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

internal/file/filesystem_test.go

@@ -0,0 +1,37 @@
+/*
+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 file
+
+import (
+	"testing"
+)
+
+func TestNewFakeFS(t *testing.T) {
+	fs, err := NewFakeFS()
+	if err != nil {
+		t.Fatalf("unexpected error creating filesystem abstraction: %v", err)
+	}
+
+	if fs == nil {
+		t.Fatal("expected a filesystem but none returned")
+	}
+
+	_, err = fs.Stat("/etc/nginx/nginx.conf")
+	if err != nil {
+		t.Fatalf("unexpected error reading default nginx.conf file: %v", err)
+	}
+}