Add e2e tests

vendor/cloud.google.com/go/license_test.go

@@ -0,0 +1,70 @@
+// Copyright 2016 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 cloud
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+var sentinels = []string{
+	"Copyright",
+	"Google Inc",
+	`Licensed under the Apache License, Version 2.0 (the "License");`,
+}
+
+func TestLicense(t *testing.T) {
+	err := filepath.Walk(".", func(path string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if ext := filepath.Ext(path); ext != ".go" && ext != ".proto" {
+			return nil
+		}
+		if strings.HasSuffix(path, ".pb.go") {
+			// .pb.go files are generated from the proto files.
+			// .proto files must have license headers.
+			return nil
+		}
+		if path == "bigtable/cmd/cbt/cbtdoc.go" {
+			// Automatically generated.
+			return nil
+		}
+
+		src, err := ioutil.ReadFile(path)
+		if err != nil {
+			return nil
+		}
+		src = src[:140] // Ensure all of the sentinel values are at the top of the file.
+
+		// Find license
+		for _, sentinel := range sentinels {
+			if !bytes.Contains(src, []byte(sentinel)) {
+				t.Errorf("%v: license header not present. want %q", path, sentinel)
+				return nil
+			}
+		}
+
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+}