diff --git a/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestGraphDBOperation.java b/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestGraphDBOperation.java
new file mode 100644
index 0000000..1a239ed
--- /dev/null
+++ b/src/test/java/net/floodlightcontroller/linkdiscovery/internal/TestGraphDBOperation.java
@@ -0,0 +1,670 @@
+package net.floodlightcontroller.linkdiscovery.internal;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.codehaus.jackson.annotate.JsonIgnore;
+import org.codehaus.jackson.annotate.JsonProperty;
+import org.easymock.EasyMock;
+import org.openflow.util.HexString;
+
+import com.tinkerpop.blueprints.Direction;
+import com.tinkerpop.blueprints.Vertex;
+import com.tinkerpop.frames.Adjacency;
+import com.tinkerpop.frames.Incidence;
+import com.tinkerpop.frames.Property;
+import com.tinkerpop.frames.annotations.gremlin.GremlinGroovy;
+import com.tinkerpop.frames.annotations.gremlin.GremlinParam;
+
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IDeviceObject;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowEntry;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IFlowPath;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.IPortObject;
+import net.onrc.onos.ofcontroller.core.INetMapTopologyObjects.ISwitchObject;
+import net.onrc.onos.ofcontroller.core.ISwitchStorage.SwitchState;
+import net.onrc.onos.ofcontroller.util.FlowEntryId;
+import net.onrc.onos.ofcontroller.util.FlowId;
+import net.onrc.onos.util.GraphDBConnection;
+import net.onrc.onos.util.GraphDBOperation;
+import net.onrc.onos.util.IDBConnection;
+
+public class TestGraphDBOperation extends GraphDBOperation {
+	protected List<TestSwitchObject> switches;
+	protected List<TestPortObject> ports;
+//	protected List<TestDeviceObject> devices;
+//	protected List<TestFlowEntry> flows;
+
+	protected List<TestSwitchObject> switchesToAdd;
+	protected List<TestPortObject> portsToAdd;
+//	protected List<TestDeviceObject> devicesToAdd;
+//	protected List<TestFlowEntry> flowsToAdd;
+
+	protected List<TestSwitchObject> switchesToRemove;
+	protected List<TestPortObject> portsToRemove;
+//	protected List<TestDeviceObject> devicesToRemove;
+//	protected List<TestFlowEntry> flowsToRemove;
+
+
+	// Testable implementations of INetMapTopologyObject interfaces
+	
+	public static class TestSwitchObject implements ISwitchObject {
+		private String state,type,dpid;
+		private List<IPortObject> ports;
+		private List<IDeviceObject> devices;
+		private List<IFlowEntry> flows;
+
+		private String stateToUpdate, typeToUpdate, dpidToUpdate;
+		private List<IPortObject> portsToAdd;
+		private List<IPortObject> portsToRemove;
+
+		public TestSwitchObject() {
+			type = "switch";
+			state = "ACTIVE";
+			
+			ports = new ArrayList<IPortObject>();
+			portsToAdd = new ArrayList<IPortObject>();
+			portsToRemove = new ArrayList<IPortObject>();
+			devices = new ArrayList<IDeviceObject>();
+			flows = new ArrayList<IFlowEntry>();
+			
+			clearUncommitedData();
+		}
+		
+		public void commit() {
+			for(IPortObject port : portsToAdd) {
+				ports.add(port);
+			}
+			for(IPortObject port : portsToRemove) {
+				ports.remove(port);
+			}
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(dpidToUpdate != null) { dpid = dpidToUpdate; }
+
+			clearUncommitedData();
+		}
+		
+		public void rollback() {
+			clearUncommitedData();
+		}
+		
+		public void clearUncommitedData() {
+			portsToAdd.clear();
+			portsToRemove.clear();
+			stateToUpdate = typeToUpdate = dpidToUpdate = null;
+		}
+		
+		public void setDpidForTest(String dpid) { this.dpid = dpid; }
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void addPortForTest(TestPortObject port) { ports.add(port);  }
+		
+		@Override
+		@JsonProperty("state")
+		@Property("state")
+		public String getState() { return state; }
+	
+		@Override
+		@Property("state")
+		public void setState(String state) { this.stateToUpdate = state; }
+	
+		@Override
+		@JsonIgnore
+		@Property("type")
+		public String getType() { return type ; }
+	
+		@Override
+		@Property("type")
+		public void setType(String type) { this.typeToUpdate = type; }
+	
+		// Not support for test
+		@Override
+		public Vertex asVertex() { return null; }
+	
+		@Override
+		@JsonProperty("dpid")
+		@Property("dpid")
+		public String getDPID() { return dpid; }
+	
+		@Override
+		@Property("dpid")
+		public void setDPID(String dpid) { this.dpidToUpdate = dpid; }
+	
+		@Override
+		@JsonProperty("ports")
+		@Adjacency(label = "on")
+		public Iterable<IPortObject> getPorts() { return ports; }
+	
+		@Override
+		@JsonIgnore
+		@GremlinGroovy("_().out('on').has('number',port_num)")
+		public IPortObject getPort(@GremlinParam("port_num") short port_num) {
+			for(IPortObject port : ports) {
+				if(port.getNumber() == port_num) {
+					return port;
+				}
+			}
+			return null;
+		}
+	
+		@Override
+		@Adjacency(label = "on")
+		public void addPort(IPortObject port) { portsToAdd.add(port); }
+	
+		@Override
+		@Adjacency(label = "on")
+		public void removePort(IPortObject port) { portsToRemove.add(port); }
+	
+		@Override
+		@JsonIgnore
+		@GremlinGroovy("_().out('on').out('host')")
+		public Iterable<IDeviceObject> getDevices() { return devices; }
+	
+		@Override
+		@JsonIgnore
+		@Incidence(label = "switch", direction = Direction.IN)
+		public Iterable<IFlowEntry> getFlowEntries() { return flows; }
+	}
+	
+	public static class TestPortObject implements IPortObject {
+		private String state,type,desc;
+		private Short number;
+		private Integer port_state;
+		private ISwitchObject sw;
+		private List<IPortObject> linkedPorts;
+		private List<IDeviceObject> devices;
+		private List<IFlowEntry> flows;
+		
+		private String stateToUpdate,typeToUpdate,descToUpdate;
+		private Short numberToUpdate;
+		private Integer port_stateToUpdate;
+		private List<IPortObject> linkedPortsToAdd;
+		private List<IPortObject> linkedPortsToRemove;
+		
+
+		public TestPortObject() {
+			type = "port";
+			state = "ACTIVE";
+
+			linkedPorts = new ArrayList<IPortObject>();
+			linkedPortsToAdd = new ArrayList<IPortObject>();
+			linkedPortsToRemove = new ArrayList<IPortObject>();
+			devices = new ArrayList<IDeviceObject>();
+			flows = new ArrayList<IFlowEntry>();
+			
+			clearUncommitedData();
+		}
+		
+		public void commit() {
+			for(IPortObject port : linkedPortsToAdd) {
+				linkedPorts.add(port);
+			}
+			for(IPortObject port : linkedPortsToRemove) {
+				linkedPorts.remove(port);
+			}
+			if(stateToUpdate != null) { state = stateToUpdate; }
+			if(typeToUpdate != null) { type = typeToUpdate; }
+			if(descToUpdate != null) { desc = descToUpdate; }
+			if(numberToUpdate != null) { number = numberToUpdate; }
+			if(port_stateToUpdate != null) { port_state = port_stateToUpdate; }
+			
+			clearUncommitedData();
+		}
+		
+		public void rollback() {
+			clearUncommitedData();
+		}
+		
+		public void clearUncommitedData() {
+			linkedPortsToAdd.clear();
+			linkedPortsToRemove.clear();
+			stateToUpdate = typeToUpdate = descToUpdate = null;
+			port_stateToUpdate = null;
+			numberToUpdate = null;
+		}
+		
+		public void setStateForTest(String state) { this.state = state; }
+		public void setTypeForTest(String type) { this.type = type; }
+		public void setDescForTest(String desc) { this.desc = desc; }
+		public void setNumberForTest(Short number) { this.number = number; }
+		public void setPortStateForTest(Integer state) { this.port_state = state; }
+		public void setSwitchForTest(ISwitchObject sw) { this.sw = sw; }
+		public void addLinkedPortForTest(TestPortObject port) { this.linkedPorts.add(port); }
+		
+		@Override
+		@JsonProperty("state")
+		@Property("state")
+		public String getState() { return state; }
+
+		@Override
+		@Property("state")
+		public void setState(String state) { this.stateToUpdate = state; }
+
+		@Override
+		@JsonIgnore
+		@Property("type")
+		public String getType() { return type; }
+
+		@Override
+		@Property("type")
+		public void setType(String type) { this.typeToUpdate = type; }
+
+		// not support for test
+		@Override
+		public Vertex asVertex() {
+			return null;
+		}
+
+		@Override
+		@JsonProperty("number")
+		@Property("number")
+		public Short getNumber() { return number; }
+
+		@Override
+		@Property("number")
+		public void setNumber(Short n) { this.numberToUpdate = n; }
+
+		@Override
+		@JsonProperty("desc")
+		@Property("desc")
+		public String getDesc() { return desc; }
+
+		@Override
+		@Property("desc")
+		public void setDesc(String s) { this.descToUpdate = s; }
+
+		@Override
+		@JsonIgnore
+		@Property("port_state")
+		public Integer getPortState() { return port_state; }
+
+		@Override
+		@Property("port_state")
+		public void setPortState(Integer s) { this.port_stateToUpdate = s; }
+
+		@Override
+		@JsonIgnore
+		@Incidence(label = "on", direction = Direction.IN)
+		public ISwitchObject getSwitch() { return sw; }
+
+		@Override
+		@JsonProperty("devices")
+		@Adjacency(label = "host")
+		public Iterable<IDeviceObject> getDevices() { return devices; }
+
+		@Override
+		@Adjacency(label = "host")
+		public void setDevice(IDeviceObject device) { devices.add(device); }
+
+		@Override
+		@Adjacency(label = "host")
+		public void removeDevice(IDeviceObject device) { devices.remove(device); }
+
+		@Override
+		@JsonIgnore
+		@Incidence(label = "inport", direction = Direction.IN)
+		public Iterable<IFlowEntry> getInFlowEntries() {
+			// TODO Auto-generated method stub
+			return null;
+		}
+
+		@Override
+		@JsonIgnore
+		@Incidence(label = "outport", direction = Direction.IN)
+		public Iterable<IFlowEntry> getOutFlowEntries() {
+			// TODO Auto-generated method stub
+			return null;
+		}
+
+		@Override
+		@JsonIgnore
+		@Adjacency(label = "link")
+		public Iterable<IPortObject> getLinkedPorts() { return linkedPorts; }
+
+		@Override
+		@Adjacency(label = "link")
+		public void removeLink(IPortObject dest_port) { linkedPortsToRemove.add(dest_port); }
+
+		@Override
+		@Adjacency(label = "link")
+		public void setLinkPort(IPortObject dest_port) { linkedPortsToAdd.add(dest_port); }
+	}
+	
+	
+	public TestGraphDBOperation() {
+		super(EasyMock.createNiceMock(GraphDBConnection.class));
+		
+		switches = new ArrayList<TestSwitchObject>();
+		ports = new ArrayList<TestPortObject>();
+//		devices = new ArrayList<TestDeviceObject>();
+//		flows = new ArrayList<TestFlowEntry>();
+		
+		switchesToAdd = new ArrayList<TestSwitchObject>();
+		portsToAdd = new ArrayList<TestPortObject>();
+//		devicesToAdd = new ArrayList<TestDeviceObject>();
+//		flowsToAdd = new ArrayList<TestFlowEntry>();
+
+		switchesToRemove = new ArrayList<TestSwitchObject>();
+		portsToRemove = new ArrayList<TestPortObject>();
+//		devicesToRemove = new ArrayList<TestDeviceObject>();
+//		flowsToRemove = new ArrayList<TestFlowEntry>();
+		
+		clear();
+	}
+	
+	private void clear() {
+		for(TestSwitchObject sw : switches) {
+			sw.clearUncommitedData();
+		}
+		for(TestSwitchObject sw : switchesToAdd) {
+			sw.clearUncommitedData();
+		}
+		
+		for(TestPortObject port : ports) {
+			port.clearUncommitedData();
+		}
+		for(TestPortObject port : portsToAdd) {
+			port.clearUncommitedData();
+		}
+		
+		switchesToAdd.clear();
+		switchesToRemove.clear();
+		portsToAdd.clear();
+		portsToRemove.clear();
+	}
+	
+	
+	// this.*ForTest() methods below are supposed to be used for creation of test topology.
+	/**
+	 * 
+	 * @param dpid
+	 * @return
+	 */
+	public TestSwitchObject createNewSwitchForTest(String dpid) {
+		for(TestSwitchObject sw_loop : switches) {
+			if(sw_loop.getDPID().equals(dpid)) {
+				// Already created
+				return sw_loop;
+			}
+		}
+
+		TestSwitchObject sw = new TestSwitchObject();
+		
+		sw.setDpidForTest(dpid);
+		switches.add(sw);
+		
+		return sw;
+	}
+	
+	public TestPortObject createNewPortForTest(String dpid, Short number) {
+		TestSwitchObject sw = null;
+		
+		for(TestSwitchObject sw_loop : switches) {
+			if(sw_loop.getDPID().equals(dpid)) {
+				sw = sw_loop;
+			}
+		}
+		
+		if(sw != null) {
+			TestPortObject port = new TestPortObject();
+			port.setNumberForTest(number);
+			port.setSwitchForTest(sw);
+
+			return port;
+		} else {
+			return  null;
+		}
+	}
+	
+	public void setLinkBetweenPortsForTest(TestPortObject src, TestPortObject dst) {
+		src.addLinkedPortForTest(dst);
+		//dst.addLinkedPortForTest(src);
+	}
+
+	// Overriding methods below are to mock GraphDBOperation class.
+	@Override
+	public ISwitchObject newSwitch(String dpid) {
+		TestSwitchObject sw = new TestSwitchObject();
+		switchesToAdd.add(sw);
+		
+		return sw;
+	}
+
+	@Override
+	public ISwitchObject searchSwitch(String dpid) {
+		for(ISwitchObject sw : switches) {
+			if(sw.getDPID().equals(dpid)) {
+				return sw;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public ISwitchObject searchActiveSwitch(String dpid) {
+		for(ISwitchObject sw : switches) {
+			if(sw.getDPID().equals(dpid) && sw.getState().equals("ACTIVE")) {
+				return sw;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public Iterable<ISwitchObject> getActiveSwitches() {
+		List<ISwitchObject> list = new ArrayList<ISwitchObject>();
+		
+		for(ISwitchObject sw : switches) {
+			if(sw.getState().equals("ACTIVE")) {
+				list.add(sw);
+			}
+		}
+		return list.isEmpty() ? null : list;
+	}
+
+	@Override
+	public Iterable<ISwitchObject> getAllSwitches() {
+		List<ISwitchObject> list = new ArrayList<ISwitchObject>();
+		
+		for(ISwitchObject sw : switches) {
+			list.add(sw);
+		}
+		
+		return list.isEmpty() ? null : list;
+	}
+
+	@Override
+	public Iterable<ISwitchObject> getInactiveSwitches() {
+		List<ISwitchObject> list = new ArrayList<ISwitchObject>();
+		
+		for(ISwitchObject sw : switches) {
+			if(! sw.getState().equals("ACTIVE")) {
+				list.add(sw);
+			}
+		}
+		return list.isEmpty() ? null : list;
+	}
+
+	@Override
+	public Iterable<IFlowEntry> getAllSwitchNotUpdatedFlowEntries() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public void removeSwitch(ISwitchObject sw) {
+		if(switches.contains(sw)) {
+			switchesToRemove.add((TestSwitchObject)sw);
+		}
+	}
+
+	@Override
+	public IPortObject newPort(Short portNumber) {
+		TestPortObject port = new TestPortObject();
+		port.setNumber(portNumber);
+		
+		return port;
+	}
+
+	public IPortObject newPort(Long dpid, Short portNumber) {
+		TestPortObject port = null;
+		TestSwitchObject sw = (TestSwitchObject)searchSwitch(HexString.toHexString(dpid));
+		
+		if(sw != null) {
+			port = (TestPortObject)newPort(portNumber);
+			portsToAdd.add(port);
+			sw.addPort(port);
+		}
+		
+		return port;
+	}
+	
+	@Override
+	public IPortObject searchPort(String dpid_str, short number) {
+		for(TestSwitchObject sw : switches) {
+			if(sw.getDPID().equals(dpid_str)) {
+				for(IPortObject port : sw.getPorts()) {
+					if(port.getNumber().equals(number)) {
+						return port;
+					}
+				}
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public void removePort(IPortObject port) {
+		for(TestSwitchObject sw : switches) {
+			for(IPortObject pt : sw.getPorts()) {
+				if(pt.equals(port)) {
+					sw.removePort(port);
+				}
+			}
+		}
+		portsToRemove.add((TestPortObject)port);
+	}
+
+	@Override
+	public IDeviceObject newDevice() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public IDeviceObject searchDevice(String macAddr) {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public Iterable<IDeviceObject> getDevices() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public void removeDevice(IDeviceObject dev) {
+		// TODO Auto-generated method stub
+
+	}
+
+	@Override
+	public IFlowPath newFlowPath() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public IFlowPath searchFlowPath(FlowId flowId) {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public IFlowPath getFlowPathByFlowEntry(IFlowEntry flowEntry) {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public Iterable<IFlowPath> getAllFlowPaths() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public void removeFlowPath(IFlowPath flowPath) {
+		// TODO Auto-generated method stub
+
+	}
+
+	@Override
+	public IFlowEntry newFlowEntry() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public IFlowEntry searchFlowEntry(FlowEntryId flowEntryId) {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public Iterable<IFlowEntry> getAllFlowEntries() {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
+	@Override
+	public void removeFlowEntry(IFlowEntry flowEntry) {
+		// TODO Auto-generated method stub
+
+	}
+
+	@Override
+	public IDBConnection getDBConnection() {
+		return super.getDBConnection();
+	}
+
+	@Override
+	public void commit() {
+		for(TestSwitchObject sw : switchesToAdd) {
+			switches.add(sw);
+		}
+		for(TestSwitchObject sw : switchesToRemove) {
+			sw.commit();
+			switches.remove(sw);
+		}
+		for(TestSwitchObject sw : switches) {
+			sw.commit();
+		}
+		
+		for(TestPortObject port : portsToAdd) {
+			ports.add(port);
+		}
+		for(TestPortObject port : portsToRemove) {
+			port.commit();
+			ports.remove(port);
+		}
+		for(TestPortObject port : ports) {
+			port.commit();
+		}
+		
+		clear();
+	}
+
+	@Override
+	public void rollback() {
+		clear();
+	}
+
+	@Override
+	public void close() {
+		// TODO Auto-generated method stub
+
+	}
+}