fix: Add a thread-safe logBuffer for the watchdog unit test.

Author: zhifei92

pkg/kubelet/watchdog/watchdog_linux_test.go

@@ -25,6 +25,7 @@ import (
 	"flag"
 	"net/http"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -139,14 +140,7 @@ func TestHealthCheckerStart(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			// Capture logs
-			var logBuffer bytes.Buffer
-			flags := &flag.FlagSet{}
-			klog.InitFlags(flags)
-			if err := flags.Set("v", "5"); err != nil {
-				t.Fatal(err)
-			}
-			klog.LogToStderr(false)
-			klog.SetOutput(&logBuffer)
+			logBuffer := setupLogging(t)
 
 			// Mock SdWatchdogEnabled to return a valid value
 			mockClient := &mockWatchdogClient{
@@ -178,3 +172,38 @@ func TestHealthCheckerStart(t *testing.T) {
 		})
 	}
 }
+
+// threadSafeBuffer is a thread-safe wrapper around bytes.Buffer.
+type threadSafeBuffer struct {
+	buffer bytes.Buffer
+	mu     sync.Mutex
+}
+
+func (b *threadSafeBuffer) Write(p []byte) (n int, err error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buffer.Write(p)
+}
+
+func (b *threadSafeBuffer) String() string {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	return b.buffer.String()
+}
+
+// setupLogging sets up logging to capture output using a thread-safe buffer.
+func setupLogging(t *testing.T) *threadSafeBuffer {
+	flags := &flag.FlagSet{}
+	klog.InitFlags(flags)
+	if err := flags.Set("v", "5"); err != nil {
+		t.Fatal(err)
+	}
+	klog.LogToStderr(false)
+
+	logBuffer := &threadSafeBuffer{}
+
+	// Set the output to the thread-safe buffer
+	klog.SetOutput(logBuffer)
+
+	return logBuffer
+}