ipList = set.NewStringSet()
	for _, ip := range mustGetLocalIPs() {
		if ip != nil && ip.IsLoopback() {
			ipList.Add(ip.String())
		}
	}
	return ipList
}

// mustGetLocalIP4 returns IPv4 addresses of localhost.  It panics on error.
func mustGetLocalIP4() (ipList set.StringSet) {
	ipList = set.NewStringSet()
	for _, ip := range mustGetLocalIPs() {
		if ip.To4() != nil {
			ipList.Add(ip.String())
		}
	}
	return ipList

func TestMustGetLocalIP4(t *testing.T) {
	testCases := []struct {
		expectedIPList set.StringSet
	}{
		{set.CreateStringSet("127.0.0.1")},
	}

	for _, testCase := range testCases {
		ipList := mustGetLocalIP4()
		if testCase.expectedIPList != nil && testCase.expectedIPList.Intersection(ipList).IsEmpty() {
			t.Fatalf("host: expected = %v, got = %v", testCase.expectedIPList, ipList)
		}
	}
}