Skip tests if not root (#12)

This should allow running locally without requiring capabilities flags
or root. Note that I'm not actually checking for capabilities and just
for uid = 0 to determine if I should skip or not.

nl/down_test.go

@@ -1,12 +1,18 @@
 package nl
 
 import (
+	"os"
 	"testing"
 
 	"github.com/vishvananda/netlink"
 )
 
 func TestDownInterface(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("Test requires root or network capabilities - skipped")
+		return
+	}
+
 	CreateTestInterface("lyft3")
 	defer RemoveInterface("lyft3")
 
@@ -20,6 +26,11 @@ func TestDownInterface(t *testing.T) {
 }
 
 func TestRemoveInterface(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("Test requires root or network capabilities - skipped")
+		return
+	}
+
 	CreateTestInterface("lyft4")
 
 	if err := RemoveInterface("lyft4"); err != nil {

nl/up_test.go

@@ -2,6 +2,7 @@ package nl
 
 import (
 	"fmt"
+	"os"
 	"testing"
 
 	"github.com/vishvananda/netlink"
@@ -24,6 +25,11 @@ func CreateTestInterface(name string) {
 }
 
 func TestUpInterface(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("Test requires root or network capabilities - skipped")
+		return
+	}
+
 	CreateTestInterface("lyft1")
 	defer RemoveInterface("lyft1")
 
@@ -33,6 +39,11 @@ func TestUpInterface(t *testing.T) {
 }
 
 func TestUpInterfacePoll(t *testing.T) {
+	if os.Getuid() != 0 {
+		t.Skip("Test requires root or network capabilities - skipped")
+		return
+	}
+
 	CreateTestInterface("lyft2")
 	defer RemoveInterface("lyft2")