Replace NewObjectBackupStore with interface (#3329)

In preparation for modifying the instantiation of `BackupStores` to be
able to load credentials, change the function `NewObjectBackupStore` to
be an interface that is passed in to all controllers.

Previously, the function to get a new backup store was configurable but
for many controllers was fixed to use `NewObjectBackupStore`. This
change introduces an interface for getting the backup store and wraps
the functionality from `NewObjectBackupStore` in a type which implements
this interface. This will allow more flexibility when introducing
credentials for a specific backup store as it will allow us to create a
new `ObjectBackupStoreGetter` type which can be configured to add
credentials config when creating the ObjectBackupStore without needing
to change the API used by the controllers.

Signed-off-by: Bridget McErlean <bmcerlean@vmware.com>

pkg/controller/backup_sync_controller_test.go

@@ -21,6 +21,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/vmware-tanzu/velero/pkg/persistence"
+
 	"github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -34,7 +36,6 @@ import (
 	"github.com/vmware-tanzu/velero/pkg/generated/clientset/versioned/fake"
 	informers "github.com/vmware-tanzu/velero/pkg/generated/informers/externalversions"
 	"github.com/vmware-tanzu/velero/pkg/label"
-	"github.com/vmware-tanzu/velero/pkg/persistence"
 	persistencemocks "github.com/vmware-tanzu/velero/pkg/persistence/mocks"
 	"github.com/vmware-tanzu/velero/pkg/plugin/clientmgmt"
 	pluginmocks "github.com/vmware-tanzu/velero/pkg/plugin/mocks"
@@ -351,14 +352,10 @@ func TestBackupSyncControllerRun(t *testing.T) {
 				nil, // kubeClient
 				"",
 				func(logrus.FieldLogger) clientmgmt.Manager { return pluginManager },
+				NewFakeObjectBackupStoreGetter(backupStores),
 				velerotest.NewLogger(),
 			).(*backupSyncController)
 
-			c.newBackupStore = func(loc *velerov1api.BackupStorageLocation, _ persistence.ObjectStoreGetter, _ logrus.FieldLogger) (persistence.BackupStore, error) {
-				// this gets populated just below, prior to exercising the method under test
-				return backupStores[loc.Name], nil
-			}
-
 			pluginManager.On("CleanupClients").Return(nil)
 
 			for _, location := range test.locations {
@@ -576,6 +573,7 @@ func TestDeleteOrphanedBackups(t *testing.T) {
 				nil, // kubeClient
 				"",
 				nil, // new plugin manager func
+				persistence.NewObjectBackupStoreGetter(),
 				velerotest.NewLogger(),
 			).(*backupSyncController)
 
@@ -669,6 +667,7 @@ func TestStorageLabelsInDeleteOrphanedBackups(t *testing.T) {
 				nil, // kubeClient
 				"",
 				nil, // new plugin manager func
+				persistence.NewObjectBackupStoreGetter(),
 				velerotest.NewLogger(),
 			).(*backupSyncController)