🧪 test(message-list): add optional ignored integration test for Gmail API

tests/gmail_message_list_integration.rs

@@ -0,0 +1,36 @@
+// Optional integration test for Gmail API interactions.
+//
+// This test is ignored by default to avoid network use in CI.
+// To run locally, ensure you have valid OAuth client credentials and set up
+// the configuration as required by `ClientConfig`.
+//
+// Example to run:
+//   cargo test --test gmail_message_list_integration -- --ignored
+
+use cull_gmail::{ClientConfig, GmailClient, MessageList, Result};
+
+#[ignore]
+#[tokio::test]
+async fn list_first_page_of_messages_smoke_test() -> Result<()> {
+    // Configure with your own credentials before running locally.
+    let config = ClientConfig::builder()
+        // .with_config_base(&cull_gmail::client_config::config_root::RootBase::Home)
+        // .with_config_path(".cull-gmail")
+        // .with_credential_file("client_secret.json")
+        // Alternatively specify client_id/client_secret and related fields:
+        // .with_client_id("<your-client-id>")
+        // .with_client_secret("<your-client-secret>")
+        .build();
+
+    let mut client = GmailClient::new_with_config(config).await?;
+
+    // Configure a conservative query to avoid heavy traffic
+    client.set_query("in:inbox newer_than:30d");
+    client.set_max_results(10);
+
+    // Should complete without error; results may be empty depending on mailbox
+    client.get_messages(1).await?;
+    let _ids = client.message_ids();
+
+    Ok(())
+}