Improves ping responder

Patch contains several bugfixes and improvements:
- Fixes sid retrieval when the destination leaf is down
- Fixes sid retrieval when ping goes through the spine
- Fixes MPLS deserializer
- Improves Ethernet toString
- Fixes ping to looback for dh host when bond sends to wrong leaf

Change-Id: I05963e74b2976e526826ffd377cadeb462ba0a8d
diff --git a/app/src/test/java/org/onosproject/segmentrouting/MockPacketService.java b/app/src/test/java/org/onosproject/segmentrouting/MockPacketService.java
new file mode 100644
index 0000000..73a8b65
--- /dev/null
+++ b/app/src/test/java/org/onosproject/segmentrouting/MockPacketService.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2019-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.segmentrouting;
+
+import com.google.common.collect.Maps;
+import org.apache.commons.lang3.tuple.Pair;
+import org.onlab.packet.DeserializationException;
+import org.onlab.packet.Ethernet;
+import org.onlab.packet.MacAddress;
+import org.onosproject.net.packet.OutboundPacket;
+import org.onosproject.net.packet.PacketServiceAdapter;
+
+import java.util.Map;
+
+/**
+ * Mock Packet Service.
+ * It is used for tests related to packet-ins management.
+ */
+public class MockPacketService extends PacketServiceAdapter {
+
+    private final Map<MacAddress, Pair<OutboundPacket, Ethernet>> outBoundPackets = Maps.newHashMap();
+
+    @Override
+    public void emit(OutboundPacket packet) {
+        try {
+            Ethernet ethernetPacket = Ethernet.deserializer().deserialize(packet.data().array(),
+                                                                          packet.data().arrayOffset(),
+                                                                          packet.data().array().length);
+            outBoundPackets.put(ethernetPacket.getDestinationMAC(), Pair.of(packet, ethernetPacket));
+        } catch (DeserializationException e) {
+
+        }
+    }
+
+    Ethernet getEthernetPacket(MacAddress key) {
+        Pair<OutboundPacket, Ethernet> pair = outBoundPackets.get(key);
+        return pair != null ? pair.getRight() : null;
+    }
+}