Index: test/org/openstreetmap/josm/test/MergeVisitorTest.java
===================================================================
--- test/org/openstreetmap/josm/test/MergeVisitorTest.java	(revision 52)
+++ test/org/openstreetmap/josm/test/MergeVisitorTest.java	(revision 52)
@@ -0,0 +1,36 @@
+package org.openstreetmap.josm.test;
+
+import junit.framework.TestCase;
+
+import org.openstreetmap.josm.data.GeoPoint;
+import org.openstreetmap.josm.data.osm.DataSet;
+import org.openstreetmap.josm.data.osm.LineSegment;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.data.osm.visitor.MergeVisitor;
+import org.openstreetmap.josm.test.framework.DataSetTestCaseHelper;
+
+public class MergeVisitorTest extends TestCase {
+
+	
+	/**
+	 * Merge of an old line segment with a new one. This should
+	 * be mergable (if the nodes matches).
+	 */
+	public void testMergeOldLineSegmentsWithNew() {
+		DataSet ds = new DataSet();
+		Node n1 = DataSetTestCaseHelper.createNode(ds);
+		n1.id = 1;
+		Node n2 = DataSetTestCaseHelper.createNode(ds);
+		n2.id = 2;
+		LineSegment ls1 = DataSetTestCaseHelper.createLineSegment(ds, n1, n2);
+		ls1.id = 3;
+
+		Node newnode = new Node();
+		newnode.coor = new GeoPoint(n2.coor.lat, n2.coor.lon);
+		LineSegment newls = new LineSegment(n1, newnode);
+
+		MergeVisitor v = new MergeVisitor(ds);
+		v.visit(newls);
+		assertEquals("line segment should have been merged.", 1, ds.lineSegments.size());
+	}
+}
Index: test/org/openstreetmap/josm/test/framework/DataSetTestCaseHelper.java
===================================================================
--- test/org/openstreetmap/josm/test/framework/DataSetTestCaseHelper.java	(revision 49)
+++ test/org/openstreetmap/josm/test/framework/DataSetTestCaseHelper.java	(revision 52)
@@ -43,5 +43,5 @@
 	 * Create a line segment with out of the given nodes.
 	 */
-	private static LineSegment createLineSegment(DataSet ds, Node n1, Node n2) {
+	public static LineSegment createLineSegment(DataSet ds, Node n1, Node n2) {
 		LineSegment ls = new LineSegment(n1, n2);
 		ds.lineSegments.add(ls);
@@ -52,5 +52,5 @@
 	 * Add a random node.
 	 */
-	private static Node createNode(DataSet ds) {
+	public static Node createNode(DataSet ds) {
 		Node node = new Node();
 		node.coor = new GeoPoint(Math.random(), Math.random());