face: Implementing forgotten isListening() feature in TcpChannel

Change-Id: Idfcd8337d16b414d2f739f936660dffdce413729
diff --git a/tests/face/tcp.cpp b/tests/face/tcp.cpp
index d908804..6fe74e4 100644
--- a/tests/face/tcp.cpp
+++ b/tests/face/tcp.cpp
@@ -169,9 +169,13 @@
   shared_ptr<TcpChannel> channel1 = factory.createChannel("127.0.0.1", "20070");
   factory.createChannel("127.0.0.1", "20071");
 
+  BOOST_CHECK_EQUAL(channel1->isListening(), false);
+
   channel1->listen(bind(&EndToEndFixture::channel1_onFaceCreated,   this, _1),
                    bind(&EndToEndFixture::channel1_onConnectFailed, this, _1));
 
+  BOOST_CHECK_EQUAL(channel1->isListening(), true);
+
   factory.createFace(FaceUri("tcp://127.0.0.1:20070"),
                      bind(&EndToEndFixture::channel2_onFaceCreated, this, _1),
                      bind(&EndToEndFixture::channel2_onConnectFailed, this, _1));