diff --git a/rpc/Cargo.toml b/rpc/Cargo.toml
index 6c9e195..c93d940 100644
--- a/rpc/Cargo.toml
+++ b/rpc/Cargo.toml
@@ -33,3 +33,4 @@ futures-test-preview = { version = "0.3.0-alpha.17" }
 env_logger = "0.6"
 tokio = "0.1"
 tokio-executor = "0.1"
+assert_matches = "1.0"
diff --git a/rpc/src/server/filter.rs b/rpc/src/server/filter.rs
index 299b005..78419bf 100644
--- a/rpc/src/server/filter.rs
+++ b/rpc/src/server/filter.rs
@@ -7,7 +7,6 @@
 use crate::{
     server::{self, Channel},
     util::Compact,
-    Response,
 };
 use fnv::FnvHashMap;
 use futures::{
@@ -22,7 +21,7 @@ use log::{debug, info, trace};
 use pin_utils::{unsafe_pinned, unsafe_unpinned};
 use std::sync::{Arc, Weak};
 use std::{
-    collections::hash_map::Entry, convert::TryInto, fmt, hash::Hash, io, marker::Unpin, pin::Pin,
+    collections::hash_map::Entry, convert::TryInto, fmt, hash::Hash, marker::Unpin, pin::Pin,
 };
 
 /// A single-threaded filter that drops channels based on per-key limits.
@@ -63,34 +62,9 @@ impl<K> Drop for Tracker<K> {
     }
 }
 
-/// A running handler serving all requests for a single client.
-#[derive(Debug)]
-pub struct TrackedHandler<K, Fut> {
-    inner: Fut,
-    tracker: Tracker<K>,
-}
-
-impl<K, Fut> TrackedHandler<K, Fut>
-where
-    Fut: Future,
-{
-    unsafe_pinned!(inner: Fut);
-}
-
-impl<K, Fut> Future for TrackedHandler<K, Fut>
-where
-    Fut: Future,
-{
-    type Output = Fut::Output;
-
-    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
-        self.inner().poll(cx)
-    }
-}
-
 impl<C, K> Stream for TrackedChannel<C, K>
 where
-    C: Channel,
+    C: Stream,
 {
     type Item = <C as Stream>::Item;
 
@@ -99,17 +73,17 @@ where
     }
 }
 
-impl<C, K> Sink<Response<C::Resp>> for TrackedChannel<C, K>
+impl<C, I, K> Sink<I> for TrackedChannel<C, K>
 where
-    C: Channel,
+    C: Sink<I>,
 {
-    type Error = io::Error;
+    type Error = C::Error;
 
     fn poll_ready(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Result<(), Self::Error>> {
         self.channel().poll_ready(cx)
     }
 
-    fn start_send(self: Pin<&mut Self>, item: Response<C::Resp>) -> Result<(), Self::Error> {
+    fn start_send(self: Pin<&mut Self>, item: I) -> Result<(), Self::Error> {
         self.channel().start_send(item)
     }
 
@@ -176,6 +150,7 @@ impl<S, K, F> ChannelFilter<S, K, F>
 where
     K: Eq + Hash,
     S: Stream,
+    F: Fn(&S::Item) -> K,
 {
     /// Sheds new channels to stay under configured limits.
     pub(crate) fn new(listener: S, channels_per_key: u32, keymaker: F) -> Self {
@@ -191,23 +166,24 @@ where
     }
 }
 
-impl<S, C, K, F> ChannelFilter<S, K, F>
+impl<S, K, F> ChannelFilter<S, K, F>
 where
-    S: Stream<Item = C>,
-    C: Channel,
+    S: Stream,
     K: fmt::Display + Eq + Hash + Clone + Unpin,
-    F: Fn(&C) -> K,
+    F: Fn(&S::Item) -> K,
 {
-    fn handle_new_channel(self: &mut Pin<&mut Self>, stream: C) -> Result<TrackedChannel<C, K>, K> {
+    fn handle_new_channel(
+        self: &mut Pin<&mut Self>,
+        stream: S::Item,
+    ) -> Result<TrackedChannel<S::Item, K>, K> {
         let key = self.as_mut().keymaker()(&stream);
         let tracker = self.increment_channels_for_key(key.clone())?;
-        let max = self.as_mut().channels_per_key();
 
-        debug!(
+        trace!(
             "[{}] Opening channel ({}/{}) channels for key.",
             key,
             Arc::strong_count(&tracker),
-            max
+            self.as_mut().channels_per_key()
         );
 
         Ok(TrackedChannel {
@@ -256,7 +232,7 @@ where
     fn poll_listener(
         mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
-    ) -> Poll<Option<Result<TrackedChannel<C, K>, K>>> {
+    ) -> Poll<Option<Result<TrackedChannel<S::Item, K>, K>>> {
         match ready!(self.as_mut().listener().poll_next_unpin(cx)) {
             Some(codec) => Poll::Ready(Some(self.handle_new_channel(codec))),
             None => Poll::Ready(None),
@@ -276,19 +252,18 @@ where
     }
 }
 
-impl<S, C, K, F> Stream for ChannelFilter<S, K, F>
+impl<S, K, F> Stream for ChannelFilter<S, K, F>
 where
-    S: Stream<Item = C>,
-    C: Channel,
+    S: Stream,
     K: fmt::Display + Eq + Hash + Clone + Unpin,
-    F: Fn(&C) -> K,
+    F: Fn(&S::Item) -> K,
 {
-    type Item = TrackedChannel<C, K>;
+    type Item = TrackedChannel<S::Item, K>;
 
     fn poll_next(
         mut self: Pin<&mut Self>,
         cx: &mut Context<'_>,
-    ) -> Poll<Option<TrackedChannel<C, K>>> {
+    ) -> Poll<Option<TrackedChannel<S::Item, K>>> {
         loop {
             match (
                 self.as_mut().poll_listener(cx),
@@ -310,3 +285,199 @@ where
         }
     }
 }
+
+#[cfg(test)]
+fn ctx() -> Context<'static> {
+    use futures_test::task::noop_waker_ref;
+
+    Context::from_waker(&noop_waker_ref())
+}
+
+#[test]
+fn tracker_drop() {
+    use assert_matches::assert_matches;
+
+    let (tx, mut rx) = mpsc::unbounded();
+    Tracker {
+        key: Some(1),
+        dropped_keys: tx,
+    };
+    assert_matches!(rx.try_next(), Ok(Some(1)));
+}
+
+#[test]
+fn tracked_channel_stream() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    let (chan_tx, chan) = mpsc::unbounded();
+    let (dropped_keys, _) = mpsc::unbounded();
+    let channel = TrackedChannel {
+        inner: chan,
+        tracker: Arc::new(Tracker {
+            key: Some(1),
+            dropped_keys,
+        }),
+    };
+
+    chan_tx.unbounded_send("test").unwrap();
+    pin_mut!(channel);
+    assert_matches!(channel.poll_next(&mut ctx()), Poll::Ready(Some("test")));
+}
+
+#[test]
+fn tracked_channel_sink() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    let (chan, mut chan_rx) = mpsc::unbounded();
+    let (dropped_keys, _) = mpsc::unbounded();
+    let channel = TrackedChannel {
+        inner: chan,
+        tracker: Arc::new(Tracker {
+            key: Some(1),
+            dropped_keys,
+        }),
+    };
+
+    pin_mut!(channel);
+    assert_matches!(channel.as_mut().poll_ready(&mut ctx()), Poll::Ready(Ok(())));
+    assert_matches!(channel.as_mut().start_send("test"), Ok(()));
+    assert_matches!(channel.as_mut().poll_flush(&mut ctx()), Poll::Ready(Ok(())));
+    assert_matches!(chan_rx.try_next(), Ok(Some("test")));
+}
+
+#[test]
+fn channel_filter_increment_channels_for_key() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (_, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+    let tracker1 = filter.increment_channels_for_key("key").unwrap();
+    assert_eq!(Arc::strong_count(&tracker1), 1);
+    let tracker2 = filter.increment_channels_for_key("key").unwrap();
+    assert_eq!(Arc::strong_count(&tracker1), 2);
+    assert_matches!(filter.increment_channels_for_key("key"), Err("key"));
+    drop(tracker2);
+    assert_eq!(Arc::strong_count(&tracker1), 1);
+}
+
+#[test]
+fn channel_filter_handle_new_channel() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (_, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+    let channel1 = filter
+        .handle_new_channel(TestChannel { key: "key" })
+        .unwrap();
+    assert_eq!(Arc::strong_count(&channel1.tracker), 1);
+
+    let channel2 = filter
+        .handle_new_channel(TestChannel { key: "key" })
+        .unwrap();
+    assert_eq!(Arc::strong_count(&channel1.tracker), 2);
+
+    assert_matches!(
+        filter.handle_new_channel(TestChannel { key: "key" }),
+        Err("key")
+    );
+    drop(channel2);
+    assert_eq!(Arc::strong_count(&channel1.tracker), 1);
+}
+
+#[test]
+fn channel_filter_poll_listener() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (new_channels, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let channel1 =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Ok(c))) => c);
+    assert_eq!(Arc::strong_count(&channel1.tracker), 1);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let _channel2 =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Ok(c))) => c);
+    assert_eq!(Arc::strong_count(&channel1.tracker), 2);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let key =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Err(k))) => k);
+    assert_eq!(key, "key");
+    assert_eq!(Arc::strong_count(&channel1.tracker), 2);
+}
+
+#[test]
+fn channel_filter_poll_closed_channels() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (new_channels, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let channel =
+        assert_matches!(filter.as_mut().poll_listener(&mut ctx()), Poll::Ready(Some(Ok(c))) => c);
+    assert_eq!(filter.key_counts.len(), 1);
+
+    drop(channel);
+    assert_matches!(filter.poll_closed_channels(&mut ctx()), Poll::Ready(()));
+    assert!(filter.key_counts.is_empty());
+}
+
+#[test]
+fn channel_filter_stream() {
+    use assert_matches::assert_matches;
+    use pin_utils::pin_mut;
+
+    #[derive(Debug)]
+    struct TestChannel {
+        key: &'static str,
+    }
+    let (new_channels, listener) = mpsc::unbounded();
+    let filter = ChannelFilter::new(listener, 2, |chan: &TestChannel| chan.key);
+    pin_mut!(filter);
+
+    new_channels
+        .unbounded_send(TestChannel { key: "key" })
+        .unwrap();
+    let channel = assert_matches!(filter.as_mut().poll_next(&mut ctx()), Poll::Ready(Some(c)) => c);
+    assert_eq!(filter.key_counts.len(), 1);
+
+    drop(channel);
+    assert_matches!(filter.as_mut().poll_next(&mut ctx()), Poll::Pending);
+    assert!(filter.key_counts.is_empty());
+}