IsSubDomain docs

Improve the docs a little and add a test for when the child and parent
are equal.

defaults.go

@@ -167,8 +167,8 @@ func IsDomainName(s string) (labels int, ok bool) {
 	return labels, err == nil
 }
 
-// IsSubDomain checks if child is indeed a child of the parent. Both child and
-// parent are *not* downcased before doing the comparison.
+// IsSubDomain checks if child is indeed a child of the parent. If child and parent
+// are the same domain true is returned as well.
 func IsSubDomain(parent, child string) bool {
 	// Entire child is contained in parent
 	return CompareDomainName(parent, child) == CountLabel(parent)

dns_test.go

@@ -99,8 +99,9 @@ func TestPackUnpack3(t *testing.T) {
 
 func TestBailiwick(t *testing.T) {
 	yes := map[string]string{
-		"miek.nl": "ns.miek.nl",
-		".":       "miek.nl",
+		"miek1.nl": "miek1.nl",
+		"miek.nl":  "ns.miek.nl",
+		".":        "miek.nl",
 	}
 	for parent, child := range yes {
 		if !IsSubDomain(parent, child) {