[ECO-5700] fix: ensure channel state updates before connection state listeners notify (RTL3d1)

lib/src/main/java/io/ably/lib/transport/ConnectionManager.java

@@ -603,13 +603,15 @@ protected void setState() {
 
         protected void enactState() {
             if(change != null) {
+                // RTL3d1: implement the state change first, so channel states are updated
+                // before listeners observe the new connection state
+                states.get(stateIndication.state).enact(stateIndication, change);
+
                 if(change.current != change.previous) {
                     /* broadcast currentState change */
                     connection.onConnectionStateChange(change);
                 }
 
-                /* implement the state change */
-                states.get(stateIndication.state).enact(stateIndication, change);
                 if(currentState.terminal) {
                     clearTransport();
                 }

lib/src/test/java/io/ably/lib/test/realtime/RealtimeChannelTest.java

@@ -7,9 +7,9 @@
 import io.ably.lib.realtime.ChannelEvent;
 import io.ably.lib.realtime.ChannelState;
 import io.ably.lib.realtime.ChannelStateListener;
+import io.ably.lib.realtime.ConnectionEvent;
 import io.ably.lib.realtime.CompletionListener;
 import io.ably.lib.realtime.ConnectionState;
-import io.ably.lib.realtime.ConnectionStateListener;
 import io.ably.lib.test.common.Helpers;
 import io.ably.lib.test.common.Helpers.ChannelWaiter;
 import io.ably.lib.test.common.Helpers.ConnectionWaiter;
@@ -37,6 +37,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
@@ -2128,13 +2129,10 @@ public void channel_attach_retry_failed() {
             ably.connection.connectionManager.requestState(ConnectionState.suspended);
             channelWaiter.waitFor(ChannelState.suspended);
 
-            /* Reconnect and immediately block transport's send(). This should fail channel reattach */
-            ably.connection.once(ConnectionState.connected, new ConnectionStateListener() {
-                @Override
-                public void onConnectionStateChanged(ConnectionStateChange state) {
-                    mockTransport.blockSend();
-                }
-            });
+            /* Block transport's send() before reconnecting so that channel reattach fails.
+             * (Channel transitions to attaching before the connected event fires, so send
+             * must be blocked before requestState is called.) */
+            mockTransport.blockSend();
             ably.connection.connectionManager.requestState(ConnectionState.connected);
 
             /* Channel should move to attaching state */
@@ -2594,7 +2592,21 @@ public void release_should_not_prevent_graceful_test_end() throws Exception {
             Thread.sleep(100);
         }
 
-        assertFalse("Found orphan Timer threads", timers.stream().anyMatch(Thread::isAlive));
+        String activeTimers = timers.stream()
+            .filter(Thread::isAlive)
+            .map(this::stringStackTrace)
+            .collect(Collectors.joining("\n\n"));
+
+        assertFalse(
+            "Found orphan Timer threads:\n" + activeTimers,
+            timers.stream().anyMatch(Thread::isAlive)
+        );
+    }
+
+    private String stringStackTrace(Thread thread) {
+        return Arrays.stream(thread.getStackTrace())
+            .map(StackTraceElement::toString)
+            .collect(Collectors.joining("\n"));
     }
 
     /**
@@ -2640,6 +2652,56 @@ public void channel_get_objects_throws_exception() throws AblyException {
         }
     }
 
+    /*
+     * @spec RTL3d1
+     *
+     * Given: an attached channel
+     * When: the connection drops and then reconnects
+     * Then: at the moment the connection fires onConnected, the channel state is already attaching
+     */
+    @Test
+    public void channel_state_is_attaching_on_reconnected() throws AblyException {
+        ClientOptions opts = createOptions(testVars.keys[0].keyStr);
+        AblyRealtime ably = new AblyRealtime(opts);
+        ConnectionWaiter connectionWaiter = new ConnectionWaiter(ably.connection);
+
+        /* attach channel and wait for it to be fully attached */
+        final Channel channel = ably.channels.get("channel_state_is_attaching_on_reconnected_" + testParams.name);
+        ChannelWaiter channelWaiter = new ChannelWaiter(channel);
+        channel.attach();
+        channelWaiter.waitFor(ChannelState.attached);
+        assertEquals("Channel should be attached", ChannelState.attached, channel.state);
+
+        /* capture channel state at the moment the connection becomes connected */
+        final ChannelState[] channelStateOnConnected = new ChannelState[1];
+
+        /* drop the connection */
+        new Helpers.MutableConnectionManager(ably).disconnectAndSuppressRetries();
+        connectionWaiter.waitFor(ConnectionState.disconnected);
+        assertEquals("Connection should be disconnected", ConnectionState.disconnected, ably.connection.state);
+
+        Helpers.CompletionWaiter completionWaiter = new Helpers.CompletionWaiter();
+
+        ably.connection.on(ConnectionEvent.connected, stateChange -> {
+            synchronized (channelStateOnConnected) {
+                channelStateOnConnected[0] = channel.state;
+                completionWaiter.onSuccess();
+            }
+        });
+
+        /* reconnect */
+        ably.connection.connect();
+
+        completionWaiter.waitFor();
+
+        /* verify channel was attaching at the moment the connection became connected */
+        assertEquals(
+            "Channel state should be attaching when connection fires connected",
+            ChannelState.attaching,
+            channelStateOnConnected[0]
+        );
+    }
+
     static class DetachingProtocolListener implements DebugOptions.RawProtocolListener {
 
         public Channel theChannel;