Tests for HandledNode (#546)

* Add unit tests for core::nodes::NodeStream

* Move DummyMuxer to core/tests

* Address grumbles

* Impl Debug for SubstreamRef<P>

* Add test for poll()

* Don't need to open a substream

* pretty printer test

* More tests for NodeStream poll()

* ListenerStream unit tests: transport() and listeners()

* Tests for nodes/listeners.rs

* Add a few tests to help illustrate the "drowning" behaviour of busy listeners

* Tests for HandledNode

* Address grumbles

* Remove non-project specific stuff

* Address grumbles

* Prefer freestanding function

* Untangle the code for old shutdown test from the new tests
Add HandlerState and use it in TestBuilder
Shorter test names

* WIP – tests pass

* Use a newtype to lighten up the function signatures a bit
Test NotReady case

* Cleanup Event enum
Track events as they reach the Handler
Describe complex test logic

* Assert on the event trace

* More tests for poll()

* Switch to using usize as the OutboundOpenInfo so we can assert on event contents
More tests for poll()

* whitespace

* Move Handler related code to dummy_handler

* Fixes broken test after upstream changes

* Clarify the behaviour of is_shutting_down

* Fix broken test

* Fix tests after recent changes on master

* no tabs

* whitespace

* rustfmt

* Add public HandledNode.handler() method that returns a ref to the NodeHandler
Don't use private members in tests

* Add HandledNode.handler_mut that returns a mutable ref to the NodeHandler

* Remove debugging stmts

* Fix parse error

core/src/nodes/handled_node.rs

@@ -65,7 +65,7 @@ pub trait NodeHandler {
     /// Injects an event coming from the outside into the handler.
     fn inject_event(&mut self, event: Self::InEvent);
 
-    /// Indicates that the node that it should shut down. After that, it is expected that `poll()`
+    /// Indicates to the node that it should shut down. After that, it is expected that `poll()`
     /// returns `Ready(None)` as soon as possible.
     ///
     /// This method allows an implementation to perform a graceful shutdown of the substreams, and
@@ -176,6 +176,16 @@ where
         }
     }
 
+    /// Returns a reference to the `NodeHandler`
+    pub fn handler(&self) -> &THandler{
+        &self.handler
+    }
+
+    /// Returns a mutable reference to the `NodeHandler`
+    pub fn handler_mut(&mut self) -> &mut THandler{
+        &mut self.handler
+    }
+
     /// Injects an event to the handler.
     #[inline]
     pub fn inject_event(&mut self, event: THandler::InEvent) {
@@ -286,7 +296,6 @@ where
                 }
             }
         }
-
         Ok(Async::NotReady)
     }
 }
@@ -294,44 +303,81 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
-    use muxing::{StreamMuxer, Shutdown};
-    use std::marker::PhantomData;
     use tokio::runtime::current_thread;
+    use tests::dummy_muxer::{DummyMuxer, DummyConnectionState};
+    use tests::dummy_handler::{Handler, HandlerState, Event};
+    use std::marker::PhantomData;
 
-    // TODO: move somewhere? this could be useful as a dummy
-    struct InstaCloseMuxer;
-    impl StreamMuxer for InstaCloseMuxer {
-        type Substream = ();
-        type OutboundSubstream = ();
-        fn poll_inbound(&self) -> Poll<Option<Self::Substream>, IoError> { Ok(Async::Ready(None)) }
-        fn open_outbound(&self) -> Self::OutboundSubstream { () }
-        fn poll_outbound(&self, _: &mut Self::OutboundSubstream) -> Poll<Option<Self::Substream>, IoError> { Ok(Async::Ready(None)) }
-        fn destroy_outbound(&self, _: Self::OutboundSubstream) {}
-        fn read_substream(&self, _: &mut Self::Substream, _: &mut [u8]) -> Poll<usize, IoError> { panic!() }
-        fn write_substream(&self, _: &mut Self::Substream, _: &[u8]) -> Poll<usize, IoError> { panic!() }
-        fn flush_substream(&self, _: &mut Self::Substream) -> Poll<(), IoError> { panic!() }
-        fn shutdown_substream(&self, _: &mut Self::Substream, _: Shutdown) -> Poll<(), IoError> { panic!() }
-        fn destroy_substream(&self, _: Self::Substream) { panic!() }
-        fn shutdown(&self, _: Shutdown) -> Poll<(), IoError> { Ok(Async::Ready(())) }
-        fn flush_all(&self) -> Poll<(), IoError> { Ok(Async::Ready(())) }
+    // Concrete `HandledNode`
+    type TestHandledNode = HandledNode<DummyMuxer, Handler>;
+
+    struct TestBuilder {
+        muxer: DummyMuxer,
+        handler: Handler,
+        want_open_substream: bool,
+        substream_user_data: usize,
+    }
+
+    impl TestBuilder {
+        fn new() -> Self {
+            TestBuilder {
+                muxer: DummyMuxer::new(),
+                handler: Handler::default(),
+                want_open_substream: false,
+                substream_user_data: 0,
+            }
+        }
+
+        fn with_muxer_inbound_state(&mut self, state: DummyConnectionState) -> &mut Self {
+            self.muxer.set_inbound_connection_state(state);
+            self
+        }
+
+        fn with_muxer_outbound_state(&mut self, state: DummyConnectionState) -> &mut Self {
+            self.muxer.set_outbound_connection_state(state);
+            self
+        }
+
+        fn with_handler_state(&mut self, state: HandlerState) -> &mut Self {
+            self.handler.state = Some(state);
+            self
+        }
+
+        fn with_open_substream(&mut self, user_data: usize) -> &mut Self {
+            self.want_open_substream = true;
+            self.substream_user_data = user_data;
+            self
+        }
+
+        fn handled_node(&mut self) -> TestHandledNode {
+            let mut h = HandledNode::new(self.muxer.clone(), self.handler.clone());
+            if self.want_open_substream {
+                h.node.get_mut().open_substream(self.substream_user_data).expect("open substream should work");
+            }
+            h
+        }
+    }
+
+    // Set the state of the `Handler` after `inject_outbound_closed` is called
+    fn set_next_handler_outbound_state( handled_node: &mut TestHandledNode, next_state: HandlerState) {
+        handled_node.handler.next_outbound_state = Some(next_state);
     }
 
     #[test]
     fn proper_shutdown() {
-        // Test that `shutdown()` is properly called on the handler once a node stops.
-        struct Handler<T> {
+        struct ShutdownHandler<T> {
             did_substream_attempt: bool,
             inbound_closed: bool,
             substream_attempt_cancelled: bool,
             shutdown_called: bool,
-            marker: PhantomData<T>,
-        };
-        impl<T> NodeHandler for Handler<T> {
+            marker: PhantomData<T>
+        }
+        impl<T> NodeHandler for ShutdownHandler<T> {
             type InEvent = ();
             type OutEvent = ();
             type Substream = T;
             type OutboundOpenInfo = ();
-            fn inject_substream(&mut self, _: T, _: NodeHandlerEndpoint<()>) { panic!() }
+            fn inject_substream(&mut self, _: Self::Substream, _: NodeHandlerEndpoint<Self::OutboundOpenInfo>) { panic!() }
             fn inject_inbound_closed(&mut self) {
                 assert!(!self.inbound_closed);
                 self.inbound_closed = true;
@@ -357,13 +403,20 @@ mod tests {
                 }
             }
         }
-        impl<T> Drop for Handler<T> {
+
+        impl<T> Drop for ShutdownHandler<T> {
             fn drop(&mut self) {
-                assert!(self.shutdown_called);
+                if self.did_substream_attempt {
+                    assert!(self.shutdown_called);
+                }
             }
         }
 
-        let handled = HandledNode::new(InstaCloseMuxer, Handler {
+        // Test that `shutdown()` is properly called on the handler once a node stops.
+        let mut muxer = DummyMuxer::new();
+        muxer.set_inbound_connection_state(DummyConnectionState::Closed);
+        muxer.set_outbound_connection_state(DummyConnectionState::Closed);
+        let handled = HandledNode::new(muxer, ShutdownHandler {
             did_substream_attempt: false,
             inbound_closed: false,
             substream_attempt_cancelled: false,
@@ -373,4 +426,227 @@ mod tests {
 
         current_thread::Runtime::new().unwrap().block_on(handled.for_each(|_| Ok(()))).unwrap();
     }
+
+    #[test]
+    fn can_inject_event() {
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Closed)
+            .handled_node();
+
+        let event = Event::Custom("banana");
+        handled.inject_event(event.clone());
+        assert_eq!(handled.handler().events, vec![event]);
+    }
+
+    #[test]
+    fn knows_if_inbound_is_closed() {
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Closed)
+            .with_handler_state(HandlerState::Ready(None)) // or we get into an infinite loop
+            .handled_node();
+        handled.poll().expect("poll failed");
+        assert!(!handled.is_inbound_open())
+    }
+
+    #[test]
+    fn knows_if_outbound_is_closed() {
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            .with_muxer_outbound_state(DummyConnectionState::Closed)
+            .with_handler_state(HandlerState::Ready(None)) // or we get into an infinite loop
+            .with_open_substream(987) // without at least one substream we do not poll_outbound so we never get the event
+            .handled_node();
+
+        handled.poll().expect("poll failed");
+        assert!(!handled.is_outbound_open());
+    }
+
+    #[test]
+    fn is_shutting_down_is_true_when_called_shutdown_on_the_handled_node() {
+        let mut handled = TestBuilder::new()
+            .with_handler_state(HandlerState::Ready(None)) // Stop the loop towards the end of the first run
+            .handled_node();
+        assert!(!handled.is_shutting_down());
+        handled.poll().expect("poll should work");
+        handled.shutdown();
+        assert!(handled.is_shutting_down());
+    }
+
+    #[test]
+    fn is_shutting_down_is_true_when_in_and_outbounds_are_closed() {
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Closed)
+            .with_muxer_outbound_state(DummyConnectionState::Closed)
+            .with_open_substream(123) // avoid infinite loop
+            .handled_node();
+
+        handled.poll().expect("poll should work");
+
+        // Shutting down (in- and outbound are closed, and the handler is shutdown)
+        assert!(handled.is_shutting_down());
+    }
+
+    #[test]
+    fn is_shutting_down_is_true_when_handler_is_gone() {
+        // when in-/outbound NodeStreams are  open or Async::Ready(None) we reach the handlers `poll()` and initiate shutdown.
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            .with_muxer_outbound_state(DummyConnectionState::Pending)
+            .with_handler_state(HandlerState::Ready(None)) // avoid infinite loop
+            .handled_node();
+
+        handled.poll().expect("poll should work");
+
+        assert!(handled.is_shutting_down());
+    }
+
+    #[test]
+    fn is_shutting_down_is_true_when_handler_is_gone_even_if_in_and_outbounds_are_open() {
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Opened)
+            .with_muxer_outbound_state(DummyConnectionState::Opened)
+            .with_open_substream(123)
+            .with_handler_state(HandlerState::Ready(None))
+            .handled_node();
+
+        handled.poll().expect("poll should work");
+
+        assert!(handled.is_shutting_down());
+    }
+
+    #[test]
+    fn poll_with_unready_node_stream_polls_handler() {
+        let mut handled = TestBuilder::new()
+            // make NodeStream return NotReady
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            // make Handler return return Ready(None) so we break the infinite loop
+            .with_handler_state(HandlerState::Ready(None))
+            .handled_node();
+
+        assert_matches!(handled.poll(), Ok(Async::Ready(None)));
+    }
+
+    #[test]
+    fn poll_with_unready_node_stream_and_handler_emits_custom_event() {
+        let expected_event = Some(NodeHandlerEvent::Custom(Event::Custom("pineapple")));
+        let mut handled = TestBuilder::new()
+            // make NodeStream return NotReady
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            // make Handler return return Ready(Some(…))
+            .with_handler_state(HandlerState::Ready(expected_event))
+            .handled_node();
+
+        assert_matches!(handled.poll(), Ok(Async::Ready(Some(event))) => {
+            assert_matches!(event, Event::Custom("pineapple"))
+        });
+    }
+
+    #[test]
+    fn handler_emits_outbound_closed_when_opening_new_substream_on_closed_node() {
+        let open_event = Some(NodeHandlerEvent::OutboundSubstreamRequest(456));
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            .with_muxer_outbound_state(DummyConnectionState::Closed)
+            .with_handler_state(HandlerState::Ready(open_event))
+            .handled_node();
+
+        set_next_handler_outbound_state(
+            &mut handled,
+            HandlerState::Ready(Some(NodeHandlerEvent::Custom(Event::Custom("pear"))))
+        );
+        handled.poll().expect("poll works");
+        assert_eq!(handled.handler().events, vec![Event::OutboundClosed]);
+    }
+
+    #[test]
+    fn poll_returns_not_ready_when_node_stream_and_handler_is_not_ready() {
+        let mut handled = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Closed)
+            .with_muxer_outbound_state(DummyConnectionState::Closed)
+            .with_open_substream(12)
+            .with_handler_state(HandlerState::NotReady)
+            .handled_node();
+
+        // Under the hood, this is what happens when calling `poll()`:
+        // - we reach `node.poll_inbound()` and because the connection is
+        //   closed, `inbound_finished` is set to true.
+        // - an Async::Ready(NodeEvent::InboundClosed) is yielded (also calls
+        //   `inject_inbound_close`, but that's irrelevant here)
+        // - back in `poll()` we cal `handler.poll()` which does nothing because
+        //   `HandlerState` is `NotReady`: loop continues
+        // - polls the node again which now skips the inbound block because
+        //   `inbound_finished` is true.
+        // - Now `poll_outbound()` is called which returns `Async::Ready(None)`
+        //   and sets `outbound_finished` to true. …calls destroy_outbound and
+        //   yields Ready(OutboundClosed) …so the HandledNode calls
+        //   `inject_outbound_closed`.
+        // - Now we have `inbound_finished` and `outbound_finished` set (and no
+        //   more outbound substreams).
+        // - Next we poll the handler again which again does nothing because
+        //   HandlerState is NotReady (and the node is still there)
+        // - HandledNode polls the node again: we skip inbound and there are no
+        //   more outbound substreams so we skip that too; the addr is now
+        //   Resolved so that part is skipped too
+        // - We reach the last section and the NodeStream yields Async::Ready(None)
+        // - Back in HandledNode the Async::Ready(None) triggers a shutdown
+        // – …and causes the Handler to yield Async::Ready(None)
+        // – which in turn makes the HandledNode to yield Async::Ready(None) as well
+        assert_matches!(handled.poll(), Ok(Async::Ready(None)));
+        assert_eq!(handled.handler().events, vec![
+            Event::InboundClosed, Event::OutboundClosed
+        ]);
+    }
+
+    #[test]
+    fn poll_yields_inbound_closed_event() {
+        let mut h = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Closed)
+            .with_handler_state(HandlerState::Err) // stop the loop
+            .handled_node();
+
+        assert_eq!(h.handler().events, vec![]);
+        let _ = h.poll();
+        assert_eq!(h.handler().events, vec![Event::InboundClosed]);
+    }
+
+    #[test]
+    fn poll_yields_outbound_closed_event() {
+        let mut h = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            .with_open_substream(32)
+            .with_muxer_outbound_state(DummyConnectionState::Closed)
+            .with_handler_state(HandlerState::Err) // stop the loop
+            .handled_node();
+
+        assert_eq!(h.handler().events, vec![]);
+        let _ = h.poll();
+        assert_eq!(h.handler().events, vec![Event::OutboundClosed]);
+    }
+
+    #[test]
+    fn poll_yields_outbound_substream() {
+        let mut h = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Pending)
+            .with_muxer_outbound_state(DummyConnectionState::Opened)
+            .with_open_substream(1)
+            .with_handler_state(HandlerState::Err) // stop the loop
+            .handled_node();
+
+        assert_eq!(h.handler().events, vec![]);
+        let _ = h.poll();
+        assert_eq!(h.handler().events, vec![Event::Substream(Some(1))]);
+    }
+
+    #[test]
+    fn poll_yields_inbound_substream() {
+        let mut h = TestBuilder::new()
+            .with_muxer_inbound_state(DummyConnectionState::Opened)
+            .with_muxer_outbound_state(DummyConnectionState::Pending)
+            .with_handler_state(HandlerState::Err) // stop the loop
+            .handled_node();
+
+        assert_eq!(h.handler().events, vec![]);
+        let _ = h.poll();
+        assert_eq!(h.handler().events, vec![Event::Substream(None)]);
+    }
 }