Added more unit tests for a few small things.

+package org.onlab.onos.net.topology;
+
+import com.google.common.testing.EqualsTester;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+import static org.onlab.onos.net.topology.ClusterId.clusterId;
+
+/**
+ * Test of the cluster ID.
+ */
+public class ClusterIdTest {
+
+    @Test
+    public void testEquals() {
+        new EqualsTester()
+                .addEqualityGroup(clusterId(1), clusterId(1))
+                .addEqualityGroup(clusterId(3), clusterId(3)).testEquals();
+    }
+
+    @Test
+    public void basics() {
+        assertEquals("incorrect index", 123, clusterId(123).index());
+    }
+
+}
\ No newline at end of file

+package org.onlab.onos.net.topology;
+
+import com.google.common.testing.EqualsTester;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.onlab.onos.net.DeviceId.deviceId;
+import static org.onlab.onos.net.topology.ClusterId.clusterId;
+
+/**
+ * Test of the default topology cluster implementation.
+ */
+public class DefaultTopologyClusterTest {
+
+    @Test
+    public void testEquals() {
+        new EqualsTester()
+                .addEqualityGroup(cluster(3, 2, 1, "of:1"), cluster(3, 2, 1, "of:1"))
+                .addEqualityGroup(cluster(3, 2, 1, "of:2"), cluster(3, 2, 1, "of:2"))
+                .addEqualityGroup(cluster(0, 2, 1, "of:1"), cluster(0, 2, 1, "of:1"))
+                .addEqualityGroup(cluster(3, 3, 1, "of:1"), cluster(3, 3, 1, "of:1"))
+                .testEquals();
+    }
+
+    @Test
+    public void basics() {
+        TopologyCluster cluster = cluster(6, 5, 4, "of:111");
+        assertEquals("incorrect id", clusterId(6), cluster.id());
+        assertEquals("incorrect id", 5, cluster.deviceCount());
+        assertEquals("incorrect id", 4, cluster.linkCount());
+        assertEquals("incorrect id", deviceId("of:111"), cluster.root());
+
+    }
+
+    private TopologyCluster cluster(int id, int dc, int lc, String root) {
+        return new DefaultTopologyCluster(clusterId(id), dc, lc, deviceId(root));
+    }
+}
\ No newline at end of file