unittests: Fixes unit tests for Windows (part 3)

Currently, there are some unit tests that are failing on Windows due to
various reasons:

- paths not properly joined (filepath.Join should be used).
- Proxy Mode IPVS not supported on Windows.
- DeadlineExceeded can occur when trying to read data from an UDP
  socket. This can be used to detect whether the port was closed or not.
- In Windows, with long file name support enabled, file names can have
  up to 32,767 characters. In this case, the error
  windows.ERROR_FILENAME_EXCED_RANGE will be encountered instead.
- files not closed, which means that they cannot be removed / renamed.
- time.Now() is not as precise on Windows, which means that 2
  consecutive calls may return the same timestamp.
- path.Base() will return the same path. filepath.Base() should be used
  instead.
- path.Join() will always join the paths with a / instead of the OS
  specific separator. filepath.Join() should be used instead.

pkg/volume/util/fs/fs_windows.go

@@ -20,7 +20,6 @@ limitations under the License.
 package fs
 
 import (
-	"fmt"
 	"os"
 	"path/filepath"
 	"syscall"
@@ -105,7 +104,7 @@ func diskUsage(currPath string, info os.FileInfo) (int64, error) {
 
 	for _, file := range files {
 		if file.IsDir() {
-			s, err := diskUsage(fmt.Sprintf("%s/%s", currPath, file.Name()), file)
+			s, err := diskUsage(filepath.Join(currPath, file.Name()), file)
 			if err != nil {
 				return size, err
 			}

pkg/volume/util/fs/fs_windows_test.go

@@ -47,6 +47,12 @@ func TestDiskUsage(t *testing.T) {
 		t.Fatalf("TestDiskUsage failed: %s", err.Error())
 	}
 
+	// File creation is not atomic. If we're calculating the DiskUsage before the data is flushed,
+	// we'd get zeroes for sizes, and fail with this error:
+	// TestDiskUsage failed: expected 0, got -1
+	tmpfile1.Sync()
+	tmpfile2.Sync()
+
 	dirInfo1, err := os.Lstat(dir1)
 	if err != nil {
 		t.Fatalf("TestDiskUsage failed: %s", err.Error())