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diff --git a/test/com/isode/stroke/whiteboard/WhiteboardClientTest.java b/test/com/isode/stroke/whiteboard/WhiteboardClientTest.java
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+/*  Copyright (c) 2016, Isode Limited, London, England.
+ *  All rights reserved.
+ *
+ *  Acquisition and use of this software and related materials for any
+ *  purpose requires a written license agreement from Isode Limited,
+ *  or a written license from an organisation licensed by Isode Limited
+ *  to grant such a license.
+ *
+ */
+package com.isode.stroke.whiteboard;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+import org.junit.Test;
+
+import com.isode.stroke.elements.WhiteboardDeleteOperation;
+import com.isode.stroke.elements.WhiteboardElement;
+import com.isode.stroke.elements.WhiteboardEllipseElement;
+import com.isode.stroke.elements.WhiteboardInsertOperation;
+import com.isode.stroke.elements.WhiteboardOperation;
+import com.isode.stroke.elements.WhiteboardUpdateOperation;
+
+
+/**
+ * Tests for {@link WhiteboardClient}
+ */
+public class WhiteboardClientTest {
+
+    /*!
+     *  /\
+     *  \/
+     *   \
+     */
+    @Test
+    public void testSynchronize_simplestSync() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp = createInsertOperation("a", "0", 1);
+        WhiteboardEllipseElement aElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(aElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "a", "0", 1, aElement);
+
+        //Client receives server operation parented off "0", which isn't last client operation
+        //so it have to be transformed against local operations and then transformed value can
+        //be returned to draw
+        serverOp = createInsertOperation("b", "0", 1);
+        WhiteboardEllipseElement bElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(bElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "b", "a", 2, bElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation from the server about processed "a" operation, it had to
+        //be transformed against "b" on the server side to receive operation parented off "b".
+        //There aren't any waiting operations to send to server, this operation should return
+        //nothing
+        serverOp = createInsertOperation("a", "b", 1);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives local operation, it doesn't have to be transformed against anything
+        //but operation returned to send to the server should be parented off last server
+        //operation, which is "b"
+        clientOp = createInsertOperation("c", "b", 3);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(cElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "c", "a", 3, cElement);
+
+        //Client receives confirmation from the server about processed "a" operation, it
+        //should be the same operation as it was sent because server didn't have to
+        //transform it
+        clientOp = createInsertOperation("c", "a", 3);
+        clientOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(clientOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Results:
+        //Client operations:
+        //ID    pos
+        //0     0
+        //a     1
+        //b     2
+        //c     3
+        //
+        //Server operations:
+        //ID    pos
+        //0     0
+        //b     1
+        //a     1
+        //c     3
+        //
+        //what gives 0abc on both sides
+    }
+    
+    /*!
+     *    /
+     *   /
+     *   \
+     */
+    @Test
+    public void testSynchronize_withoutTranslation() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp = createInsertOperation("c", "0", 1);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(cElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "c", "0", 1, cElement);
+
+        //Client receives second local operation, client didn't receive ack about previous
+        //operation from the server so it can't be send.
+        clientOp = createInsertOperation("d", "c", 2);
+        WhiteboardEllipseElement dElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(dElement);
+        assertNull(client.handleLocalOperationReceived(clientOp));
+
+        //Client receives confirmation about processing "c" operation, it should be the
+        //same as sent operation because it wasn't transformed, client could send now
+        //operation "d"
+        clientOp = createInsertOperation("c", "0", 1);
+        clientOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(clientOp);
+        checkOperation(pairResult.server, "d", "c", 2, dElement);
+        assertNull(pairResult.client);
+
+        //Client receives confirmation about processing "d", it should be the same as
+        //sent operation. There aren't any operations in queue to send.
+        clientOp = createInsertOperation("d", "c", 2);
+        clientOp.setElement(dElement);
+        pairResult = client.handleServerOperationReceived(clientOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives new operation from server, it's parented off "d" which is at
+        //the end of local history so it doesn't have to be transformed, so operation
+        //to pass to window should be the same
+        serverOp = createInsertOperation("e", "d", 3);
+        WhiteboardEllipseElement eElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(eElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        WhiteboardInsertOperation result = (WhiteboardInsertOperation) pairResult.client;
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+
+        //Client operations:
+        //ID    pos
+        //0     0
+        //c     1
+        //d     2
+        //e     3
+        //
+        //Server operations:
+        //ID    pos
+        //0     0
+        //c     1
+        //d     2
+        //e     3
+    }
+    
+    /*!
+     *     /\
+     *    /  \
+     *    \  /
+     *     \/
+     */
+    @Test
+    public void testSynchronize_nonInterrupted() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertEquals(null, pairResult.server);
+
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp = createInsertOperation("a", "0", 1);
+        WhiteboardEllipseElement aElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(aElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "a", "0", 1, aElement);
+
+        //Client receives second local operation, client didn't receive ack about previous
+        //operation from the server so it can't be send.
+        clientOp = createInsertOperation("b", "a", 2);
+        WhiteboardEllipseElement bElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(bElement);
+        assertNull(client.handleLocalOperationReceived(clientOp));
+
+        //Client receives new operation from server, it should be transformed against
+        //"a" and "b" before adding to local operations history because it's parented off "0".
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        serverOp = createInsertOperation("c", "0", 1);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "c", "b", 3, cElement);
+        assertNull(pairResult.server);
+
+        //Client receives new operation from server, it should be transformed against
+        //results of previous transformations, returned operation should be parented off
+        //"c" existing in local history.
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        serverOp = createInsertOperation("d", "c", 2);
+        WhiteboardEllipseElement dElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(dElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "d", "c", 4, dElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation about processing "a", it should send next operation
+        //to server which is "b", but it should be version parented of transformed "a"
+        serverOp = createInsertOperation("a", "d", 1);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.server, "b", "a", 2, bElement);
+        assertNull(pairResult.client);
+
+
+        //Client receives confirmation about processing "b", there aren't any operations
+        //waiting so it should return nothing.
+        serverOp = createInsertOperation("b", "a", 2);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client operations:
+        //ID    pos
+        //0     0
+        //a     1
+        //b     2
+        //c     3
+        //d     4
+        //
+        //Server operations:
+        //ID    pos
+        //0     0
+        //c     1
+        //d     2
+        //a     1
+        //b     2
+        //
+        //what gives 0abcd on both sides.
+    }
+    
+    /*!
+     *     /\
+     *    /  \
+     *    \  /
+     *    / /
+     *    \/
+     */
+    @Test
+    public void testSynchronize_clientInterruption() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp = createInsertOperation("a", "0", 1);
+        WhiteboardEllipseElement aElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(aElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "a", "0", 1, aElement);
+
+        //Client receives second local operation, client didn't receive ack about previous
+        //operation from the server so it can't be send.
+        clientOp = createInsertOperation("b", "a", 2);
+        WhiteboardEllipseElement bElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(bElement);
+        assertNull(client.handleLocalOperationReceived(clientOp));
+
+        //Client receives new operation from server, it should be transformed against
+        //"a" and "b" before adding to local operations history because it's parented off "0".
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        serverOp = createInsertOperation("c", "0", 1);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "c", "b", 3, cElement);
+        assertNull(pairResult.server);
+
+        //Client receives new local operation, client is still waiting for ack so, it
+        //should return nothing
+        clientOp = createInsertOperation("e", "a", 4);
+        WhiteboardEllipseElement eElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(eElement);
+        assertNull(client.handleLocalOperationReceived(clientOp));
+
+        //Client receives new server operation, to add it to local history it should be transformed
+        //against result of previous transformations and operation "e", returned operation should
+        //be parented off "e", which was last local operation
+        serverOp = createInsertOperation("d", "c", 2);
+        WhiteboardEllipseElement dElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(dElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "d", "e", 5, dElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation about processing "a", it had to be transformed against
+        //"c" and "d" and it is now parented off "d", returned value should be next operation
+        //which have to be send to server("b" parented off server version of "a").
+        serverOp = createInsertOperation("a", "d", 1);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.server, "b", "a", 2, bElement);
+        assertNull(pairResult.client);
+
+        //Client receives confirmation about processing "b", it is the same operation as sent because
+        //it didn't have to be transformed, returned value should be next operation
+        //which have to be send to server("e" parented off server version of "b").
+        serverOp = createInsertOperation("b", "a", 2);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.server, "e", "b", 4, eElement);
+        assertNull(pairResult.client);
+
+        //Client receives confirmation about processing "b", it is the same operation as sent because
+        //it didn't have to be transformed, there aren't any operations to send so this function returns
+        //nothing
+        serverOp = createInsertOperation("e", "b", 4);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Result:
+        //Client operations:
+        //ID    pos
+        //0     0
+        //a     1
+        //b     2
+        //c     3
+        //e     4
+        //d     5
+        //
+        //Server operations:
+        //0     0
+        //c     1
+        //d     2
+        //a     1
+        //b     2
+        //e     4
+        //what gives 0abced on both sides
+    }
+    
+    /*!
+     *    /\
+     *   / /
+     *   \ \
+     *    \/
+     */
+    @Test
+    public void testSynchronize_serverInterruption() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp = createInsertOperation("a", "0", 1);
+        WhiteboardEllipseElement aElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(aElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "a", "0", 1, aElement);
+
+        //Client receives second local operation, client didn't receive ack about previous
+        //operation from the server so it can't be send.
+        clientOp = createInsertOperation("b", "a", 2);
+        WhiteboardEllipseElement bElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(bElement);
+        assertNull(client.handleLocalOperationReceived(clientOp));
+
+        //Client receives new operation from server, it should be transformed against
+        //"a" and "b" before adding to local operations history because it's parented off "0".
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        serverOp = createInsertOperation("c", "0", 1);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "c", "b", 3, cElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation about processing "a", it had to be transformed against
+        //"c" and it is now parented off "c", returned value should be next operation
+        //which have to be send to server("b" parented off server version of "a").
+        serverOp = createInsertOperation("a", "c", 1);
+        serverOp.setElement(aElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.server, "b", "a", 2, bElement);
+        assertNull(pairResult.client);
+
+        //Client receives new server operation, to add it to local history it should be transformed
+        //against result of previous transformation(but only with transformation of "b"), returned
+        //operation should be parented off "c", which was last local operation
+        serverOp = createInsertOperation("d", "a", 3);
+        WhiteboardEllipseElement dElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(dElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "d", "c", 4, dElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation about processing "b", it had to be transformed against
+        //"d" because both operations was parented off server version of "a".
+        //there aren't any operations to send so this function returns nothing.
+        serverOp = createInsertOperation("b", "d", 2);
+        serverOp.setElement(bElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client operations:
+        //ID    pos
+        //0     0
+        //a     1
+        //b     2
+        //c     3
+        //d     4
+        //
+        //Server operations:
+        //ID    pos
+        //0     0
+        //c     1
+        //a     1
+        //d     3
+        //b     2
+        //
+        //what gives 0abcd on both sides
+    }
+    
+    /*!
+     *     /\
+     *    /  \
+     *    \  /
+     *     \/
+     */
+    @Test
+    public void testSynchronize_nonInterruptedMixOperations() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp = createInsertOperation("a", "0", 1);
+        WhiteboardEllipseElement aElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setElement(aElement);
+        checkOperation(client.handleLocalOperationReceived(clientOp), "a", "0", 1, aElement);
+
+        //Client receives second local operation, client didn't receive ack about previous
+        //operation from the server so it can't be send.
+        WhiteboardUpdateOperation clientUpdateOp = createUpdateOperation("b", "a", 0);
+        WhiteboardEllipseElement bElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientUpdateOp.setElement(bElement);
+        assertNull(client.handleLocalOperationReceived(clientUpdateOp));
+
+        //Client receives new operation from server, it should be transformed against
+        //"a" and "b" before adding to local operations history because it's parented off "0".
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        WhiteboardUpdateOperation serverUpdateOp = createUpdateOperation("c", "0", 0);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverUpdateOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(serverUpdateOp);
+        checkOperation(pairResult.client, "c", "b", 0, cElement);
+        assertNull(pairResult.server);
+
+        //Client receives new operation from server, it should be transformed against
+        //results of previous transformations, returned operation should be parented off
+        //"c" existing in local history.
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        serverOp = createInsertOperation("d", "c", 1);
+        WhiteboardEllipseElement dElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(dElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "d", "c", 2, dElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation about processing "a", it should send next operation
+        //to server which is "b", but it should be version parented of transformed "a"
+        serverOp = createInsertOperation("a", "d", 1);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.server, "b", "a", 0, cElement);
+        assertNull(pairResult.client);
+
+
+        //Client receives confirmation about processing "b", there aren't any operations
+        //waiting so it should return nothing.
+        serverUpdateOp = createUpdateOperation("b", "a", 0);
+        pairResult = client.handleServerOperationReceived(serverUpdateOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client operations:
+        //ID    pos
+        //0     0
+        //a     1
+        //b     2
+        //c     3
+        //d     4
+        //
+        //Server operations:
+        //ID    pos
+        //0     0
+        //c     1
+        //d     2
+        //a     1
+        //b     2
+        //
+        //what gives 0abcd on both sides.
+    }
+    
+    /*!
+     *     /\
+     *    /  \
+     *    \  /
+     *     \/
+     */
+    @Test
+    public void testSynchronize_nonInterruptedMixOperations2() {
+        WhiteboardClient client = new WhiteboardClient();
+        WhiteboardInsertOperation serverOp = createInsertOperation("0", "", 0);
+        WhiteboardClient.Result pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+
+        serverOp = createInsertOperation("1", "0", 1);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        assertEquals(serverOp, pairResult.client);
+        assertNull(pairResult.server);
+        //Client receives first local operation, because it's parented off "0" which exists
+        //in server history and client doesn't wait for any operation ack from server,
+        //so this operation could be send
+        WhiteboardInsertOperation clientOp;
+        WhiteboardUpdateOperation clientUpdateOp;
+        WhiteboardDeleteOperation clientDeleteOp;
+        clientUpdateOp = createUpdateOperation("a", "1", 0);
+        WhiteboardEllipseElement aElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientUpdateOp.setElement(aElement);
+        checkOperation(client.handleLocalOperationReceived(clientUpdateOp), "a", "1", 0, aElement);
+
+        //Client receives second local operation, client didn't receive ack about previous
+        //operation from the server so it can't be send.
+        clientDeleteOp = createDeleteOperation("b", "a", 1);
+        assertNull(client.handleLocalOperationReceived(clientDeleteOp));
+
+        //Client receives new operation from server, it should be transformed against
+        //"a" and "b" before adding to local operations history because it's parented off "0".
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        serverOp = createInsertOperation("c", "1", 2);
+        WhiteboardEllipseElement cElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverOp.setElement(cElement);
+        pairResult = client.handleServerOperationReceived(serverOp);
+        checkOperation(pairResult.client, "c", "b", 1, cElement);
+        assertNull(pairResult.server);
+
+        //Client receives new operation from server, it should be transformed against
+        //results of previous transformations, returned operation should be parented off
+        //"c" existing in local history.
+        //Because client is waiting for ack of "a", there is no operation to send to server
+        WhiteboardUpdateOperation serverUpdateOp = createUpdateOperation("d", "c", 0);
+        WhiteboardEllipseElement dElement = new WhiteboardEllipseElement(0,0,0,0);
+        serverUpdateOp.setElement(dElement);
+        pairResult = client.handleServerOperationReceived(serverUpdateOp);
+        checkOperation(pairResult.client, "d", "c", 0, dElement);
+        assertNull(pairResult.server);
+
+        //Client receives confirmation about processing "a", it should send next operation
+        //to server which is "b", but it should be version parented of transformed "a"
+        serverUpdateOp = createUpdateOperation("a", "d", 0);
+        pairResult = client.handleServerOperationReceived(serverUpdateOp);
+        checkOperation(pairResult.server, "b", "a", 1);
+        assertNull(pairResult.client);
+
+
+        //Client receives confirmation about processing "b", there aren't any operations
+        //waiting so it should return nothing.
+        WhiteboardDeleteOperation serverDeleteOp = createDeleteOperation("b", "a", 0);
+        pairResult = client.handleServerOperationReceived(serverDeleteOp);
+        assertNull(pairResult.client);
+        assertNull(pairResult.server);
+
+        //Client operations:
+        //ID    pos
+        //0     0
+        //a     1
+        //b     2
+        //c     3
+        //d     4
+        //
+        //Server operations:
+        //ID    pos
+        //0     0
+        //c     1
+        //d     2
+        //a     1
+        //b     2
+        //
+        //what gives 0abcd on both sides.
+    }
+    
+    private WhiteboardInsertOperation createInsertOperation(String id, String parent, int pos) {
+        WhiteboardInsertOperation operation = new WhiteboardInsertOperation();
+        operation.setParentID(parent);
+        operation.setID(id);
+        operation.setPos(pos);
+        return operation;
+    }
+
+    private WhiteboardUpdateOperation createUpdateOperation(String id, String parent, int pos) {
+        WhiteboardUpdateOperation operation = new WhiteboardUpdateOperation();
+        operation.setParentID(parent);
+        operation.setID(id);
+        operation.setPos(pos);
+        return operation;
+    }
+
+    private WhiteboardDeleteOperation createDeleteOperation(String id, String parent, int pos) {
+        WhiteboardDeleteOperation operation = new WhiteboardDeleteOperation();
+        operation.setParentID(parent);
+        operation.setID(id);
+        operation.setPos(pos);
+        return operation;
+    }
+    
+    private void checkOperation(WhiteboardOperation operation, String id, String parent) {
+        checkOperation(operation,id,parent,-1);
+    }
+
+    private void checkOperation(WhiteboardOperation operation, String id, String parent, int pos) {
+       checkOperation(operation,id,parent,pos,null);
+    }
+    
+    private void checkOperation(WhiteboardOperation operation, String id, String parent, int pos, WhiteboardElement element) {
+        assertEquals(id, operation.getID());
+        assertEquals(parent, operation.getParentID());
+        if (pos != -1) {
+            assertEquals(pos, operation.getPos());
+        }
+
+        if (element != null) {
+            if (operation instanceof WhiteboardInsertOperation) {
+                WhiteboardInsertOperation insertOp = (WhiteboardInsertOperation) operation;
+                assertEquals(element,insertOp.getElement());
+            }
+            else if (operation instanceof WhiteboardUpdateOperation) {
+                WhiteboardUpdateOperation updateOp = (WhiteboardUpdateOperation) operation;
+                assertEquals(element,updateOp.getElement());
+            }
+        }
+    }
+
+}
diff --git a/test/com/isode/stroke/whiteboard/WhiteboardServerTest.java b/test/com/isode/stroke/whiteboard/WhiteboardServerTest.java
new file mode 100644
index 0000000..c90d8c3
--- /dev/null
+++ b/test/com/isode/stroke/whiteboard/WhiteboardServerTest.java
@@ -0,0 +1,146 @@
+/*  Copyright (c) 2016, Isode Limited, London, England.
+ *  All rights reserved.
+ *
+ *  Acquisition and use of this software and related materials for any
+ *  purpose requires a written license agreement from Isode Limited,
+ *  or a written license from an organisation licensed by Isode Limited
+ *  to grant such a license.
+ *
+ */
+package com.isode.stroke.whiteboard;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import com.isode.stroke.elements.WhiteboardDeleteOperation;
+import com.isode.stroke.elements.WhiteboardEllipseElement;
+import com.isode.stroke.elements.WhiteboardInsertOperation;
+import com.isode.stroke.elements.WhiteboardOperation;
+import com.isode.stroke.elements.WhiteboardUpdateOperation;
+
+/**
+ * Tests for {@link WhiteboardServer}
+ */
+public class WhiteboardServerTest {
+
+    @Test
+    public void testSimpleOp() {
+        WhiteboardServer server = new WhiteboardServer();
+        WhiteboardInsertOperation firstOp = new WhiteboardInsertOperation();
+        firstOp.setID("0");
+        server.handleLocalOperationReceived(firstOp);
+        WhiteboardInsertOperation serverOp = new WhiteboardInsertOperation();
+        serverOp.setID("b");
+        serverOp.setParentID("0");
+        serverOp.setPos(1);
+        server.handleLocalOperationReceived(serverOp);
+        WhiteboardInsertOperation clientOp = new WhiteboardInsertOperation();
+        WhiteboardEllipseElement clientElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setID("a");
+        clientOp.setParentID("0");
+        clientOp.setPos(1);
+        clientOp.setElement(clientElement);
+        WhiteboardOperation resultOp = server.handleClientOperationReceived(clientOp);
+        assertNotNull(resultOp);
+        assertTrue("resultOp is not a WhiteboardInsertOperation",
+                resultOp instanceof WhiteboardInsertOperation);
+        WhiteboardInsertOperation op = (WhiteboardInsertOperation) resultOp;
+        assertEquals("b",op.getParentID());
+        assertEquals("a",op.getID());
+        assertEquals(1,op.getPos());
+        assertEquals(clientElement,op.getElement());
+    }
+    
+    @Test
+    public void testSimpleOp1() {
+        WhiteboardServer server = new WhiteboardServer();
+        WhiteboardInsertOperation firstOp = new WhiteboardInsertOperation();
+        firstOp.setID("0");
+        server.handleLocalOperationReceived(firstOp);
+        WhiteboardDeleteOperation serverOp = new WhiteboardDeleteOperation();
+        serverOp.setID("b");
+        serverOp.setParentID("0");
+        serverOp.setPos(1);
+        server.handleLocalOperationReceived(serverOp);
+        WhiteboardUpdateOperation clientOp = new WhiteboardUpdateOperation();
+        WhiteboardEllipseElement clientElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setID("a");
+        clientOp.setParentID("0");
+        clientOp.setPos(1);
+        clientOp.setElement(clientElement);
+        WhiteboardOperation resultOp = server.handleClientOperationReceived(clientOp);
+        assertNotNull(resultOp);
+        assertTrue("resultOp is not a WhiteboardDeleteOperation",
+                resultOp instanceof WhiteboardDeleteOperation);
+        WhiteboardDeleteOperation op = (WhiteboardDeleteOperation) resultOp;
+        assertEquals("b", op.getParentID());
+        assertEquals("a", op.getID());
+        assertEquals(-1, op.getPos());
+    }
+    
+    @Test
+    public void testSimpleOp2() {
+        WhiteboardServer server = new WhiteboardServer();
+        WhiteboardInsertOperation firstOp = new WhiteboardInsertOperation();
+        firstOp.setID("0");
+        server.handleLocalOperationReceived(firstOp);
+        WhiteboardUpdateOperation serverOp = new WhiteboardUpdateOperation();
+        serverOp.setID("b");
+        serverOp.setParentID("0");
+        serverOp.setPos(1);
+        server.handleLocalOperationReceived(serverOp);
+        WhiteboardDeleteOperation clientOp = new WhiteboardDeleteOperation();
+        clientOp.setID("a");
+        clientOp.setParentID("0");
+        clientOp.setPos(1);
+        WhiteboardOperation resultOp = server.handleClientOperationReceived(clientOp);
+        assertNotNull(resultOp);
+        assertTrue("resultOp is not a WhiteboardDeleteOperation",
+                resultOp instanceof WhiteboardDeleteOperation);
+        WhiteboardDeleteOperation op = (WhiteboardDeleteOperation) resultOp;
+        assertEquals("b", op.getParentID());
+        assertEquals("a", op.getID());
+        assertEquals(1, op.getPos());
+    }
+    
+    @Test
+    public void testFewSimpleOps() {
+        WhiteboardServer server = new WhiteboardServer();
+        WhiteboardInsertOperation firstOp = new WhiteboardInsertOperation();
+        firstOp.setID("0");
+        server.handleLocalOperationReceived(firstOp);
+        WhiteboardInsertOperation serverOp = new WhiteboardInsertOperation();
+        serverOp.setID("a");
+        serverOp.setParentID("0");
+        serverOp.setPos(1);
+        server.handleLocalOperationReceived(serverOp);
+        serverOp = new WhiteboardInsertOperation();
+        serverOp.setID("b");
+        serverOp.setParentID("a");
+        serverOp.setPos(2);
+        server.handleLocalOperationReceived(serverOp);
+        serverOp = new WhiteboardInsertOperation();
+        serverOp.setID("c");
+        serverOp.setParentID("b");
+        serverOp.setPos(3);
+        server.handleLocalOperationReceived(serverOp);
+        WhiteboardInsertOperation clientOp = new WhiteboardInsertOperation();
+        WhiteboardEllipseElement clientElement = new WhiteboardEllipseElement(0,0,0,0);
+        clientOp.setID("d");
+        clientOp.setParentID("0");
+        clientOp.setPos(1);
+        clientOp.setElement(clientElement);
+        WhiteboardOperation resultOp = server.handleClientOperationReceived(clientOp);
+        assertNotNull(resultOp);
+        assertTrue("resultOp is not a WhiteboardInsertOperation",resultOp instanceof WhiteboardInsertOperation);
+        WhiteboardInsertOperation op = (WhiteboardInsertOperation) resultOp;
+        assertEquals("c", op.getParentID());
+        assertEquals("d", op.getID());
+        assertEquals(1, op.getPos());
+        assertEquals(clientElement, op.getElement());
+    }
+
+}