Run libnetwork test case only when it's specifically enabled

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/libnetwork_test.go

@@ -1,8 +1,8 @@
 package libnetwork_test
 
 import (
+	"flag"
 	"net"
-	"os"
 	"testing"
 
 	log "github.com/Sirupsen/logrus"
@@ -12,17 +12,16 @@ import (
 )
 
 var bridgeName = "docker0"
+var enableBridgeTest = flag.Bool("enable-bridge-test", false, "")
+
+func TestSimplebridge(t *testing.T) {
+	if *enableBridgeTest == false {
+		t.Skip()
+	}
 
-func TestMain(m *testing.M) {
-	// Cleanup any existing docker0 bridge if needed. Ignore errors
 	bridge := &netlink.Bridge{LinkAttrs: netlink.LinkAttrs{Name: bridgeName}}
 	netlink.LinkDel(bridge)
 
-	os.Exit(m.Run())
-}
-
-func TestSimplebridge(t *testing.T) {
-
 	ip, subnet, err := net.ParseCIDR("192.168.100.1/24")
 	if err != nil {
 		t.Fatal(err)