public void uniqueScreenNames_AddExistingScreenName()
{
initilaizeFilteredTree();
Assert.IsNull(grantTrees.brailleTree);
guiFuctions.addFilteredNodeToBrailleTree("screenName_1", "typeOfView_1", "viewName_1");
Assert.AreEqual(3, strategyMgr.getSpecifiedTree().Count(grantTrees.brailleTree)); // 3 => typeOfView-Node + Screen-Node + View-Node
String idResult = guiFuctions.addFilteredNodeToBrailleTree("screenName_1", "typeOfView_2", "viewName_2"); // Same screenName
Assert.IsNull(idResult);
Assert.AreEqual(3, strategyMgr.getSpecifiedTree().Count(grantTrees.brailleTree)); // the node wasn't added
}