Added tests for handling incorrectly-reported sequence numbers.

src/test/java/com/relayrides/pushy/apns/ApnsConnectionTest.java

@@ -633,4 +633,53 @@ public void testShutdownAtSendAttemptLimit() throws Exception {
 		this.waitForLatch(limitLatch);
 		assertEquals(notificationCount - sendAttemptLimit, totalLatch.getCount());
 	}
+
+	@Test
+	public void testHandleBogusSequenceNumber() throws Exception {
+		// This covers a weird upstream regression/behavior change where the APNs gateway will send a sequence number of
+		// zero if we send a notification with a zero-length token. See https://github.com/relayrides/pushy/issues/149
+		// for additional discussion.
+
+		this.getApnsServer().setShouldSendIncorrectSequenceNumber(true);
+
+		try {
+			final Object mutex = new Object();
+
+			final TestListener listener = new TestListener(mutex);
+			final ApnsConnection<SimpleApnsPushNotification> apnsConnection =
+					new ApnsConnection<SimpleApnsPushNotification>(
+							TEST_ENVIRONMENT, SSLTestUtil.createSSLContextForTestClient(), this.getEventLoopGroup(),
+							new ApnsConnectionConfiguration(), listener, TEST_CONNECTION_NAME);
+
+			final CountDownLatch latch = this.getApnsServer().getAcceptedNotificationCountDownLatch(1);
+
+			synchronized (mutex) {
+				apnsConnection.connect();
+
+				while (!listener.connectionSucceeded) {
+					mutex.wait();
+				}
+			}
+
+			assertTrue(listener.connectionSucceeded);
+
+			apnsConnection.sendNotification(this.createTestNotification());
+			this.waitForLatch(latch);
+
+			synchronized (mutex) {
+				apnsConnection.shutdownGracefully();
+
+				while (!listener.connectionClosed) {
+					mutex.wait();
+				}
+			}
+
+			assertTrue(listener.connectionClosed);
+			assertNull(listener.rejectedNotification);
+			assertNull(listener.rejectionReason);
+			assertTrue(listener.unprocessedNotifications.isEmpty());
+		} finally {
+			this.getApnsServer().setShouldSendIncorrectSequenceNumber(false);
+		}
+	}
 }

src/test/java/com/relayrides/pushy/apns/MockApnsServer.java

@@ -60,6 +60,7 @@ public class MockApnsServer {
 	private Channel channel;
 
 	private boolean shouldSendErrorResponses = true;
+	private boolean shouldSendIncorrectSequenceNumber = false;
 
 	public static final int EXPECTED_TOKEN_SIZE = 32;
 	public static final int MAX_PAYLOAD_SIZE = 2048;
@@ -292,8 +293,10 @@ public void exceptionCaught(final ChannelHandlerContext context, final Throwable
 				if (decoderException.getCause() instanceof ApnsDecoderException) {
 					if (this.server.shouldSendErrorResponses()) {
 						final ApnsDecoderException apnsDecoderException = (ApnsDecoderException)decoderException.getCause();
+						final int sequenceNumber = this.server.shouldSendIncorrectSequenceNumber ? 0 : apnsDecoderException.sequenceNumber;
+
 						final RejectedNotification rejectedNotification =
-								new RejectedNotification(apnsDecoderException.sequenceNumber, apnsDecoderException.reason);
+								new RejectedNotification(sequenceNumber, apnsDecoderException.reason);
 
 						context.writeAndFlush(rejectedNotification).addListener(ChannelFutureListener.CLOSE);
 					}
@@ -349,6 +352,14 @@ public boolean shouldSendErrorResponses() {
 		return this.shouldSendErrorResponses;
 	}
 
+	public boolean shouldSendIncorrectSequenceNumber() {
+		return shouldSendIncorrectSequenceNumber;
+	}
+
+	public void setShouldSendIncorrectSequenceNumber(boolean shouldSendIncorrectSequenceNumber) {
+		this.shouldSendIncorrectSequenceNumber = shouldSendIncorrectSequenceNumber;
+	}
+
 	private void acceptNotification(final SendableApnsPushNotification<SimpleApnsPushNotification> receivedNotification) {
 		synchronized (this.countdownLatches) {
 			for (final CountDownLatch latch : this.countdownLatches) {