Add get_info to Stream

Signed-off-by: Tomasz Pietrek <tomasz@nats.io>

async-nats/src/jetstream/stream.rs

@@ -118,6 +118,8 @@ impl Display for DeleteMessageErrorKind {
 pub type DeleteMessageError = Error<DeleteMessageErrorKind>;
 
 /// Handle to operations that can be performed on a `Stream`.
+/// It's generic over the type of `info` field to allow `Stream` with or without
+/// info contents.
 #[derive(Debug, Clone)]
 pub struct Stream<T = Info> {
     pub(crate) info: T,
@@ -179,6 +181,17 @@ impl Stream<Info> {
 }
 
 impl<I> Stream<I> {
+    /// Retrieves `info` about [Stream] from the server. As this variant of [Stream] does not
+    /// contain or stores `Info`, it is returned directly.
+    pub async fn get_info(&self) -> Result<Info, InfoError> {
+        let subject = format!("STREAM.INFO.{}", self.name);
+
+        match self.context.request(subject, &json!({})).await? {
+            Response::Ok::<Info>(info) => Ok(info),
+            Response::Err { error } => Err(error.into()),
+        }
+    }
+
     /// Gets next message for a [Stream].
     ///
     /// Requires a [Stream] with `allow_direct` set to `true`.
@@ -1234,7 +1247,7 @@ pub enum StorageType {
 }
 
 /// Shows config and current state for this stream.
-#[derive(Debug, Deserialize, Clone)]
+#[derive(Debug, Deserialize, Clone, PartialEq, Eq)]
 pub struct Info {
     /// The configuration associated with this stream.
     pub config: Config,
@@ -1259,7 +1272,7 @@ pub struct DeleteStatus {
 }
 
 /// information about the given stream.
-#[derive(Debug, Deserialize, Clone, Copy)]
+#[derive(Debug, Deserialize, Clone, Copy, PartialEq, Eq)]
 pub struct State {
     /// The number of messages contained in this stream
     pub messages: u64,
@@ -1454,7 +1467,7 @@ pub struct PeerInfo {
     pub lag: Option<u64>,
 }
 
-#[derive(Debug, Clone, Deserialize)]
+#[derive(Debug, Clone, Deserialize, PartialEq, Eq)]
 pub struct SourceInfo {
     /// Source name.
     pub name: String,

async-nats/tests/jetstream_tests.rs

@@ -2303,6 +2303,38 @@ mod jetstream {
         assert!(messages.next().await.is_none());
     }
 
+    #[tokio::test]
+    async fn stream_info() {
+        let server = nats_server::run_server("tests/configs/jetstream.conf");
+        let client = ConnectOptions::new()
+            .event_callback(|err| async move { println!("error: {err:?}") })
+            .connect(server.client_url())
+            .await
+            .unwrap();
+
+        let context = async_nats::jetstream::new(client);
+
+        context
+            .create_stream(stream::Config {
+                name: "events".into(),
+                subjects: vec!["events".into()],
+                ..Default::default()
+            })
+            .await
+            .unwrap();
+
+        let mut stream = context.get_stream("events").await.unwrap();
+        assert_eq!(
+            stream.info().await.unwrap().clone(),
+            stream.cached_info().clone()
+        );
+
+        assert_eq!(
+            stream.get_info().await.unwrap().clone(),
+            stream.cached_info().clone()
+        );
+    }
+
     #[tokio::test]
     async fn consumer_info() {
         let server = nats_server::run_server("tests/configs/jetstream.conf");