change: import Change type from docker

Related to #65.

change.go

@@ -0,0 +1,33 @@
+// Copyright 2014 go-dockerclient 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 docker
+
+import "fmt"
+
+type ChangeType int
+
+const (
+	ChangeModify ChangeType = iota
+	ChangeAdd
+	ChangeDelete
+)
+
+type Change struct {
+	Path string
+	Kind ChangeType
+}
+
+func (change *Change) String() string {
+	var kind string
+	switch change.Kind {
+	case ChangeModify:
+		kind = "C"
+	case ChangeAdd:
+		kind = "A"
+	case ChangeDelete:
+		kind = "D"
+	}
+	return fmt.Sprintf("%s %s", kind, change.Path)
+}

change_test.go

@@ -0,0 +1,26 @@
+// Copyright 2014 go-dockerclient 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 docker
+
+import (
+	"testing"
+)
+
+func TestChangeString(t *testing.T) {
+	var tests = []struct {
+		change   Change
+		expected string
+	}{
+		{Change{"/etc/passwd", ChangeModify}, "C /etc/passwd"},
+		{Change{"/etc/passwd", ChangeAdd}, "A /etc/passwd"},
+		{Change{"/etc/passwd", ChangeDelete}, "D /etc/passwd"},
+		{Change{"/etc/passwd", 33}, " /etc/passwd"},
+	}
+	for _, tt := range tests {
+		if got := tt.change.String(); got != tt.expected {
+			t.Errorf("Change.String(): want %q. Got %q.", tt.expected, got)
+		}
+	}
+}