293 lines
11 KiB
Python
293 lines
11 KiB
Python
# Copyright (c) 2018 Hewlett Packard Enterprise Development Company LP
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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#
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import logging
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import os
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import tempfile
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import faker
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import git
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import voluptuous
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from fixtures_git import exc
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from fixtures_git import _utils
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class GitTree(object):
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"""Helper class to build a git repository from a graph definition
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Helper class to build a git repository from a graph definition of
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nodes and their parent nodes. A list of branches may be provided
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where each element has two members corresponding to the name and the
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target node it references.
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Supports unordered graphs, only requirement is that there is a commit
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defined with no parents, which will become the root commit.
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Root commits can specified by an empty list as the second member:
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('NodeA', [])
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Merge commits are specified by multiple nodes:
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('NodeMerge', ['Node1', 'Node2'])
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An '=' prefix can be used in front of one of the parents of a merge
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commit to indicate that the merge commit's tree should be copied
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directly from that parent ignoring any contributions from the other
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parents' trees (like what git enables with the '-s ours' merge
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strategy.
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This is used when needing to preserve history but not interested in
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the changes from the other branches. One tool that makes extensive
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usage of this is _git-upstream.
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E.g., the following will result in a merge commit 'C', with parents
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'P1' and 'P2', but will have the same tree as 'P1'.
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('C', ['=P1', 'P2'])
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The tree building code can handle a graph definition being out of
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order but will fail to find certain circular dependencies and may
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result in an infinite loop.
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Examples:
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[('A', []), ('B', ['A']), ('C', ['B'])]
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[('A', []), ('C', ['B']), ('B', ['A'])]
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.. _git-upstream: https://pypi.python.org/pypi/git-upstream
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"""
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explicit_schema_validator = voluptuous.Schema({
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voluptuous.Required('name'): str,
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'message': str,
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'files': dict,
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'author': str,
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'parents': list,
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}
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)
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simple_schema_validator = voluptuous.Schema(
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voluptuous.ExactSequence(
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[str, voluptuous.Schema([str])]
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)
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)
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def __init__(self, repo, tree, branches):
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self.logger = logging.getLogger(
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"%s.%s" % (__name__, self.__class__.__name__)
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)
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self.graph = {}
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self.repo = repo
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self._file_list = set()
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# for text generation
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self._faker = faker.Faker()
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self._build_git_tree(tree, branches)
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def _commit(self, node):
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p_node = _utils.get_node_to_pick(node)
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if p_node:
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self.repo.git.cherry_pick(self.graph[p_node], x=True)
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else:
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# standard commit
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self.add_commits(1, ref="HEAD", message_prefix="[%s]" % node)
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def _merge_commit(self, node, parents):
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# merge commits
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parent_nodes = [p.lstrip("=") for p in parents]
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commits = [str(self.graph[p]) for p in parent_nodes[1:]]
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if any([p.startswith("=") for p in parents]):
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# special merge commit using inverse of 'ours' by
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# emptying the current index and then reading in any
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# trees of the nodes prefixed with '='
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use = [str(self.graph[p.lstrip("=")])
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for p in parents if p.startswith("=")]
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try:
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self.repo.git.merge(*commits, s="ours", no_commit=True)
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except git.exc.GitCommandError as exc:
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if 'refusing to merge unrelated histories' in exc.stderr:
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self.repo.git.merge(*commits, s="ours", no_commit=True,
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allow_unrelated_histories=True)
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else:
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raise
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self.repo.git.read_tree(empty=True)
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self.repo.git.read_tree(empty=True)
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self.repo.git.read_tree(*use, u=True, reset=True)
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elif len(commits) < 2:
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# standard merge
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try:
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self.repo.git.merge(*commits, no_commit=True)
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except git.exc.GitCommandError as exc:
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if 'refusing to merge unrelated histories' in exc.stderr:
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self.repo.git.merge(*commits, no_commit=True,
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allow_unrelated_histories=True)
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else:
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raise
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else:
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# multi-branch merge, git is not great at handling
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# merging multiple orphaned branches
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try:
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self.repo.git.merge(*commits, s="ours", no_commit=True)
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except git.exc.GitCommandError as exc:
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if 'refusing to merge unrelated histories' in exc.stderr:
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self.repo.git.merge(*commits, s="ours", no_commit=True,
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allow_unrelated_histories=True)
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else:
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raise
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self.repo.git.read_tree(empty=True)
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self.repo.git.read_tree("HEAD", *commits)
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self.repo.git.checkout("--", ".")
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self.repo.git.commit(m="[%s] Merging %s into %s" %
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(node, ",".join(parent_nodes[1:]),
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parent_nodes[0]))
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self.repo.git.clean(f=True, d=True, x=True)
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def _build_git_tree(self, graph_def, branches=None):
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if branches is None:
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branches = []
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# validate graph definition
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node1 = graph_def[0]
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if isinstance(node1, dict):
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validator = self.explicit_schema_validator
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err_msg = "Does not conform to explicit style format."
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elif isinstance(node1, list):
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validator = self.simple_schema_validator
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err_msg = "Does not conform to simple style format."
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else:
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raise exc.InvalidGraphFormat(
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"Unknown graph format or unable to guess from '%s'" % node1
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)
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try:
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for c in graph_def:
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validator(c)
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except (voluptuous.Invalid, voluptuous.MultipleInvalid) as err:
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self.logger.error(
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"Validation of '%s' failed with error '%s'", c, err
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)
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raise exc.InvalidGraphFormat(
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"Invalid graph structure: %s" % err_msg
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)
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if isinstance(graph_def[0], dict):
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# need to generate a suitable graph_def to walk
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raise RuntimeError("Explicit schema not yet handled")
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# require that graphs must have at least 1 node with no
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# parents, which is a root commit in git
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if not any([True for _, parents in graph_def if not parents]):
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raise BadGraphDefinition("No root commit defined in test graph")
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for node, parents in _utils.reverse_toposort(graph_def):
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if not parents:
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# root commit
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self.repo.git.symbolic_ref("HEAD", "refs/heads/%s" % node)
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self.repo.git.rm(".", r=True, cached=True,
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with_exceptions=False)
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self.repo.git.clean(f=True, d=True, x=True)
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self.add_commits(1, ref="HEAD", message_prefix="[%s]" % node)
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# only explicitly listed branches should exist afterwards
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self.repo.git.checkout(self.repo.commit())
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self.repo.git.branch(node, D=True)
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else:
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# checkout the dependent node
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self.repo.git.checkout(self.graph[parents[0].lstrip('=')])
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if len(parents) > 1:
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# merge commits
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self._merge_commit(node, parents)
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else:
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self._commit(node)
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self.graph[node] = self.repo.commit()
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# handle branches being specified in explicit or simple
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if isinstance(branches, dict):
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# explicit format
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list_branches = branches.items()
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else:
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# simple format
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list_branches = branches
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for name, node in list_branches:
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if isinstance(node, list):
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name, node = node
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else:
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node = node
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if node in branches:
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node = branches[node]
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self.repo.git.branch(name, str(self.graph[node]), f=True)
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# return to master
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self.repo.git.checkout("master")
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def _create_file(self):
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contents = "\n\n".join(self._faker.paragraphs(3))
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# always want to ensure the files added to the repo are unique no
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# matter which branch they are added to, as otherwise there may
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# be conflicts caused by replaying local changes and performing
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# merges
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while True:
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tmpfile = tempfile.NamedTemporaryFile(
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dir=self.repo.working_dir, delete=False)
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if tmpfile.name not in self._file_list:
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self._file_list.add(tmpfile.name)
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break
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# case where same filename in use on a different branch
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tmpfile.close()
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os.remove(tmpfile.name)
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tmpfile.write(contents.encode('utf-8'))
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tmpfile.close()
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return tmpfile.name
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def _create_file_commit(self, change_id=None, message_prefix=None):
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filename = self._create_file()
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self.repo.git.add(filename)
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message = "Adding %s" % os.path.basename(filename)
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if message_prefix:
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message = "%s %s" % (message_prefix, message)
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if change_id:
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message = message + "\n\nChange-Id: %s" % change_id
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self.repo.git.commit(m=message)
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def add_commits(self, num=None, ref="HEAD", change_ids=None,
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message_prefix=None):
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"""Create the given number of commits using generated files"""
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if change_ids is None:
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change_ids = []
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if ref != "HEAD":
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self.repo.git.checkout(ref)
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if num is None:
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num = max(1, len(change_ids))
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ids = list(change_ids) + [None] * (num - len(change_ids))
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for x in range(num):
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self._create_file_commit(
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change_id=ids[x], message_prefix=message_prefix)
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def commits_from_nodes(self, nodes):
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return [self.graph[n] for n in nodes]
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