Vendor dependencies for GCS

vendor/cloud.google.com/go/internal/pretty/diff.go

@@ -0,0 +1,78 @@
+// 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 pretty
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"syscall"
+)
+
+// Diff compares the pretty-printed representation of two values. The second
+// return value reports whether the two values' representations are identical.
+// If it is false, the first return value contains the diffs.
+//
+// The output labels the first value "want" and the second "got".
+//
+// Diff works by invoking the "diff" command. It will only succeed in
+// environments where "diff" is on the shell path.
+func Diff(want, got interface{}) (string, bool, error) {
+	fname1, err := writeToTemp(want)
+	if err != nil {
+		return "", false, err
+	}
+	defer os.Remove(fname1)
+
+	fname2, err := writeToTemp(got)
+	if err != nil {
+		return "", false, err
+	}
+	defer os.Remove(fname2)
+
+	cmd := exec.Command("diff", "-u", "--label=want", "--label=got", fname1, fname2)
+	out, err := cmd.Output()
+	if err == nil {
+		return string(out), true, nil
+	}
+	eerr, ok := err.(*exec.ExitError)
+	if !ok {
+		return "", false, err
+	}
+	ws, ok := eerr.Sys().(syscall.WaitStatus)
+	if !ok {
+		return "", false, err
+	}
+	if ws.ExitStatus() != 1 {
+		return "", false, err
+	}
+	// Exit status of 1 means no error, but diffs were found.
+	return string(out), false, nil
+}
+
+func writeToTemp(v interface{}) (string, error) {
+	f, err := ioutil.TempFile("", "prettyDiff")
+	if err != nil {
+		return "", err
+	}
+	if _, err := fmt.Fprintf(f, "%+v\n", Value(v)); err != nil {
+		return "", err
+	}
+	if err := f.Close(); err != nil {
+		return "", err
+	}
+	return f.Name(), nil
+}