cipd: Refactor client to make it more readable.

go/src/infra/tools/cipd/local/testing.go

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package local
+
+import (
+        "bytes"
+        "fmt"
+        "io"
+        "io/ioutil"
+)
+
+// NewTestFile returns File implementation (Symlink == false) backed by a fake
+// in-memory data. It is useful in unit tests.
+func NewTestFile(name string, data string, executable bool) File {
+        return &testFile{
+                name:       name,
+                data:       data,
+                executable: executable,
+        }
+}
+
+// NewTestSymlink returns File implementation (Symlink == true) backed by a fake
+// in-memory data. It is useful in unit tests.
+func NewTestSymlink(name string, target string) File {
+        return &testFile{
+                name:          name,
+                symlinkTarget: target,
+        }
+}
+
+type testFile struct {
+        name          string
+        data          string
+        executable    bool
+        symlinkTarget string
+}
+
+func (f *testFile) Name() string     { return f.name }
+func (f *testFile) Size() uint64     { return uint64(len(f.data)) }
+func (f *testFile) Executable() bool { return f.executable }
+func (f *testFile) Symlink() bool    { return f.symlinkTarget != "" }
+
+func (f *testFile) SymlinkTarget() (string, error) {
+        if f.symlinkTarget == "" {
+                return "", fmt.Errorf("Not a symlink: %s", f.Name())
+        }
+        return f.symlinkTarget, nil
+}
+
+func (f *testFile) Open() (io.ReadCloser, error) {
+        if f.Symlink() {
+                return nil, fmt.Errorf("Can't open symlink: %s", f.Name())
+        }
+        r := bytes.NewReader([]byte(f.data))
+        return ioutil.NopCloser(r), nil
+}