fixtures-git/fixtures_git/gitfixture.py

287 lines
11 KiB
Python

# Copyright (c) 2013-2016 Hewlett-Packard Development Company, L.P.
# Copyright (c) 2018 Hewlett Packard Enterprise Development Company LP
#
# 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.
import faker
import os
import shutil
import tempfile
import fixtures
import git
from fixtures_git import utils
class GitTree(object):
"""Helper class to build a git repository from a graph definition
Helper class to build a git repository from a graph definition of
nodes and their parent nodes. A list of branches may be provided
where each element has two members corresponding to the name and the
target node it references.
Supports unordered graphs, only requirement is that there is a commit
defined with no parents, which will become the root commit.
Root commits can specified by an empty list as the second member:
('NodeA', [])
Merge commits are specified by multiple nodes:
('NodeMerge', ['Node1', 'Node2'])
An '=' prefix can be used in front of one of the parents of a merge
commit to indicate that the merge commit's tree should be copied
directly from that parent ignoring any contributions from the other
parents' trees (like what git enables with the '-s ours' merge
strategy.
This is used when needing to preserve history but not interested in
the changes from the other branches. One tool that makes extensive
usage of this is _git-upstream.
E.g., the following will result in a merge commit 'C', with parents
'P1' and 'P2', but will have the same tree as 'P1'.
('C', ['=P1', 'P2'])
The tree building code can handle a graph definition being out of
order but will fail to find certain circular dependencies and may
result in an infinite loop.
Examples:
[('A', []), ('B', ['A']), ('C', ['B'])]
[('A', []), ('C', ['B']), ('B', ['A'])]
.. _git-upstream: https://pypi.python.org/pypi/git-upstream
"""
def __init__(self, gitrepo, tree, branches):
self.graph = {}
self.gitrepo = gitrepo
self.repo = gitrepo.repo
self._build_git_tree(tree, branches)
def _commit(self, node):
p_node = utils._get_node_to_pick(node)
if p_node:
self.repo.git.cherry_pick(self.graph[p_node], x=True)
else:
# standard commit
self.gitrepo.add_commits(1, ref="HEAD",
message_prefix="[%s]" % node)
def _merge_commit(self, node, parents):
# merge commits
parent_nodes = [p.lstrip("=") for p in parents]
commits = [str(self.graph[p]) for p in parent_nodes[1:]]
if any([p.startswith("=") for p in parents]):
# special merge commit using inverse of 'ours' by
# emptying the current index and then reading in any
# trees of the nodes prefixed with '='
use = [str(self.graph[p.lstrip("=")])
for p in parents if p.startswith("=")]
try:
self.repo.git.merge(*commits, s="ours", no_commit=True)
except git.exc.GitCommandError as exc:
if 'refusing to merge unrelated histories' in exc.stderr:
self.repo.git.merge(*commits, s="ours", no_commit=True,
allow_unrelated_histories=True)
else:
raise
self.repo.git.read_tree(empty=True)
self.repo.git.read_tree(empty=True)
self.repo.git.read_tree(*use, u=True, reset=True)
elif len(commits) < 2:
# standard merge
try:
self.repo.git.merge(*commits, no_commit=True)
except git.exc.GitCommandError as exc:
if 'refusing to merge unrelated histories' in exc.stderr:
self.repo.git.merge(*commits, no_commit=True,
allow_unrelated_histories=True)
else:
raise
else:
# multi-branch merge, git is not great at handling
# merging multiple orphaned branches
try:
self.repo.git.merge(*commits, s="ours", no_commit=True)
except git.exc.GitCommandError as exc:
if 'refusing to merge unrelated histories' in exc.stderr:
self.repo.git.merge(*commits, s="ours", no_commit=True,
allow_unrelated_histories=True)
else:
raise
self.repo.git.read_tree(empty=True)
self.repo.git.read_tree("HEAD", *commits)
self.repo.git.checkout("--", ".")
self.repo.git.commit(m="[%s] Merging %s into %s" %
(node, ",".join(parent_nodes[1:]),
parent_nodes[0]))
self.repo.git.clean(f=True, d=True, x=True)
def _build_git_tree(self, graph_def, branches=[]):
# require that graphs must have at least 1 node with no
# parents, which is a root commit in git
if not any([True for _, parents in graph_def if not parents]):
assert("No root commit defined in test graph")
for node, parents in utils._reverse_toposort(graph_def):
if not parents:
# root commit
self.repo.git.symbolic_ref("HEAD", "refs/heads/%s" % node)
self.repo.git.rm(".", r=True, cached=True,
with_exceptions=False)
self.repo.git.clean(f=True, d=True, x=True)
self.gitrepo.add_commits(1, ref="HEAD",
message_prefix="[%s]" % node)
# only explicitly listed branches should exist afterwards
self.repo.git.checkout(self.repo.commit())
self.repo.git.branch(node, D=True)
else:
# checkout the dependent node
self.repo.git.checkout(self.graph[parents[0].lstrip('=')])
if len(parents) > 1:
# merge commits
self._merge_commit(node, parents)
else:
self._commit(node)
self.graph[node] = self.repo.commit()
for name, node in branches:
self.repo.git.branch(name, str(self.graph[node]), f=True)
# return to master
self.repo.git.checkout("master")
def commits_from_nodes(self, nodes=[]):
return [self.graph[n] for n in nodes]
class GitFixture(fixtures.Fixture):
"""Create a git repo in which to operate.
By default creates an empty git repository under a temporary
directory and deletes it after use.
It accepts options to automatically define a git repository
layout based on list of commits setting the given branches to
the relevant node once built.
:ivar graph: Iterable describing the tree of git commits to create.
:ivar branches: Dict of node to branch names to set once finished.
:ivar path: Custom path to use, otherwise will create a temporary
directory to use and set the 'path' attribute to it.
:ivar user: Dict describing a user to use for commits, defaults
to 'Example User <user@example.com>',
:ivar clean_on_exit: Control whether to delete the tempoary path
once complete, defaults to 'True', but is ignored if 'path'
is provided.
"""
def __init__(self, graph=None, branches=None, path=None, user=None,
clean_on_exit=True):
# set attributes for use
self.path = path
self.gittree = None
self.repo = None
# internal attributes
self._graph = graph or []
self._branches = branches or []
self._user = {
'name': 'Example User',
'email': 'user@example.com',
}
self._user.update(user or {})
self._clean_on_exit = clean_on_exit
# for text generation
self._faker = faker.Faker()
def _setUp(self):
self._file_list = set()
if not self.path:
tempdir = self.useFixture(fixtures.TempDir())
self.path = os.path.join(tempdir.path, 'git')
if self._clean_on_exit is True:
self.addCleanup(shutil.rmtree, tempdir.path)
os.mkdir(self.path)
g = git.Git(self.path)
g.init()
self.repo = git.Repo(self.path)
self.repo.git.config('user.email', self._user['email'])
self.repo.git.config('user.name', self._user['name'])
self.repo.git.commit(m="Initialize empty repo", allow_empty=True)
if self._graph:
self.gittree = GitTree(self, self._graph, self._branches)
def _create_file(self):
contents = "\n\n".join(self._faker.paragraphs(3))
# always want to ensure the files added to the repo are unique no
# matter which branch they are added to, as otherwise there may
# be conflicts caused by replaying local changes and performing
# merges
while True:
tmpfile = tempfile.NamedTemporaryFile(
dir=self.repo.working_dir, delete=False)
if tmpfile.name not in self._file_list:
self._file_list.add(tmpfile.name)
break
# case where same filename in use on a different branch
tmpfile.close()
os.remove(tmpfile.name)
tmpfile.write(contents.encode('utf-8'))
tmpfile.close()
return tmpfile.name
def _create_file_commit(self, change_id=None, message_prefix=None):
filename = self._create_file()
self.repo.git.add(filename)
message = "Adding %s" % os.path.basename(filename)
if message_prefix:
message = "%s %s" % (message_prefix, message)
if change_id:
message = message + "\n\nChange-Id: %s" % change_id
self.repo.git.commit(m=message)
def add_commits(self, num=None, ref="HEAD", change_ids=[],
message_prefix=None):
"""Create the given number of commits using generated files"""
if ref != "HEAD":
self.repo.git.checkout(ref)
if num is None:
num = max(1, len(change_ids))
ids = list(change_ids) + [None] * (num - len(change_ids))
for x in range(num):
self._create_file_commit(
change_id=ids[x], message_prefix=message_prefix)