testCases := []struct {
		volumeName     string
		prefix         string
		expectedResult []string
		expectErr      bool
	}{
		{"foo", "path", []string{"to/"}, false},
		// prefix not found error.
		{"foo", "nodir", nil, true},
	}

	for i, testCase := range testCases {
		result, err := storage.ListDir(context.Background(), "", testCase.volumeName, testCase.prefix, -1)
		expectErr := (err != nil)