test: improved kubelet disk_manager coverage.

pkg/kubelet/disk_manager.go

@@ -28,6 +28,9 @@ import (
 
 // Manages policy for diskspace management for disks holding docker images and root fs.
 
+// mb is used to easily convert an int to an mb
+const mb = 1024 * 1024
+
 // Implementation is thread-safe.
 type diskSpaceManager interface {
 	// Checks the available disk space
@@ -107,8 +110,6 @@ func (dm *realDiskSpaceManager) isSpaceAvailable(fsType string, threshold int, f
 		return true, fmt.Errorf("wrong available space for %q: %+v", fsType, fsInfo)
 	}
 
-	const mb = int64(1024 * 1024)
-
 	if fsInfo.Available < int64(threshold)*mb {
 		glog.Infof("Running out of space on disk for %q: available %d MB, threshold %d MB", fsType, fsInfo.Available/mb, threshold)
 		return false, nil