fixed some unit tests

rate.go

@@ -15,10 +15,11 @@ import (
 )
 
 const (
-	maxQPSPerNameserver  = 250
-	numIntervalSeconds   = 2
-	rateUpdateInterval   = numIntervalSeconds * time.Second
-	maxTimeoutPercentage = 0.5
+	startQPSPerNameserver = 15
+	maxQPSPerNameserver   = 250
+	numIntervalSeconds    = 2
+	rateUpdateInterval    = numIntervalSeconds * time.Second
+	maxTimeoutPercentage  = 0.5
 )
 
 type rateTrack struct {
@@ -52,8 +53,8 @@ func NewRateTracker() *RateTracker {
 
 func newRateTrack() *rateTrack {
 	return &rateTrack{
-		qps:  maxQPSPerNameserver,
-		rate: ratelimit.New(maxQPSPerNameserver),
+		qps:  startQPSPerNameserver,
+		rate: ratelimit.New(startQPSPerNameserver),
 	}
 }
 
@@ -135,6 +136,9 @@ func (rt *rateTrack) update() {
 		}
 	} else {
 		rt.qps += 1
+		if rt.qps > maxQPSPerNameserver {
+			rt.qps = maxQPSPerNameserver
+		}
 	}
 	// update the QPS rate limiter and reset counters
 	rt.rate = ratelimit.New(rt.qps)

rate_test.go

@@ -21,12 +21,14 @@ func TestUpdateRateLimiters(t *testing.T) {
 	tracker.Lock()
 	qps := tracker.qps
 	tracker.Unlock()
-	num := qps / 2
+	num := qps / 3
 	// set a large number of timeouts
 	for i := 0; i < num; i++ {
 		rt.Success(domain)
 	}
-	for i := 0; i < num; i++ {
+
+	max := tracker.qps - num
+	for i := 0; i < max; i++ {
 		rt.Timeout(domain)
 	}
 	time.Sleep(rateUpdateInterval + (rateUpdateInterval / 2))

resolvers_test.go

@@ -29,7 +29,7 @@ func TestInitializeResolver(t *testing.T) {
 
 func TestSetTimeout(t *testing.T) {
 	r := NewResolvers()
-	_ = r.AddResolvers(1000, "8.8.8.8")
+	_ = r.AddResolvers(maxQPSPerNameserver, "8.8.8.8")
 	defer r.Stop()
 
 	timeout := 2 * time.Second

selector.go

@@ -44,8 +44,14 @@ func (r *randomSelector) GetResolver() *resolver {
 	r.Lock()
 	defer r.Unlock()
 
+	if l := len(r.list); l == 0 {
+		return nil
+	} else if l == 1 {
+		return r.list[0]
+	}
+
 	var chosen *resolver
-	sel := rand.Intn(len(r.list) + 1)
+	sel := rand.Intn(len(r.list))
 loop:
 	for _, res := range r.list[sel:] {
 		select {