Copyright 2019 The Chromium OS Authors. All rights reserved. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
AssertContentsEqual checks that there's no difference between two directories/files.
AssertGitBranches asserts that the git repo has the given branches (it may have others, too).
AssertGitBranches asserts that the git repo has only the correct branches.