wrapped ServerLeaseCounter into an interface and added a unit test fo…

…r the ServerCount() method in clientset

pkg/agent/clientset.go

@@ -39,7 +39,7 @@ type ClientSet struct {
 	agentID string // ID of this agent
 	address string // proxy server address. Assuming HA proxy server
 
-	leaseCounter            *ServerLeaseCounter // counts number of proxy server leases
+	leaseCounter            ServerCounter // counts number of proxy server leases
 	lastReceivedServerCount int                 // last server count received from a proxy server
 	lastServerCount         int                 // last server count value from either lease system or proxy server, former takes priority
 
@@ -147,7 +147,7 @@ type ClientSetConfig struct {
 	WarnOnChannelLimit      bool
 	SyncForever             bool
 	XfrChannelSize          int
-	ServerLeaseCounter      *ServerLeaseCounter
+	ServerLeaseCounter      ServerCounter
 }
 
 func (cc *ClientSetConfig) NewAgentClientSet(drainCh, stopCh <-chan struct{}) *ClientSet {

pkg/agent/clientset_test.go

@@ -0,0 +1,75 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package agent
+
+import (
+	"testing"
+)
+
+type FakeServerCounter struct {
+	count int
+}
+
+func (f *FakeServerCounter) Count() int {
+	return f.count
+}
+
+func TestServerCount(t *testing.T) {
+	testCases := []struct{
+		name string
+		responseCount int
+		leaseCount int
+		want int
+	} {
+		{
+			name: "higher from response",
+			responseCount: 42,
+			leaseCount: 24,
+			want: 42,
+		},
+		{
+			name: "higher from leases",
+			responseCount: 3,
+			leaseCount: 6,
+			want: 6,
+		},
+		{
+			name: "both zero",
+			responseCount: 0,
+			leaseCount: 0,
+			want: 1,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			lc := &FakeServerCounter{
+				count: tc.leaseCount,
+			}
+
+			cs := &ClientSet{
+				clients: make(map[string]*Client),
+				leaseCounter: lc,
+			}
+			cs.lastReceivedServerCount = tc.responseCount
+			if got := cs.ServerCount(); got != tc.want {
+				t.Errorf("cs.ServerCount() = %v, want: %v", got, tc.want)
+			}
+		})
+	}
+
+}

pkg/agent/lease_counter.go

@@ -36,6 +36,10 @@ import (
 	coordinationv1lister "k8s.io/client-go/listers/coordination/v1"
 )
 
+type ServerCounter interface {
+	Count() int
+}
+
 // A ServerLeaseCounter counts leases in the k8s apiserver to determine the
 // current proxy server count.
 type ServerLeaseCounter struct {