feat: remove validation on Subscribe::new_many() (#422)

Reverts #392 as the feature is deemed unnecessary.

Signed-off-by: Devdutt Shenoi <devdutt@bytebeam.io>

CHANGELOG.md

@@ -1,7 +1,8 @@
 ----------------
 rumqttc
------------
-- Change variants in `ClientError` to not expose dependence on flume/`SendError`.
+----------
+- Change variants in `ClientError` to not expose dependence on flume/`SendError` (#420)
+- Revert erroring out when Subscription filter list is empty (#422).
 
 -----------
 

rumqttc/src/client.rs

@@ -1,6 +1,6 @@
 //! This module offers a high level synchronous and asynchronous abstraction to
 //! async eventloop.
-use crate::mqttbytes::{self, v4::*, QoS};
+use crate::mqttbytes::{v4::*, QoS};
 use crate::{ConnectionError, Event, EventLoop, MqttOptions, Request};
 
 use bytes::Bytes;
@@ -18,8 +18,6 @@ pub enum ClientError {
     Request(Request),
     #[error("Failed to send mqtt requests to eventloop")]
     TryRequest(Request),
-    #[error("Serialization error: {0}")]
-    Mqtt4(#[from] mqttbytes::Error),
 }
 
 impl From<SendError<()>> for ClientError {
@@ -168,7 +166,7 @@ impl AsyncClient {
     where
         T: IntoIterator<Item = SubscribeFilter>,
     {
-        let subscribe = Subscribe::new_many(topics)?;
+        let subscribe = Subscribe::new_many(topics);
         let request = Request::Subscribe(subscribe);
         self.request_tx.send_async(request).await?;
         Ok(())
@@ -179,7 +177,7 @@ impl AsyncClient {
     where
         T: IntoIterator<Item = SubscribeFilter>,
     {
-        let subscribe = Subscribe::new_many(topics)?;
+        let subscribe = Subscribe::new_many(topics);
         let request = Request::Subscribe(subscribe);
         self.request_tx.try_send(request)?;
         Ok(())

rumqttc/src/mqttbytes/v4/subscribe.rs

@@ -21,16 +21,13 @@ impl Subscribe {
         }
     }
 
-    pub fn new_many<T>(topics: T) -> Result<Subscribe, Error>
+    pub fn new_many<T>(topics: T) -> Subscribe
     where
         T: IntoIterator<Item = SubscribeFilter>,
     {
         let filters: Vec<SubscribeFilter> = topics.into_iter().collect();
 
-        match filters.len() {
-            0 => Err(Error::EmptySubscription),
-            _ => Ok(Subscribe { pkid: 0, filters }),
-        }
+        Subscribe { pkid: 0, filters }
     }
 
     pub fn add(&mut self, path: String, qos: QoS) -> &mut Self {