mockfs

utils/fs/fs.go

@@ -0,0 +1,44 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// 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 fs
+
+import (
+	"io"
+	"os"
+)
+
+type osFS struct{}
+
+func (osFS) Open(name string) (File, error)        { return os.Open(name) }
+func (osFS) Stat(name string) (os.FileInfo, error) { return os.Stat(name) }
+
+var fs FileSystem = osFS{}
+
+type FileSystem interface {
+	Open(name string) (File, error)
+}
+
+type File interface {
+	io.ReadWriteCloser
+}
+
+// Useful for tests. Not thread safe.
+func ChangeFileSystem(filesystem FileSystem) {
+	fs = filesystem
+}
+
+func Open(name string) (File, error) {
+	return fs.Open(name)
+}

utils/fs/mockfs/mockfs.go

@@ -0,0 +1,65 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// 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 mockfs
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/google/cadvisor/utils/fs"
+	"github.com/stretchr/testify/mock"
+)
+
+type MockFile struct {
+	mock.Mock
+	bytes.Buffer
+	checkClose bool
+}
+
+func (self *MockFile) CheckClose() *MockFile {
+	self.checkClose = true
+	return self
+}
+
+func (self *MockFile) Close() error {
+	if self.checkClose {
+		args := self.Called()
+		return args.Error(0)
+	}
+	return nil
+}
+
+type MockFileSystem struct {
+	mock.Mock
+	files map[string]*MockFile
+}
+
+func (self *MockFileSystem) AddTextFile(name, content string) *MockFile {
+	if self.files == nil {
+		self.files = make(map[string]*MockFile, 4)
+	}
+	f := &MockFile{
+		Buffer: *bytes.NewBufferString(content),
+	}
+	self.files[name] = f
+	return f
+}
+
+func (self *MockFileSystem) Open(name string) (fs.File, error) {
+	if f, ok := self.files[name]; ok {
+		return f, nil
+	}
+	return nil, fmt.Errorf("cannot open file %v", name)
+}

utils/procfs/schedstats.go

@@ -18,8 +18,9 @@ import (
 	"bufio"
 	"fmt"
 	"io"
-	"os"
 	"strconv"
+
+	"github.com/google/cadvisor/utils/fs"
 )
 
 type ProcessSchedStat struct {
@@ -66,7 +67,7 @@ func (self *ProcessSchedStat) Add(pid int) error {
 	}
 
 	path := fmt.Sprintf("/proc/%d/schedstat", pid)
-	f, err := os.Open(path)
+	f, err := fs.Open(path)
 	if err != nil {
 		return err
 	}

utils/procfs/schedstats_test.go

@@ -0,0 +1,52 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// 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 procfs
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"github.com/google/cadvisor/utils/fs"
+	"github.com/google/cadvisor/utils/fs/mockfs"
+)
+
+func TestReadProcessSchedStat(t *testing.T) {
+
+	mockfs := &mockfs.MockFileSystem{}
+
+	pid := 10
+
+	stat := &ProcessSchedStat{
+		NumProcesses:  1,
+		Running:       100,
+		RunWait:       120,
+		NumTimeSlices: 130,
+	}
+
+	path := fmt.Sprintf("/proc/%v/schedstat", pid)
+	content := fmt.Sprintf("%v %v %v\n", stat.Running, stat.RunWait, stat.NumTimeSlices)
+	mockfs.AddTextFile(path, content)
+	fs.ChangeFileSystem(mockfs)
+
+	receivedStat := &ProcessSchedStat{}
+	err := receivedStat.Add(pid)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(receivedStat, stat) {
+		t.Errorf("Received wrong schedstat: %+v", receivedStat)
+	}
+}