* dnsforward: refactor code for default DNS servers logic

dnsforward/dnsforward_test.go

@@ -16,8 +16,8 @@ import (
 
 	"github.com/AdguardTeam/AdGuardHome/dnsfilter"
 	"github.com/AdguardTeam/dnsproxy/proxy"
-	"github.com/likexian/gokit/assert"
 	"github.com/miekg/dns"
+	"github.com/stretchr/testify/assert"
 )
 
 const (
@@ -391,7 +391,7 @@ func createTestServer(t *testing.T) *Server {
 	s := NewServer(f, nil, nil)
 	s.conf.UDPListenAddr = &net.UDPAddr{Port: 0}
 	s.conf.TCPListenAddr = &net.TCPAddr{Port: 0}
-
+	s.conf.UpstreamDNS = []string{"8.8.8.8:53", "8.8.4.4:53"}
 	s.conf.FilteringConfig.ProtectionEnabled = true
 	return s
 }