depot_tools/testing_support/fake_repos.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2011 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.

"""Generate fake repositories for testing."""

from __future__ import print_function

import atexit
import datetime
import errno
import logging
import os
import pprint
import random
import re
import socket
import sys
import tempfile
import textwrap
import time

# trial_dir must be first for non-system libraries.
from testing_support import trial_dir
import gclient_utils
import scm
import subprocess2


# Attempt |MAX_TRY| times to find a free port. Each time select one port at
# random from the range [|PORT_START|, |PORT_END|].
MAX_TRY = 10
PORT_START = 20000
PORT_END = 65535


def write(path, content):
  f = open(path, 'wb')
  f.write(content.encode())
  f.close()


join = os.path.join


def read_tree(tree_root):
  """Returns a dict of all the files in a tree. Defaults to self.root_dir."""
  tree = {}
  for root, dirs, files in os.walk(tree_root):
    for d in filter(lambda x: x.startswith('.'), dirs):
      dirs.remove(d)
    for f in [join(root, f) for f in files if not f.startswith('.')]:
      filepath = f[len(tree_root) + 1:].replace(os.sep, '/')
      assert len(filepath), f
      tree[filepath] = gclient_utils.FileRead(join(root, f))
  return tree


def dict_diff(dict1, dict2):
  diff = {}
  for k, v in dict1.items():
    if k not in dict2:
      diff[k] = v
    elif v != dict2[k]:
      diff[k] = (v, dict2[k])
  for k, v in dict2.items():
    if k not in dict1:
      diff[k] = v
  return diff


def commit_git(repo):
  """Commits the changes and returns the new hash."""
  subprocess2.check_call(['git', 'add', '-A', '-f'], cwd=repo)
  subprocess2.check_call(['git', 'commit', '-q', '--message', 'foo'], cwd=repo)
  rev = subprocess2.check_output(
      ['git', 'show-ref', '--head', 'HEAD'], cwd=repo).split(b' ', 1)[0]
  rev = rev.decode('utf-8')
  logging.debug('At revision %s' % rev)
  return rev


def port_is_free(host, port):
  s = socket.socket()
  try:
    return s.connect_ex((host, port)) != 0
  finally:
    s.close()


def find_free_port(host):
  """Finds a listening port free to listen to."""
  for _ in range(MAX_TRY):
    base_port = random.randint(PORT_START, PORT_END)
    if port_is_free(host, base_port):
      return base_port
  assert False, 'Having issues finding an available port'


def wait_for_port_to_bind(host, port, process):
  try:
    start = datetime.datetime.utcnow()
    maxdelay = datetime.timedelta(seconds=30)
    while (datetime.datetime.utcnow() - start) < maxdelay:
      sock = socket.socket()
      try:
        sock.connect((host, port))
        logging.debug('%d is now bound' % port)
        return
      except (socket.error, EnvironmentError):
        # Sleep a little bit to avoid spinning too much.
        time.sleep(0.2)
      logging.debug('%d is still not bound' % port)
  finally:
    sock.close()
  # The process failed to bind. Kill it and dump its ouput.
  process.kill()
  stdout, stderr = process.communicate()
  logging.debug('%s' % stdout)
  logging.error('%s' % stderr)
  assert False, '%d is still not bound' % port


def wait_for_port_to_free(host, port):
  start = datetime.datetime.utcnow()
  maxdelay = datetime.timedelta(seconds=30)
  while (datetime.datetime.utcnow() - start) < maxdelay:
    try:
      sock = socket.socket()
      sock.connect((host, port))
      logging.debug('%d was bound, waiting to free' % port)
    except (socket.error, EnvironmentError):
      logging.debug('%d now free' % port)
      return
    finally:
      sock.close()
  assert False, '%d is still bound' % port


class FakeReposBase(object):
  """Generate git repositories to test gclient functionality.

  Many DEPS functionalities need to be tested: Var, deps_os, hooks,
  use_relative_paths.

  And types of dependencies: Relative urls, Full urls, git.

  populateGit() needs to be implemented by the subclass.
  """
  # Hostname
  NB_GIT_REPOS = 1
  USERS = [
      ('user1@example.com', 'foo Fuß'),
      ('user2@example.com', 'bar'),
  ]

  def __init__(self, host=None):
    self.trial = trial_dir.TrialDir('repos')
    self.host = host or '127.0.0.1'
    # Format is { repo: [ None, (hash, tree), (hash, tree), ... ], ... }
    # so reference looks like self.git_hashes[repo][rev][0] for hash and
    # self.git_hashes[repo][rev][1] for it's tree snapshot.
    # It is 1-based too.
    self.git_hashes = {}
    self.gitdaemon = None
    self.git_pid_file_name = None
    self.git_root = None
    self.git_dirty = False
    self.git_port = None
    self.git_base = None

  @property
  def root_dir(self):
    return self.trial.root_dir

  def set_up(self):
    """All late initialization comes here."""
    self.cleanup_dirt()
    if not self.root_dir:
      try:
        # self.root_dir is not set before this call.
        self.trial.set_up()
        self.git_root = join(self.root_dir, 'git')
      finally:
        # Registers cleanup.
        atexit.register(self.tear_down)

  def cleanup_dirt(self):
    """For each dirty repository, destroy it."""
    if self.git_dirty:
      if not self.tear_down_git():
        logging.error('Using both leaking checkout and git dirty checkout')

  def tear_down(self):
    """Kills the servers and delete the directories."""
    self.tear_down_git()
    # This deletes the directories.
    self.trial.tear_down()
    self.trial = None

  def tear_down_git(self):
    if self.gitdaemon:
      logging.debug('Killing git-daemon pid %s' % self.gitdaemon.pid)
      self.gitdaemon.kill()
      self.gitdaemon = None
      if self.git_pid_file_name:
        pid = int(open(self.git_pid_file_name).read())
        logging.debug('Killing git daemon pid %s' % pid)
        try:
          subprocess2.kill_pid(pid)
        except OSError as e:
          if e.errno != errno.ESRCH:  # no such process
            raise
        os.remove(self.git_pid_file_name)
        self.git_pid_file_name = None
      wait_for_port_to_free(self.host, self.git_port)
      self.git_port = None
      self.git_base = None
      if not self.trial.SHOULD_LEAK:
        logging.debug('Removing %s' % self.git_root)
        gclient_utils.rmtree(self.git_root)
      else:
        return False
    return True

  @staticmethod
  def _genTree(root, tree_dict):
    """For a dictionary of file contents, generate a filesystem."""
    if not os.path.isdir(root):
      os.makedirs(root)
    for (k, v) in tree_dict.items():
      k_os = k.replace('/', os.sep)
      k_arr = k_os.split(os.sep)
      if len(k_arr) > 1:
        p = os.sep.join([root] + k_arr[:-1])
        if not os.path.isdir(p):
          os.makedirs(p)
      if v is None:
        os.remove(join(root, k))
      else:
        write(join(root, k), v)

  def set_up_git(self):
    """Creates git repositories and start the servers."""
    self.set_up()
    if self.gitdaemon:
      return True
    assert self.git_pid_file_name == None, self.git_pid_file_name
    try:
      subprocess2.check_output(['git', '--version'])
    except (OSError, subprocess2.CalledProcessError):
      return False
    for repo in ['repo_%d' % r for r in range(1, self.NB_GIT_REPOS + 1)]:
      subprocess2.check_call(['git', 'init', '-q', join(self.git_root, repo)])
      self.git_hashes[repo] = [(None, None)]
    git_pid_file = tempfile.NamedTemporaryFile(delete=False)
    self.git_pid_file_name = git_pid_file.name
    git_pid_file.close()
    self.git_port = find_free_port(self.host)
    self.git_base = 'git://%s:%d/git/' % (self.host, self.git_port)
    cmd = ['git', 'daemon',
        '--export-all',
        '--reuseaddr',
        '--base-path=' + self.root_dir,
        '--pid-file=' + self.git_pid_file_name,
        '--port=%d' % self.git_port]
    if self.host == '127.0.0.1':
      cmd.append('--listen=' + self.host)
    # Verify that the port is free.
    if not port_is_free(self.host, self.git_port):
      return False
    # Start the daemon.
    self.gitdaemon = subprocess2.Popen(
        cmd,
        cwd=self.root_dir,
        stdout=subprocess2.PIPE,
        stderr=subprocess2.PIPE)
    wait_for_port_to_bind(self.host, self.git_port, self.gitdaemon)
    self.populateGit()
    self.git_dirty = False
    return True

  def _git_rev_parse(self, path):
    return subprocess2.check_output(
        ['git', 'rev-parse', 'HEAD'], cwd=path).strip()

  def _commit_git(self, repo, tree, base=None):
    repo_root = join(self.git_root, repo)
    if base:
      base_commit = self.git_hashes[repo][base][0]
      subprocess2.check_call(
          ['git', 'checkout', base_commit], cwd=repo_root)
    self._genTree(repo_root, tree)
    commit_hash = commit_git(repo_root)
    base = base or -1
    if self.git_hashes[repo][base][1]:
      new_tree = self.git_hashes[repo][base][1].copy()
      new_tree.update(tree)
    else:
      new_tree = tree.copy()
    self.git_hashes[repo].append((commit_hash, new_tree))

  def _create_ref(self, repo, ref, revision):
    repo_root = join(self.git_root, repo)
    subprocess2.check_call(
        ['git', 'update-ref', ref, self.git_hashes[repo][revision][0]],
        cwd=repo_root)

  def _fast_import_git(self, repo, data):
    repo_root = join(self.git_root, repo)
    logging.debug('%s: fast-import %s', repo, data)
    subprocess2.check_call(
        ['git', 'fast-import', '--quiet'], cwd=repo_root, stdin=data.encode())

  def populateGit(self):
    raise NotImplementedError()


class FakeRepos(FakeReposBase):
  """Implements populateGit()."""
  NB_GIT_REPOS = 16

  def populateGit(self):
    # Testing:
    # - dependency disappear
    # - dependency renamed
    # - versioned and unversioned reference
    # - relative and full reference
    # - deps_os
    # - var
    # - hooks
    # TODO(maruel):
    # - use_relative_paths
    self._commit_git('repo_3', {
      'origin': 'git/repo_3@1\n',
    })

    self._commit_git('repo_3', {
      'origin': 'git/repo_3@2\n',
    })

    self._commit_git('repo_1', {
      'DEPS': """
vars = {
  'DummyVariable': 'repo',
  'false_var': False,
  'false_str_var': 'False',
  'true_var': True,
  'true_str_var': 'True',
  'str_var': 'abc',
  'cond_var': 'false_str_var and true_var',
}
# Nest the args file in a sub-repo, to make sure we don't try to
# write it before we've cloned everything.
gclient_gn_args_file = 'src/repo2/gclient.args'
gclient_gn_args = [
  'false_var',
  'false_str_var',
  'true_var',
  'true_str_var',
  'str_var',
  'cond_var',
]
deps = {
  'src/repo2': {
    'url': '%(git_base)srepo_2',
    'condition': 'True',
  },
  'src/repo2/repo3': '/' + Var('DummyVariable') + '_3@%(hash3)s',
  # Test that deps where condition evaluates to False are skipped.
  'src/repo5': {
    'url': '/repo_5',
    'condition': 'False',
  },
}
deps_os = {
  'mac': {
    'src/repo4': '/repo_4',
  },
}""" % {
            'git_base': self.git_base,
            # See self.__init__() for the format. Grab's the hash of the first
            # commit in repo_2. Only keep the first 7 character because of:
            # TODO(maruel): http://crosbug.com/3591 We need to strip the hash..
            # duh.
            'hash3': self.git_hashes['repo_3'][1][0][:7]
        },
        'origin': 'git/repo_1@1\n',
    })

    self._commit_git('repo_2', {
      'origin': 'git/repo_2@1\n',
      'DEPS': """
vars = {
  'repo2_false_var': 'False',
}

deps = {
  'foo/bar': {
    'url': '/repo_3',
    'condition': 'repo2_false_var',
  }
}
""",
    })

    self._commit_git('repo_2', {
      'origin': 'git/repo_2@2\n',
    })

    self._commit_git('repo_4', {
      'origin': 'git/repo_4@1\n',
    })

    self._commit_git('repo_4', {
      'origin': 'git/repo_4@2\n',
    })

    self._commit_git('repo_1', {
      'DEPS': """
deps = {
  'src/repo2': '%(git_base)srepo_2@%(hash)s',
  'src/repo2/repo_renamed': '/repo_3',
  'src/should_not_process': {
    'url': '/repo_4',
    'condition': 'False',
  }
}
# I think this is wrong to have the hooks run from the base of the gclient
# checkout. It's maybe a bit too late to change that behavior.
hooks = [
  {
    'pattern': '.',
    'action': ['python', '-c',
               'open(\\'src/git_hooked1\\', \\'w\\').write(\\'git_hooked1\\')'],
  },
  {
    # Should not be run.
    'pattern': 'nonexistent',
    'action': ['python', '-c',
               'open(\\'src/git_hooked2\\', \\'w\\').write(\\'git_hooked2\\')'],
  },
]
""" % {
        'git_base': self.git_base,
        # See self.__init__() for the format. Grab's the hash of the first
        # commit in repo_2. Only keep the first 7 character because of:
        # TODO(maruel): http://crosbug.com/3591 We need to strip the hash.. duh.
        'hash': self.git_hashes['repo_2'][1][0][:7]
      },
      'origin': 'git/repo_1@2\n',
    })

    self._commit_git('repo_5', {'origin': 'git/repo_5@1\n'})
    self._commit_git('repo_5', {
      'DEPS': """
deps = {
  'src/repo1': '%(git_base)srepo_1@%(hash1)s',
  'src/repo2': '%(git_base)srepo_2@%(hash2)s',
}

# Hooks to run after a project is processed but before its dependencies are
# processed.
pre_deps_hooks = [
  {
    'action': ['python', '-c',
               'print("pre-deps hook"); open(\\'src/git_pre_deps_hooked\\', \\'w\\').write(\\'git_pre_deps_hooked\\')'],
  }
]
""" % {
         'git_base': self.git_base,
         'hash1': self.git_hashes['repo_1'][2][0][:7],
         'hash2': self.git_hashes['repo_2'][1][0][:7],
      },
    'origin': 'git/repo_5@2\n',
    })
    self._commit_git('repo_5', {
      'DEPS': """
deps = {
  'src/repo1': '%(git_base)srepo_1@%(hash1)s',
  'src/repo2': '%(git_base)srepo_2@%(hash2)s',
}

# Hooks to run after a project is processed but before its dependencies are
# processed.
pre_deps_hooks = [
  {
    'action': ['python', '-c',
               'print("pre-deps hook"); open(\\'src/git_pre_deps_hooked\\', \\'w\\').write(\\'git_pre_deps_hooked\\')'],
  },
  {
    'action': ['python', '-c', 'import sys; sys.exit(1)'],
  }
]
""" % {
         'git_base': self.git_base,
         'hash1': self.git_hashes['repo_1'][2][0][:7],
         'hash2': self.git_hashes['repo_2'][1][0][:7],
      },
    'origin': 'git/repo_5@3\n',
    })

    self._commit_git('repo_6', {
      'DEPS': """
vars = {
  'DummyVariable': 'repo',
  'git_base': '%(git_base)s',
  'hook1_contents': 'git_hooked1',
  'repo5_var': '/repo_5',

  'false_var': False,
  'false_str_var': 'False',
  'true_var': True,
  'true_str_var': 'True',
  'str_var': 'abc',
  'cond_var': 'false_str_var and true_var',
}

gclient_gn_args_file = 'src/repo2/gclient.args'
gclient_gn_args = [
  'false_var',
  'false_str_var',
  'true_var',
  'true_str_var',
  'str_var',
  'cond_var',
]

allowed_hosts = [
  '%(git_base)s',
]
deps = {
  'src/repo2': {
    'url': Var('git_base') + 'repo_2@%(hash)s',
    'condition': 'true_str_var',
  },
  'src/repo4': {
    'url': '/repo_4',
    'condition': 'False',
  },
  # Entries can have a None repository, which has the effect of either:
  # - disabling a dep checkout (e.g. in a .gclient solution to prevent checking
  # out optional large repos, or in deps_os where some repos aren't used on some
  # platforms)
  # - allowing a completely local directory to be processed by gclient (handy
  # for dealing with "custom" DEPS, like buildspecs).
  '/repoLocal': {
    'url': None,
  },
  'src/repo8': '/repo_8',
  'src/repo15': '/repo_15',
  'src/repo16': '/repo_16',
}
deps_os ={
  'mac': {
    # This entry should not appear in flattened DEPS' |deps|.
    'src/mac_repo': '{repo5_var}',
  },
  'unix': {
    # This entry should not appear in flattened DEPS' |deps|.
    'src/unix_repo': '{repo5_var}',
  },
  'win': {
    # This entry should not appear in flattened DEPS' |deps|.
    'src/win_repo': '{repo5_var}',
  },
}
hooks = [
  {
    'pattern': '.',
    'condition': 'True',
    'action': ['python', '-c',
               'open(\\'src/git_hooked1\\', \\'w\\').write(\\'{hook1_contents}\\')'],
  },
  {
    # Should not be run.
    'pattern': 'nonexistent',
    'action': ['python', '-c',
               'open(\\'src/git_hooked2\\', \\'w\\').write(\\'git_hooked2\\')'],
  },
]
hooks_os = {
  'mac': [
    {
      'pattern': '.',
      'action': ['python', '-c',
                 'open(\\'src/git_hooked_mac\\', \\'w\\').write('
                     '\\'git_hooked_mac\\')'],
    },
  ],
}
recursedeps = [
  'src/repo2',
  'src/repo8',
  'src/repo15',
  'src/repo16',
]""" % {
        'git_base': self.git_base,
        'hash': self.git_hashes['repo_2'][1][0][:7]
      },
      'origin': 'git/repo_6@1\n',
    })

    self._commit_git('repo_7', {
      'DEPS': """
vars = {
  'true_var': 'True',
  'false_var': 'true_var and False',
}
hooks = [
  {
    'action': ['python', '-c',
               'open(\\'src/should_run\\', \\'w\\').write(\\'should_run\\')'],
    'condition': 'true_var or True',
  },
  {
    'action': ['python', '-c',
               'open(\\'src/should_not_run\\', \\'w\\').write(\\'should_not_run\\')'],
    'condition': 'false_var',
  },
]""",
      'origin': 'git/repo_7@1\n',
    })

    self._commit_git('repo_8', {
      'DEPS': """
deps_os ={
  'mac': {
    'src/recursed_os_repo': '/repo_5',
  },
  'unix': {
    'src/recursed_os_repo': '/repo_5',
  },
}""",
      'origin': 'git/repo_8@1\n',
    })

    self._commit_git('repo_9', {
      'DEPS': """
vars = {
  'str_var': 'xyz',
}
gclient_gn_args_file = 'src/repo2/gclient.args'
gclient_gn_args = [
  'str_var',
]
deps = {
  'src/repo8': '/repo_8',

  # This entry should appear in flattened file,
  # but not recursed into, since it's not
  # in recursedeps.
  'src/repo7': '/repo_7',
}
deps_os = {
  'android': {
    # This entry should only appear in flattened |deps_os|,
    # not |deps|, even when used with |recursedeps|.
    'src/repo4': '/repo_4',
  }
}
recursedeps = [
  'src/repo4',
  'src/repo8',
]""",
      'origin': 'git/repo_9@1\n',
    })

    self._commit_git('repo_10', {
      'DEPS': """
gclient_gn_args_from = 'src/repo9'
deps = {
  'src/repo9': '/repo_9',

  # This entry should appear in flattened file,
  # but not recursed into, since it's not
  # in recursedeps.
  'src/repo6': '/repo_6',
}
deps_os = {
  'mac': {
    'src/repo11': '/repo_11',
  },
  'ios': {
    'src/repo11': '/repo_11',
  }
}
recursedeps = [
  'src/repo9',
  'src/repo11',
]""",
      'origin': 'git/repo_10@1\n',
    })

    self._commit_git('repo_11', {
      'DEPS': """
deps = {
  'src/repo12': '/repo_12',
}""",
      'origin': 'git/repo_11@1\n',
    })

    self._commit_git('repo_12', {
      'origin': 'git/repo_12@1\n',
    })

    self._fast_import_git('repo_12', """blob
mark :1
data 6
Hello

blob
mark :2
data 4
Bye

reset refs/changes/1212
commit refs/changes/1212
mark :3
author Bob <bob@example.com> 1253744361 -0700
committer Bob <bob@example.com> 1253744361 -0700
data 8
A and B
M 100644 :1 a
M 100644 :2 b
""")

    self._commit_git('repo_13', {
      'DEPS': """
deps = {
  'src/repo12': '/repo_12',
}""",
      'origin': 'git/repo_13@1\n',
    })

    self._commit_git('repo_13', {
      'DEPS': """
deps = {
  'src/repo12': '/repo_12@refs/changes/1212',
}""",
      'origin': 'git/repo_13@2\n',
    })

    # src/repo12 is now a CIPD dependency.
    self._commit_git('repo_13', {
      'DEPS': """
deps = {
  'src/repo12': {
    'packages': [
      {
        'package': 'foo',
        'version': '1.3',
      },
    ],
    'dep_type': 'cipd',
  },
}
hooks = [{
  # make sure src/repo12 exists and is a CIPD dir.
  'action': ['python', '-c', 'with open("src/repo12/_cipd"): pass'],
}]
""",
      'origin': 'git/repo_13@3\n'
    })

    self._commit_git('repo_14', {
      'DEPS': textwrap.dedent("""\
        vars = {}
        deps = {
          'src/cipd_dep': {
            'packages': [
              {
                'package': 'package0',
                'version': '0.1',
              },
            ],
            'dep_type': 'cipd',
          },
          'src/another_cipd_dep': {
            'packages': [
              {
                'package': 'package1',
                'version': '1.1-cr0',
              },
              {
                'package': 'package2',
                'version': '1.13',
              },
            ],
            'dep_type': 'cipd',
          },
          'src/cipd_dep_with_cipd_variable': {
            'packages': [
              {
                'package': 'package3/${{platform}}',
                'version': '1.2',
              },
            ],
            'dep_type': 'cipd',
          },
        }"""),
      'origin': 'git/repo_14@2\n'
    })

    # A repo with a hook to be recursed in, without use_relative_hooks
    self._commit_git('repo_15', {
      'DEPS': textwrap.dedent("""\
        hooks = [{
          "name": "absolute_cwd",
          "pattern": ".",
          "action": ["python", "-c", "pass"]
        }]"""),
      'origin': 'git/repo_15@2\n'
    })
    # A repo with a hook to be recursed in, with use_relative_hooks
    self._commit_git('repo_16', {
      'DEPS': textwrap.dedent("""\
        use_relative_paths=True
        use_relative_hooks=True
        hooks = [{
          "name": "relative_cwd",
          "pattern": ".",
          "action": ["python", "relative.py"]
        }]"""),
      'relative.py': 'pass',
      'origin': 'git/repo_16@2\n'
    })

class FakeRepoSkiaDEPS(FakeReposBase):
  """Simulates the Skia DEPS transition in Chrome."""

  NB_GIT_REPOS = 5

  DEPS_git_pre = """deps = {
  'src/third_party/skia/gyp': '%(git_base)srepo_3',
  'src/third_party/skia/include': '%(git_base)srepo_4',
  'src/third_party/skia/src': '%(git_base)srepo_5',
}"""

  DEPS_post = """deps = {
  'src/third_party/skia': '%(git_base)srepo_1',
}"""

  def populateGit(self):
    # Skia repo.
    self._commit_git('repo_1', {
        'skia_base_file': 'root-level file.',
        'gyp/gyp_file': 'file in the gyp directory',
        'include/include_file': 'file in the include directory',
        'src/src_file': 'file in the src directory',
    })
    self._commit_git('repo_3', { # skia/gyp
        'gyp_file': 'file in the gyp directory',
    })
    self._commit_git('repo_4', { # skia/include
        'include_file': 'file in the include directory',
    })
    self._commit_git('repo_5', { # skia/src
        'src_file': 'file in the src directory',
    })

    # Chrome repo.
    self._commit_git('repo_2', {
        'DEPS': self.DEPS_git_pre % {'git_base': self.git_base},
        'myfile': 'src/trunk/src@1'
    })
    self._commit_git('repo_2', {
        'DEPS': self.DEPS_post % {'git_base': self.git_base},
        'myfile': 'src/trunk/src@2'
    })


class FakeRepoBlinkDEPS(FakeReposBase):
  """Simulates the Blink DEPS transition in Chrome."""

  NB_GIT_REPOS = 2
  DEPS_pre = 'deps = {"src/third_party/WebKit": "%(git_base)srepo_2",}'
  DEPS_post = 'deps = {}'

  def populateGit(self):
    # Blink repo.
    self._commit_git('repo_2', {
        'OWNERS': 'OWNERS-pre',
        'Source/exists_always': '_ignored_',
        'Source/exists_before_but_not_after': '_ignored_',
    })

    # Chrome repo.
    self._commit_git('repo_1', {
        'DEPS': self.DEPS_pre % {'git_base': self.git_base},
        'myfile': 'myfile@1',
        '.gitignore': '/third_party/WebKit',
    })
    self._commit_git('repo_1', {
        'DEPS': self.DEPS_post % {'git_base': self.git_base},
        'myfile': 'myfile@2',
        '.gitignore': '',
        'third_party/WebKit/OWNERS': 'OWNERS-post',
        'third_party/WebKit/Source/exists_always': '_ignored_',
        'third_party/WebKit/Source/exists_after_but_not_before': '_ignored',
    })

  def populateSvn(self):
    raise NotImplementedError()


class FakeReposTestBase(trial_dir.TestCase):
  """This is vaguely inspired by twisted."""
  # Static FakeRepos instances. Lazy loaded.
  CACHED_FAKE_REPOS = {}
  # Override if necessary.
  FAKE_REPOS_CLASS = FakeRepos

  def setUp(self):
    super(FakeReposTestBase, self).setUp()
    if not self.FAKE_REPOS_CLASS in self.CACHED_FAKE_REPOS:
      self.CACHED_FAKE_REPOS[self.FAKE_REPOS_CLASS] = self.FAKE_REPOS_CLASS()
    self.FAKE_REPOS = self.CACHED_FAKE_REPOS[self.FAKE_REPOS_CLASS]
    # No need to call self.FAKE_REPOS.setUp(), it will be called by the child
    # class.
    # Do not define tearDown(), since super's version does the right thing and
    # self.FAKE_REPOS is kept across tests.

  @property
  def git_base(self):
    """Shortcut."""
    return self.FAKE_REPOS.git_base

  def checkString(self, expected, result, msg=None):
    """Prints the diffs to ease debugging."""
    self.assertEqual(expected.splitlines(), result.splitlines(), msg)
    if expected != result:
      # Strip the begining
      while expected and result and expected[0] == result[0]:
        expected = expected[1:]
        result = result[1:]
      # The exception trace makes it hard to read so dump it too.
      if '\n' in result:
        print(result)
    self.assertEqual(expected, result, msg)

  def check(self, expected, results):
    """Checks stdout, stderr, returncode."""
    self.checkString(expected[0], results[0])
    self.checkString(expected[1], results[1])
    self.assertEqual(expected[2], results[2])

  def assertTree(self, tree, tree_root=None):
    """Diff the checkout tree with a dict."""
    if not tree_root:
      tree_root = self.root_dir
    actual = read_tree(tree_root)
    diff = dict_diff(tree, actual)
    if diff:
      logging.error('Actual %s\n%s' % (tree_root, pprint.pformat(actual)))
      logging.error('Expected\n%s' % pprint.pformat(tree))
      logging.error('Diff\n%s' % pprint.pformat(diff))
    self.assertEqual(diff, {})

  def mangle_git_tree(self, *args):
    """Creates a 'virtual directory snapshot' to compare with the actual result
    on disk."""
    result = {}
    for item, new_root in args:
      repo, rev = item.split('@', 1)
      tree = self.gittree(repo, rev)
      for k, v in tree.items():
        result[join(new_root, k)] = v
    return result

  def githash(self, repo, rev):
    """Sort-hand: Returns the hash for a git 'revision'."""
    return self.FAKE_REPOS.git_hashes[repo][int(rev)][0]

  def gittree(self, repo, rev):
    """Sort-hand: returns the directory tree for a git 'revision'."""
    return self.FAKE_REPOS.git_hashes[repo][int(rev)][1]

  def gitrevparse(self, repo):
    """Returns the actual revision for a given repo."""
    return self.FAKE_REPOS._git_rev_parse(repo).decode('utf-8')


def main(argv):
  fake = FakeRepos()
  print('Using %s' % fake.root_dir)
  try:
    fake.set_up_git()
    print('Fake setup, press enter to quit or Ctrl-C to keep the checkouts.')
    sys.stdin.readline()
  except KeyboardInterrupt:
    trial_dir.TrialDir.SHOULD_LEAK.leak = True
  return 0


if __name__ == '__main__':
  sys.exit(main(sys.argv))