Index: trunk/test/unit/org/openstreetmap/josm/data/osm/OsmPrimitiveTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/data/osm/OsmPrimitiveTest.java	(revision 2407)
+++ trunk/test/unit/org/openstreetmap/josm/data/osm/OsmPrimitiveTest.java	(revision 2407)
@@ -0,0 +1,112 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.data.osm;
+
+import java.util.Arrays;
+import java.util.HashSet;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class OsmPrimitiveTest {
+
+    private void compareReferrers(OsmPrimitive actual, OsmPrimitive... expected) {
+        Assert.assertEquals(new HashSet<OsmPrimitive>(Arrays.asList(expected)),
+                new HashSet<OsmPrimitive>(actual.getReferrers()));
+    }
+
+    private DataSet dataSet = new DataSet();
+
+    @Test
+    public void simpleReferrersTest() {
+        Node n1 = new Node();
+        Way w1 = new Way();
+        w1.addNode(n1);
+        dataSet.addPrimitive(n1);
+        dataSet.addPrimitive(w1);
+        compareReferrers(n1, w1);
+    }
+
+    @Test
+    public void addAndRemoveReferrer() {
+        Node n1 = new Node();
+        Node n2 = new Node();
+        Way w1 = new Way();
+        w1.addNode(n1);
+        w1.addNode(n2);
+        w1.addNode(n1);
+        w1.removeNode(n1);
+        dataSet.addPrimitive(n1);
+        dataSet.addPrimitive(n2);
+        dataSet.addPrimitive(w1);
+        compareReferrers(n1);
+        compareReferrers(n2, w1);
+    }
+
+    @Test
+    public void multipleReferrers() {
+        Node n1 = new Node();
+        Way w1 = new Way();
+        Way w2 = new Way();
+        Relation r1 = new Relation();
+        w1.addNode(n1);
+        w2.addNode(n1);
+        r1.addMember(new RelationMember("", n1));
+        dataSet.addPrimitive(n1);
+        dataSet.addPrimitive(w1);
+        dataSet.addPrimitive(w2);
+        dataSet.addPrimitive(r1);
+        compareReferrers(n1, w1, w2, r1);
+    }
+
+    @Test
+    public void removeMemberFromRelationReferrerTest() {
+        Node n1 = new Node();
+        Relation r1 = new Relation();
+        r1.addMember(new RelationMember("", n1));
+        r1.addMember(new RelationMember("", n1));
+        r1.removeMember(0);
+        dataSet.addPrimitive(n1);
+        dataSet.addPrimitive(r1);
+        compareReferrers(n1, r1);
+    }
+
+    @Test
+    public void setRelationMemberReferrerTest() {
+        Node n1 = new Node();
+        Node n2 = new Node();
+        Relation r1 = new Relation();
+        Relation r2 = new Relation();
+        r1.addMember(new RelationMember("", n1));
+        r2.addMember(new RelationMember("", n2));
+        r2.setMember(0, r1.getMember(0));
+        dataSet.addPrimitive(n1);
+        dataSet.addPrimitive(n2);
+        dataSet.addPrimitive(r1);
+        dataSet.addPrimitive(r2);
+        compareReferrers(n1, r1, r2);
+        compareReferrers(n2);
+    }
+
+    @Test
+    public void removePrimitiveReferrerTest() {
+        Node n1 = new Node();
+        Way w1 = new Way();
+        w1.addNode(n1);
+        w1.setDeleted(true);
+        dataSet.addPrimitive(n1);
+        compareReferrers(n1);
+        w1.setDeleted(false);
+        dataSet.addPrimitive(w1);
+
+        compareReferrers(n1, w1);
+
+        Relation r1 = new Relation();
+        r1.addMember(new RelationMember("", w1));
+        r1.setDeleted(true);
+        dataSet.addPrimitive(r1);
+        compareReferrers(w1);
+        r1.setDeleted(false);
+        compareReferrers(w1, r1);
+    }
+
+}