::any;
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn resume_includes_initial_messages_from_rollout_events() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let server = start_mock_server().await;
+    let mut builder = test_codex();
+    let initial = builder.build(&server).await?;
+    let codex = Arc::clone(&initial.codex);
+    let home = initial.home.clone();
+    let rollout_path = initial.session_configured.rollout_path.clone();
+
+    let initial_sse = sse(vec![
+        ev_response_created("resp-initial"),
+        ev_assistant_message("msg-1", "Completed first turn"),
+        ev_completed("resp-initial"),
+    ]);
+    mount_sse_once_match(&server, any(), initial_sse).await;
+
+    codex
+        .submit(Op::UserInput {
+            items: vec![UserInput::Text {
+                text: "Record some messages".into(),
+            }],
+        })
+        .await?;
+
+    wait_for_event(&codex, |event| matches!(event, EventMsg::TaskComplete(_))).await;
+
+    let resumed = builder.resume(&server, home, rollout_path).await?;
+    let initial_messages = resumed
+        .session_configured
+        .initial_messages
+        .expect("expected initial messages to be present for resumed session");
+    match initial_messages.as_slice() {
+        [
+            EventMsg::UserMessage(first_user),
+            EventMsg::TokenCount(_),
+            EventMsg::AgentMessage(assistant_message),
+            EventMsg::TokenCount(_),
+        ] => {
+            assert_eq!(first_user.message, "Record some messages");
+            assert_eq!(assistant_message.message, "Completed first turn");
+        }
+        other => panic!("unexpected initial messages after resume: {other:#?}"),
+    }
+
+    Ok(())
+}