Enhance hot upgrade tests

Signed-off-by: Zephyr <zinsist777@gmail.com>

Author: Zephyrcf

smoke/tests/takeover_test.go

@@ -27,7 +27,7 @@ import (
 // Prepare: setup nydus for containerd, reference: https://github.com/dragonflyoss/nydus/blob/master/docs/containerd-env-setup.md.
 
 const (
-	HotUpgradeRepeatCount = 6
+	hotUpgradeRepeatCount = 6
 	configPath            = "/etc/nydus/config.toml"
 )
 
@@ -100,7 +100,7 @@ func (f *TakeoverTestSuit) TestAPIHotUpgrade(t *testing.T) {
 	tool.RunContainerSimple(t, imageName, snapshotter, containerName, false)
 	defer f.rmContainer(containerName)
 
-	//api trigger hot upgrade nydusd
+	// api trigger hot upgrade nydusd
 	for i := 0; i < HotUpgradeRepeatCount; i++ {
 		nydusdPath := nydusdPaths[i%2]
 		logrus.Debugf("API hot upgrade round %d, nydusd_path = %s", i+1, nydusdPath)
@@ -128,7 +128,7 @@ func (f *TakeoverTestSuit) TestRestartSnapshotterHotUpgrade(t *testing.T) {
 	tool.RunContainerSimple(t, imageName, snapshotter, containerName, false)
 	defer f.rmContainer(containerName)
 
-	//restart snapshotter trigger hot upgrade nydusd
+	// restart snapshotter trigger hot upgrade nydusd
 	for i := 0; i < HotUpgradeRepeatCount; i++ {
 		nydusdPath := nydusdPaths[i%2]
 		logrus.Debugf("Restart hot upgrade round %d, nydusd_path = %s", i+1, nydusdPath)