crates/nuncio-mail/Cargo.toml

@@ -9,6 +9,11 @@ repository.workspace = true
 [lints]
 workspace = true
 
+[features]
+# Exposes `test_server`, a stateful loopback IMAP server, to dependent crates'
+# test suites. Never enabled in a production build.
+test-support = []
+
 [dependencies]
 nuncio-core = { path = "../nuncio-core" }
 tokio.workspace = true

crates/nuncio-mail/src/lib.rs

@@ -10,6 +10,12 @@ pub mod mock;
 pub mod parser;
 pub mod smtp;
 
+// A real loopback IMAP server for offline tests. Behind a feature so it never
+// enters a production build, but visible to this crate's own tests and to
+// dependents that opt in (integration suites in `nunciod`).
+#[cfg(any(test, feature = "test-support"))]
+pub mod test_server;
+
 pub use backend::{
     MailBackend, MessageSender, OutboundMessage, RemoteMutationKind, RemoteMutationSpec,
 };