Add fake filesystem for test to avoid temporal files on the local filesystem

internal/watch/dummy.go

@@ -0,0 +1,29 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package watch
+
+// DummyFileWatcher noop implementation of a file watcher
+type DummyFileWatcher struct{}
+
+func NewDummyFileWatcher(file string, onEvent func()) FileWatcher {
+	return DummyFileWatcher{}
+}
+
+// Close ends the watch
+func (f DummyFileWatcher) Close() error {
+	return nil
+}

internal/watch/file_watcher.go

@@ -24,8 +24,12 @@ import (
 	"gopkg.in/fsnotify.v1"
 )
 
-// FileWatcher defines a watch over a file
-type FileWatcher struct {
+type FileWatcher interface {
+	Close() error
+}
+
+// OSFileWatcher defines a watch over a file
+type OSFileWatcher struct {
 	file    string
 	watcher *fsnotify.Watcher
 	// onEvent callback to be invoked after the file being watched changes
@@ -34,7 +38,7 @@ type FileWatcher struct {
 
 // NewFileWatcher creates a new FileWatcher
 func NewFileWatcher(file string, onEvent func()) (FileWatcher, error) {
-	fw := FileWatcher{
+	fw := OSFileWatcher{
 		file:    file,
 		onEvent: onEvent,
 	}
@@ -43,12 +47,12 @@ func NewFileWatcher(file string, onEvent func()) (FileWatcher, error) {
 }
 
 // Close ends the watch
-func (f *FileWatcher) Close() error {
+func (f OSFileWatcher) Close() error {
 	return f.watcher.Close()
 }
 
 // watch creates a fsnotify watcher for a file and create of write events
-func (f *FileWatcher) watch() error {
+func (f *OSFileWatcher) watch() error {
 	watcher, err := fsnotify.NewWatcher()
 	if err != nil {
 		return err