for the control down test only supply one host

only supply one host to the control down event test so that it is a
deterministic host which goes down.

events_ccm_test.go

@@ -41,22 +41,25 @@ func TestEventDiscovery(t *testing.T) {
 
 func TestEventNodeDownControl(t *testing.T) {
 	const targetNode = "node1"
-	t.Log("marking " + targetNode + " as down")
 	if err := ccm.AllUp(); err != nil {
 		t.Fatal(err)
 	}
 
-	session := createSession(t)
+	status, err := ccm.Status()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cluster := createCluster()
+	cluster.Hosts = []string{status[targetNode].Addr}
+	session := createSessionFromCluster(cluster, t)
 	defer session.Close()
 
+	t.Log("marking " + targetNode + " as down")
 	if err := ccm.NodeDown(targetNode); err != nil {
 		t.Fatal(err)
 	}
 
-	status, err := ccm.Status()
-	if err != nil {
-		t.Fatal(err)
-	}
 	t.Logf("status=%+v\n", status)
 	t.Logf("marking node %q down: %v\n", targetNode, status[targetNode])