Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

13 files changed, 1444 insertions, 0 deletions

diff --git a/python/mozversioncontrol/.isort.cfg b/python/mozversioncontrol/.isort.cfg
new file mode 100644
index 0000000000..9fa4dfd66f
--- /dev/null
+++ b/python/mozversioncontrol/.isort.cfg
@@ -0,0 +1,3 @@
+[settings]
+profile=black
+known_first_party=mozversioncontrol
\ No newline at end of file
diff --git a/python/mozversioncontrol/mozversioncontrol/__init__.py b/python/mozversioncontrol/mozversioncontrol/__init__.py
new file mode 100644
index 0000000000..b847adf8f1
--- /dev/null
+++ b/python/mozversioncontrol/mozversioncontrol/__init__.py
@@ -0,0 +1,827 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this,
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import abc
+import errno
+import os
+import re
+import shutil
+import subprocess
+from pathlib import Path
+from typing import Optional, Union
+
+from mach.util import to_optional_path
+from mozfile import which
+from mozpack.files import FileListFinder
+
+
+class MissingVCSTool(Exception):
+    """Represents a failure to find a version control tool binary."""
+
+
+class MissingVCSInfo(Exception):
+    """Represents a general failure to resolve a VCS interface."""
+
+
+class MissingConfigureInfo(MissingVCSInfo):
+    """Represents error finding VCS info from configure data."""
+
+
+class MissingVCSExtension(MissingVCSInfo):
+    """Represents error finding a required VCS extension."""
+
+    def __init__(self, ext):
+        self.ext = ext
+        msg = "Could not detect required extension '{}'".format(self.ext)
+        super(MissingVCSExtension, self).__init__(msg)
+
+
+class InvalidRepoPath(Exception):
+    """Represents a failure to find a VCS repo at a specified path."""
+
+
+class MissingUpstreamRepo(Exception):
+    """Represents a failure to automatically detect an upstream repo."""
+
+
+class CannotDeleteFromRootOfRepositoryException(Exception):
+    """Represents that the code attempted to delete all files from the root of
+    the repository, which is not permitted."""
+
+
+def get_tool_path(tool: Union[str, Path]):
+    tool = Path(tool)
+    """Obtain the path of `tool`."""
+    if tool.is_absolute() and tool.exists():
+        return str(tool)
+
+    path = to_optional_path(which(str(tool)))
+    if not path:
+        raise MissingVCSTool(
+            f"Unable to obtain {tool} path. Try running "
+            "|mach bootstrap| to ensure your environment is up to "
+            "date."
+        )
+    return str(path)
+
+
+class Repository(object):
+    """A class wrapping utility methods around version control repositories.
+
+    This class is abstract and never instantiated. Obtain an instance by
+    calling a ``get_repository_*()`` helper function.
+
+    Clients are recommended to use the object as a context manager. But not
+    all methods require this.
+    """
+
+    __metaclass__ = abc.ABCMeta
+
+    def __init__(self, path: Path, tool: str):
+        self.path = str(path.resolve())
+        self._tool = Path(get_tool_path(tool))
+        self._version = None
+        self._valid_diff_filter = ("m", "a", "d")
+        self._env = os.environ.copy()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, exc_tb):
+        pass
+
+    def _run(self, *args, **runargs):
+        return_codes = runargs.get("return_codes", [])
+
+        cmd = (str(self._tool),) + args
+        try:
+            return subprocess.check_output(
+                cmd, cwd=self.path, env=self._env, universal_newlines=True
+            )
+        except subprocess.CalledProcessError as e:
+            if e.returncode in return_codes:
+                return ""
+            raise
+
+    @property
+    def tool_version(self):
+        """Return the version of the VCS tool in use as a string."""
+        if self._version:
+            return self._version
+        info = self._run("--version").strip()
+        match = re.search("version ([^\+\)]+)", info)
+        if not match:
+            raise Exception("Unable to identify tool version.")
+
+        self.version = match.group(1)
+        return self.version
+
+    @property
+    def has_git_cinnabar(self):
+        """True if the repository is using git cinnabar."""
+        return False
+
+    @abc.abstractproperty
+    def name(self):
+        """Name of the tool."""
+
+    @abc.abstractproperty
+    def head_ref(self):
+        """Hash of HEAD revision."""
+
+    @abc.abstractproperty
+    def base_ref(self):
+        """Hash of revision the current topic branch is based on."""
+
+    @abc.abstractmethod
+    def base_ref_as_hg(self):
+        """Mercurial hash of revision the current topic branch is based on.
+
+        Return None if the hg hash of the base ref could not be calculated.
+        """
+
+    @abc.abstractproperty
+    def branch(self):
+        """Current branch or bookmark the checkout has active."""
+
+    @abc.abstractmethod
+    def get_commit_time(self):
+        """Return the Unix time of the HEAD revision."""
+
+    @abc.abstractmethod
+    def sparse_checkout_present(self):
+        """Whether the working directory is using a sparse checkout.
+
+        A sparse checkout is defined as a working directory that only
+        materializes a subset of files in a given revision.
+
+        Returns a bool.
+        """
+
+    @abc.abstractmethod
+    def get_user_email(self):
+        """Return the user's email address.
+
+        If no email is configured, then None is returned.
+        """
+
+    @abc.abstractmethod
+    def get_upstream(self):
+        """Reference to the upstream remote."""
+
+    @abc.abstractmethod
+    def get_changed_files(self, diff_filter, mode="unstaged", rev=None):
+        """Return a list of files that are changed in this repository's
+        working copy.
+
+        ``diff_filter`` controls which kinds of modifications are returned.
+        It is a string which may only contain the following characters:
+
+            A - Include files that were added
+            D - Include files that were deleted
+            M - Include files that were modified
+
+        By default, all three will be included.
+
+        ``mode`` can be one of 'unstaged', 'staged' or 'all'. Only has an
+        effect on git. Defaults to 'unstaged'.
+
+        ``rev`` is a specifier for which changesets to consider for
+        changes. The exact meaning depends on the vcs system being used.
+        """
+
+    @abc.abstractmethod
+    def get_outgoing_files(self, diff_filter, upstream):
+        """Return a list of changed files compared to upstream.
+
+        ``diff_filter`` works the same as `get_changed_files`.
+        ``upstream`` is a remote ref to compare against. If unspecified,
+        this will be determined automatically. If there is no remote ref,
+        a MissingUpstreamRepo exception will be raised.
+        """
+
+    @abc.abstractmethod
+    def add_remove_files(self, *paths: Union[str, Path]):
+        """Add and remove files under `paths` in this repository's working copy."""
+
+    @abc.abstractmethod
+    def forget_add_remove_files(self, *paths: Union[str, Path]):
+        """Undo the effects of a previous add_remove_files call for `paths`."""
+
+    @abc.abstractmethod
+    def get_tracked_files_finder(self):
+        """Obtain a mozpack.files.BaseFinder of managed files in the working
+        directory.
+
+        The Finder will have its list of all files in the repo cached for its
+        entire lifetime, so operations on the Finder will not track with, for
+        example, commits to the repo during the Finder's lifetime.
+        """
+
+    @abc.abstractmethod
+    def get_ignored_files_finder(self):
+        """Obtain a mozpack.files.BaseFinder of ignored files in the working
+        directory.
+
+        The Finder will have its list of all files in the repo cached for its
+        entire lifetime, so operations on the Finder will not track with, for
+        example, changes to the repo during the Finder's lifetime.
+        """
+
+    @abc.abstractmethod
+    def working_directory_clean(self, untracked=False, ignored=False):
+        """Determine if the working directory is free of modifications.
+
+        Returns True if the working directory does not have any file
+        modifications. False otherwise.
+
+        By default, untracked and ignored files are not considered. If
+        ``untracked`` or ``ignored`` are set, they influence the clean check
+        to factor these file classes into consideration.
+        """
+
+    @abc.abstractmethod
+    def clean_directory(self, path: Union[str, Path]):
+        """Undo all changes (including removing new untracked files) in the
+        given `path`.
+        """
+
+    @abc.abstractmethod
+    def push_to_try(self, message, allow_log_capture=False):
+        """Create a temporary commit, push it to try and clean it up
+        afterwards.
+
+        With mercurial, MissingVCSExtension will be raised if the `push-to-try`
+        extension is not installed. On git, MissingVCSExtension will be raised
+        if git cinnabar is not present.
+
+        If `allow_log_capture` is set to `True`, then the push-to-try will be run using
+        Popen instead of check_call so that the logs can be captured elsewhere.
+        """
+
+    @abc.abstractmethod
+    def update(self, ref):
+        """Update the working directory to the specified reference."""
+
+    def commit(self, message, author=None, date=None, paths=None):
+        """Create a commit using the provided commit message. The author, date,
+        and files/paths to be included may also be optionally provided. The
+        message, author and date arguments must be strings, and are passed as-is
+        to the commit command. Multiline commit messages are supported. The
+        paths argument must be None or an array of strings that represents the
+        set of files and folders to include in the commit.
+        """
+        args = ["commit", "-m", message]
+        if author is not None:
+            if isinstance(self, HgRepository):
+                args = args + ["--user", author]
+            elif isinstance(self, GitRepository):
+                args = args + ["--author", author]
+            else:
+                raise MissingVCSInfo("Unknown repo type")
+        if date is not None:
+            args = args + ["--date", date]
+        if paths is not None:
+            args = args + paths
+        self._run(*args)
+
+    def _push_to_try_with_log_capture(self, cmd, subprocess_opts):
+        """Push to try but with the ability for the user to capture logs.
+
+        We need to use Popen for this because neither the run method nor
+        check_call will allow us to reasonably catch the logs. With check_call,
+        hg hangs, and with the run method, the logs are output too slowly
+        so you're left wondering if it's working (prime candidate for
+        corrupting local repos).
+        """
+        process = subprocess.Popen(cmd, **subprocess_opts)
+
+        # Print out the lines as they appear so they can be
+        # parsed for information
+        for line in process.stdout or []:
+            print(line)
+        process.stdout.close()
+        process.wait()
+
+        if process.returncode != 0:
+            for line in process.stderr or []:
+                print(line)
+            raise subprocess.CalledProcessError("Failed to push-to-try")
+
+
+class HgRepository(Repository):
+    """An implementation of `Repository` for Mercurial repositories."""
+
+    def __init__(self, path: Path, hg="hg"):
+        import hglib.client
+
+        super(HgRepository, self).__init__(path, tool=hg)
+        self._env["HGPLAIN"] = "1"
+
+        # Setting this modifies a global variable and makes all future hglib
+        # instances use this binary. Since the tool path was validated, this
+        # should be OK. But ideally hglib would offer an API that defines
+        # per-instance binaries.
+        hglib.HGPATH = str(self._tool)
+
+        # Without connect=False this spawns a persistent process. We want
+        # the process lifetime tied to a context manager.
+        self._client = hglib.client.hgclient(
+            self.path, encoding="UTF-8", configs=None, connect=False
+        )
+
+    @property
+    def name(self):
+        return "hg"
+
+    @property
+    def head_ref(self):
+        return self._run("log", "-r", ".", "-T", "{node}")
+
+    @property
+    def base_ref(self):
+        return self._run("log", "-r", "last(ancestors(.) and public())", "-T", "{node}")
+
+    def base_ref_as_hg(self):
+        return self.base_ref
+
+    @property
+    def branch(self):
+        bookmarks_fn = Path(self.path) / ".hg" / "bookmarks.current"
+        if bookmarks_fn.exists():
+            with open(bookmarks_fn) as f:
+                bookmark = f.read()
+                return bookmark or None
+
+        return None
+
+    def __enter__(self):
+        if self._client.server is None:
+            # The cwd if the spawned process should be the repo root to ensure
+            # relative paths are normalized to it.
+            old_cwd = Path.cwd()
+            try:
+                os.chdir(self.path)
+                self._client.open()
+            finally:
+                os.chdir(old_cwd)
+
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self._client.close()
+
+    def _run(self, *args, **runargs):
+        if not self._client.server:
+            return super(HgRepository, self)._run(*args, **runargs)
+
+        # hglib requires bytes on python 3
+        args = [a.encode("utf-8") if not isinstance(a, bytes) else a for a in args]
+        return self._client.rawcommand(args).decode("utf-8")
+
+    def get_commit_time(self):
+        newest_public_revision_time = self._run(
+            "log",
+            "--rev",
+            "heads(ancestors(.) and not draft())",
+            "--template",
+            "{word(0, date|hgdate)}",
+            "--limit",
+            "1",
+        ).strip()
+
+        if not newest_public_revision_time:
+            raise RuntimeError(
+                "Unable to find a non-draft commit in this hg "
+                "repository. If you created this repository from a "
+                'bundle, have you done a "hg pull" from hg.mozilla.org '
+                "since?"
+            )
+
+        return int(newest_public_revision_time)
+
+    def sparse_checkout_present(self):
+        # We assume a sparse checkout is enabled if the .hg/sparse file
+        # has data. Strictly speaking, we should look for a requirement in
+        # .hg/requires. But since the requirement is still experimental
+        # as of Mercurial 4.3, it's probably more trouble than its worth
+        # to verify it.
+        sparse = Path(self.path) / ".hg" / "sparse"
+
+        try:
+            st = sparse.stat()
+            return st.st_size > 0
+        except OSError as e:
+            if e.errno != errno.ENOENT:
+                raise
+
+            return False
+
+    def get_user_email(self):
+        # Output is in the form "First Last <flast@mozilla.com>"
+        username = self._run("config", "ui.username", return_codes=[0, 1])
+        if not username:
+            # No username is set
+            return None
+        match = re.search(r"<(.*)>", username)
+        if not match:
+            # "ui.username" doesn't follow the "Full Name <email@domain>" convention
+            return None
+        return match.group(1)
+
+    def get_upstream(self):
+        return "default"
+
+    def _format_diff_filter(self, diff_filter, for_status=False):
+        df = diff_filter.lower()
+        assert all(f in self._valid_diff_filter for f in df)
+
+        # When looking at the changes in the working directory, the hg status
+        # command uses 'd' for files that have been deleted with a non-hg
+        # command, and 'r' for files that have been `hg rm`ed. Use both.
+        return df.replace("d", "dr") if for_status else df
+
+    def _files_template(self, diff_filter):
+        template = ""
+        df = self._format_diff_filter(diff_filter)
+        if "a" in df:
+            template += "{file_adds % '{file}\\n'}"
+        if "d" in df:
+            template += "{file_dels % '{file}\\n'}"
+        if "m" in df:
+            template += "{file_mods % '{file}\\n'}"
+        return template
+
+    def get_changed_files(self, diff_filter="ADM", mode="unstaged", rev=None):
+        if rev is None:
+            # Use --no-status to print just the filename.
+            df = self._format_diff_filter(diff_filter, for_status=True)
+            return self._run("status", "--no-status", "-{}".format(df)).splitlines()
+        else:
+            template = self._files_template(diff_filter)
+            return self._run("log", "-r", rev, "-T", template).splitlines()
+
+    def get_outgoing_files(self, diff_filter="ADM", upstream=None):
+        template = self._files_template(diff_filter)
+
+        if not upstream:
+            return self._run(
+                "log", "-r", "draft() and ancestors(.)", "--template", template
+            ).split()
+
+        return self._run(
+            "outgoing",
+            "-r",
+            ".",
+            "--quiet",
+            "--template",
+            template,
+            upstream,
+            return_codes=(1,),
+        ).split()
+
+    def add_remove_files(self, *paths: Union[str, Path]):
+        if not paths:
+            return
+
+        paths = [str(path) for path in paths]
+
+        args = ["addremove"] + paths
+        m = re.search(r"\d+\.\d+", self.tool_version)
+        simplified_version = float(m.group(0)) if m else 0
+        if simplified_version >= 3.9:
+            args = ["--config", "extensions.automv="] + args
+        self._run(*args)
+
+    def forget_add_remove_files(self, *paths: Union[str, Path]):
+        if not paths:
+            return
+
+        paths = [str(path) for path in paths]
+
+        self._run("forget", *paths)
+
+    def get_tracked_files_finder(self):
+        # Can return backslashes on Windows. Normalize to forward slashes.
+        files = list(
+            p.replace("\\", "/") for p in self._run("files", "-0").split("\0") if p
+        )
+        return FileListFinder(files)
+
+    def get_ignored_files_finder(self):
+        # Can return backslashes on Windows. Normalize to forward slashes.
+        files = list(
+            p.replace("\\", "/").split(" ")[-1]
+            for p in self._run("status", "-i").split("\n")
+            if p
+        )
+        return FileListFinder(files)
+
+    def working_directory_clean(self, untracked=False, ignored=False):
+        args = ["status", "--modified", "--added", "--removed", "--deleted"]
+        if untracked:
+            args.append("--unknown")
+        if ignored:
+            args.append("--ignored")
+
+        # If output is empty, there are no entries of requested status, which
+        # means we are clean.
+        return not len(self._run(*args).strip())
+
+    def clean_directory(self, path: Union[str, Path]):
+        if Path(self.path).samefile(path):
+            raise CannotDeleteFromRootOfRepositoryException()
+        self._run("revert", str(path))
+        for single_path in self._run("st", "-un", str(path)).splitlines():
+            single_path = Path(single_path)
+            if single_path.is_file():
+                single_path.unlink()
+            else:
+                shutil.rmtree(str(single_path))
+
+    def update(self, ref):
+        return self._run("update", "--check", ref)
+
+    def push_to_try(self, message, allow_log_capture=False):
+        try:
+            cmd = (str(self._tool), "push-to-try", "-m", message)
+            if allow_log_capture:
+                self._push_to_try_with_log_capture(
+                    cmd,
+                    {
+                        "stdout": subprocess.PIPE,
+                        "stderr": subprocess.PIPE,
+                        "cwd": self.path,
+                        "env": self._env,
+                        "universal_newlines": True,
+                        "bufsize": 1,
+                    },
+                )
+            else:
+                subprocess.check_call(
+                    cmd,
+                    cwd=self.path,
+                    env=self._env,
+                )
+        except subprocess.CalledProcessError:
+            try:
+                self._run("showconfig", "extensions.push-to-try")
+            except subprocess.CalledProcessError:
+                raise MissingVCSExtension("push-to-try")
+            raise
+        finally:
+            self._run("revert", "-a")
+
+
+class GitRepository(Repository):
+    """An implementation of `Repository` for Git repositories."""
+
+    def __init__(self, path: Path, git="git"):
+        super(GitRepository, self).__init__(path, tool=git)
+
+    @property
+    def name(self):
+        return "git"
+
+    @property
+    def head_ref(self):
+        return self._run("rev-parse", "HEAD").strip()
+
+    @property
+    def base_ref(self):
+        refs = self._run(
+            "rev-list", "HEAD", "--topo-order", "--boundary", "--not", "--remotes"
+        ).splitlines()
+        if refs:
+            return refs[-1][1:]  # boundary starts with a prefix `-`
+        return self.head_ref
+
+    def base_ref_as_hg(self):
+        base_ref = self.base_ref
+        try:
+            return self._run("cinnabar", "git2hg", base_ref)
+        except subprocess.CalledProcessError:
+            return
+
+    @property
+    def branch(self):
+        return self._run("branch", "--show-current").strip() or None
+
+    @property
+    def has_git_cinnabar(self):
+        try:
+            self._run("cinnabar", "--version")
+        except subprocess.CalledProcessError:
+            return False
+        return True
+
+    def get_commit_time(self):
+        return int(self._run("log", "-1", "--format=%ct").strip())
+
+    def sparse_checkout_present(self):
+        # Not yet implemented.
+        return False
+
+    def get_user_email(self):
+        email = self._run("config", "user.email", return_codes=[0, 1])
+        if not email:
+            return None
+        return email.strip()
+
+    def get_upstream(self):
+        ref = self._run("symbolic-ref", "-q", "HEAD").strip()
+        upstream = self._run("for-each-ref", "--format=%(upstream:short)", ref).strip()
+
+        if not upstream:
+            raise MissingUpstreamRepo("Could not detect an upstream repository.")
+
+        return upstream
+
+    def get_changed_files(self, diff_filter="ADM", mode="unstaged", rev=None):
+        assert all(f.lower() in self._valid_diff_filter for f in diff_filter)
+
+        if rev is None:
+            cmd = ["diff"]
+            if mode == "staged":
+                cmd.append("--cached")
+            elif mode == "all":
+                cmd.append("HEAD")
+        else:
+            cmd = ["diff-tree", "-r", "--no-commit-id", rev]
+
+        cmd.append("--name-only")
+        cmd.append("--diff-filter=" + diff_filter.upper())
+
+        return self._run(*cmd).splitlines()
+
+    def get_outgoing_files(self, diff_filter="ADM", upstream=None):
+        assert all(f.lower() in self._valid_diff_filter for f in diff_filter)
+
+        not_condition = upstream if upstream else "--remotes"
+
+        files = self._run(
+            "log",
+            "--name-only",
+            "--diff-filter={}".format(diff_filter.upper()),
+            "--oneline",
+            "--pretty=format:",
+            "HEAD",
+            "--not",
+            not_condition,
+        ).splitlines()
+        return [f for f in files if f]
+
+    def add_remove_files(self, *paths: Union[str, Path]):
+        if not paths:
+            return
+
+        paths = [str(path) for path in paths]
+
+        self._run("add", *paths)
+
+    def forget_add_remove_files(self, *paths: Union[str, Path]):
+        if not paths:
+            return
+
+        paths = [str(path) for path in paths]
+
+        self._run("reset", *paths)
+
+    def get_tracked_files_finder(self):
+        files = [p for p in self._run("ls-files", "-z").split("\0") if p]
+        return FileListFinder(files)
+
+    def get_ignored_files_finder(self):
+        files = [
+            p
+            for p in self._run(
+                "ls-files", "-i", "-o", "-z", "--exclude-standard"
+            ).split("\0")
+            if p
+        ]
+        return FileListFinder(files)
+
+    def working_directory_clean(self, untracked=False, ignored=False):
+        args = ["status", "--porcelain"]
+
+        # Even in --porcelain mode, behavior is affected by the
+        # ``status.showUntrackedFiles`` option, which means we need to be
+        # explicit about how to treat untracked files.
+        if untracked:
+            args.append("--untracked-files=all")
+        else:
+            args.append("--untracked-files=no")
+
+        if ignored:
+            args.append("--ignored")
+
+        return not len(self._run(*args).strip())
+
+    def clean_directory(self, path: Union[str, Path]):
+        if Path(self.path).samefile(path):
+            raise CannotDeleteFromRootOfRepositoryException()
+        self._run("checkout", "--", str(path))
+        self._run("clean", "-df", str(path))
+
+    def update(self, ref):
+        self._run("checkout", ref)
+
+    def push_to_try(self, message, allow_log_capture=False):
+        if not self.has_git_cinnabar:
+            raise MissingVCSExtension("cinnabar")
+
+        self._run(
+            "-c", "commit.gpgSign=false", "commit", "--allow-empty", "-m", message
+        )
+        try:
+            cmd = (
+                str(self._tool),
+                "push",
+                "hg::ssh://hg.mozilla.org/try",
+                "+HEAD:refs/heads/branches/default/tip",
+            )
+            if allow_log_capture:
+                self._push_to_try_with_log_capture(
+                    cmd,
+                    {
+                        "stdout": subprocess.PIPE,
+                        "cwd": self.path,
+                        "universal_newlines": True,
+                        "bufsize": 1,
+                    },
+                )
+            else:
+                subprocess.check_call(cmd, cwd=self.path)
+        finally:
+            self._run("reset", "HEAD~")
+
+    def set_config(self, name, value):
+        self._run("config", name, value)
+
+
+def get_repository_object(path: Optional[Union[str, Path]], hg="hg", git="git"):
+    """Get a repository object for the repository at `path`.
+    If `path` is not a known VCS repository, raise an exception.
+    """
+    # If we provide a path to hg that does not match the on-disk casing (e.g.,
+    # because `path` was normcased), then the hg fsmonitor extension will call
+    # watchman with that path and watchman will spew errors.
+    path = Path(path).resolve()
+    if (path / ".hg").is_dir():
+        return HgRepository(path, hg=hg)
+    elif (path / ".git").exists():
+        return GitRepository(path, git=git)
+    else:
+        raise InvalidRepoPath(f"Unknown VCS, or not a source checkout: {path}")
+
+
+def get_repository_from_build_config(config):
+    """Obtain a repository from the build configuration.
+
+    Accepts an object that has a ``topsrcdir`` and ``subst`` attribute.
+    """
+    flavor = config.substs.get("VCS_CHECKOUT_TYPE")
+
+    # If in build mode, only use what configure found. That way we ensure
+    # that everything in the build system can be controlled via configure.
+    if not flavor:
+        raise MissingConfigureInfo(
+            "could not find VCS_CHECKOUT_TYPE "
+            "in build config; check configure "
+            "output and verify it could find a "
+            "VCS binary"
+        )
+
+    if flavor == "hg":
+        return HgRepository(Path(config.topsrcdir), hg=config.substs["HG"])
+    elif flavor == "git":
+        return GitRepository(Path(config.topsrcdir), git=config.substs["GIT"])
+    else:
+        raise MissingVCSInfo("unknown VCS_CHECKOUT_TYPE value: %s" % flavor)
+
+
+def get_repository_from_env():
+    """Obtain a repository object by looking at the environment.
+
+    If inside a build environment (denoted by presence of a ``buildconfig``
+    module), VCS info is obtained from it, as found via configure. This allows
+    us to respect what was passed into configure. Otherwise, we fall back to
+    scanning the filesystem.
+    """
+    try:
+        import buildconfig
+
+        return get_repository_from_build_config(buildconfig)
+    except (ImportError, MissingVCSTool):
+        pass
+
+    paths_to_check = [Path.cwd(), *Path.cwd().parents]
+
+    for path in paths_to_check:
+        try:
+            return get_repository_object(path)
+        except InvalidRepoPath:
+            continue
+
+    raise MissingVCSInfo(f"Could not find Mercurial or Git checkout for {Path.cwd()}")
diff --git a/python/mozversioncontrol/mozversioncontrol/repoupdate.py b/python/mozversioncontrol/mozversioncontrol/repoupdate.py
new file mode 100644
index 0000000000..5336263794
--- /dev/null
+++ b/python/mozversioncontrol/mozversioncontrol/repoupdate.py
@@ -0,0 +1,37 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this,
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import subprocess
+from pathlib import Path
+from typing import Union
+
+# The logic here is far from robust. Improvements are welcome.
+
+
+def update_mercurial_repo(
+    hg: str,
+    repo,
+    path: Union[str, Path],
+    revision="default",
+    hostfingerprints=None,
+    global_args=None,
+):
+    """Ensure a HG repository exists at a path and is up to date."""
+    hostfingerprints = hostfingerprints or {}
+
+    path = Path(path)
+
+    args = [hg]
+    if global_args:
+        args.extend(global_args)
+
+    for host, fingerprint in sorted(hostfingerprints.items()):
+        args.extend(["--config", "hostfingerprints.%s=%s" % (host, fingerprint)])
+
+    if path.exists():
+        subprocess.check_call(args + ["pull", repo], cwd=str(path))
+    else:
+        subprocess.check_call(args + ["clone", repo, str(path)])
+
+    subprocess.check_call([hg, "update", "-r", revision], cwd=str(path))
diff --git a/python/mozversioncontrol/setup.py b/python/mozversioncontrol/setup.py
new file mode 100644
index 0000000000..c0e1aa643f
--- /dev/null
+++ b/python/mozversioncontrol/setup.py
@@ -0,0 +1,28 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from setuptools import find_packages, setup
+
+VERSION = "0.1"
+
+setup(
+    author="Mozilla Foundation",
+    author_email="Mozilla Release Engineering",
+    name="mozversioncontrol",
+    description="Mozilla version control functionality",
+    license="MPL 2.0",
+    packages=find_packages(),
+    version=VERSION,
+    classifiers=[
+        "Development Status :: 3 - Alpha",
+        "Topic :: Software Development :: Build Tools",
+        "License :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)",
+        "Programming Language :: Python :: 2",
+        "Programming Language :: Python :: 2.7",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.5",
+        "Programming Language :: Python :: Implementation :: CPython",
+    ],
+    keywords="mozilla",
+)
diff --git a/python/mozversioncontrol/test/conftest.py b/python/mozversioncontrol/test/conftest.py
new file mode 100644
index 0000000000..78e5ad7ca8
--- /dev/null
+++ b/python/mozversioncontrol/test/conftest.py
@@ -0,0 +1,84 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+SETUP = {
+    "hg": [
+        """
+        echo "foo" > foo
+        echo "bar" > bar
+        hg init
+        hg add *
+        hg commit -m "Initial commit"
+        hg phase --public .
+        """,
+        """
+        echo [paths] > .hg/hgrc
+        echo "default = ../remoterepo" >> .hg/hgrc
+        """,
+    ],
+    "git": [
+        """
+        echo "foo" > foo
+        echo "bar" > bar
+        git init
+        git config user.name "Testing McTesterson"
+        git config user.email "<test@example.org>"
+        git add *
+        git commit -am "Initial commit"
+        """,
+        """
+        git remote add upstream ../remoterepo
+        git fetch upstream
+        git branch -u upstream/master
+        """,
+    ],
+}
+
+
+class RepoTestFixture:
+    def __init__(self, repo_dir: Path, vcs: str, steps: [str]):
+        self.dir = repo_dir
+        self.vcs = vcs
+
+        # This creates a step iterator. Each time execute_next_step()
+        # is called the next set of instructions will be executed.
+        self.steps = (shell(cmd, self.dir) for cmd in steps)
+
+    def execute_next_step(self):
+        next(self.steps)
+
+
+def shell(cmd, working_dir):
+    for step in cmd.split(os.linesep):
+        subprocess.check_call(step, shell=True, cwd=working_dir)
+
+
+@pytest.fixture(params=["git", "hg"])
+def repo(tmpdir, request):
+    tmpdir = Path(tmpdir)
+    vcs = request.param
+    steps = SETUP[vcs]
+
+    if hasattr(request.module, "STEPS"):
+        steps.extend(request.module.STEPS[vcs])
+
+    repo_dir = (tmpdir / "repo").resolve()
+    (tmpdir / "repo").mkdir()
+
+    repo_test_fixture = RepoTestFixture(repo_dir, vcs, steps)
+
+    repo_test_fixture.execute_next_step()
+
+    shutil.copytree(str(repo_dir), str(tmpdir / "remoterepo"))
+
+    repo_test_fixture.execute_next_step()
+
+    yield repo_test_fixture
diff --git a/python/mozversioncontrol/test/python.ini b/python/mozversioncontrol/test/python.ini
new file mode 100644
index 0000000000..79e52bf937
--- /dev/null
+++ b/python/mozversioncontrol/test/python.ini
@@ -0,0 +1,10 @@
+[DEFAULT]
+subsuite=mozversioncontrol
+
+[test_branch.py]
+[test_commit.py]
+[test_context_manager.py]
+[test_push_to_try.py]
+[test_update.py]
+[test_workdir_outgoing.py]
+[test_working_directory.py]
diff --git a/python/mozversioncontrol/test/test_branch.py b/python/mozversioncontrol/test/test_branch.py
new file mode 100644
index 0000000000..7d211f18e8
--- /dev/null
+++ b/python/mozversioncontrol/test/test_branch.py
@@ -0,0 +1,57 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import mozunit
+import pytest
+from looseversion import LooseVersion
+
+from mozversioncontrol import get_repository_object
+
+STEPS = {
+    "hg": [
+        """
+        hg bookmark test
+        """,
+        """
+        echo "bar" > foo
+        hg commit -m "second commit"
+        """,
+    ],
+    "git": [
+        """
+        git checkout -b test
+        """,
+        """
+        echo "bar" > foo
+        git commit -a -m "second commit"
+        """,
+    ],
+}
+
+
+def test_branch(repo):
+    vcs = get_repository_object(repo.dir)
+    if vcs.name == "git" and LooseVersion(vcs.tool_version) < LooseVersion("2.22.0"):
+        pytest.xfail("`git branch --show-current` not implemented yet")
+
+    if vcs.name == "git":
+        assert vcs.branch == "master"
+    else:
+        assert vcs.branch is None
+
+    repo.execute_next_step()
+    assert vcs.branch == "test"
+
+    repo.execute_next_step()
+    assert vcs.branch == "test"
+
+    vcs.update(vcs.head_ref)
+    assert vcs.branch is None
+
+    vcs.update("test")
+    assert vcs.branch == "test"
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozversioncontrol/test/test_commit.py b/python/mozversioncontrol/test/test_commit.py
new file mode 100644
index 0000000000..b795c0ea6e
--- /dev/null
+++ b/python/mozversioncontrol/test/test_commit.py
@@ -0,0 +1,72 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import mozunit
+
+from mozversioncontrol import get_repository_object
+
+STEPS = {
+    "hg": [
+        """
+        echo "bar" >> bar
+        echo "baz" > foo
+        """,
+    ],
+    "git": [
+        """
+        echo "bar" >> bar
+        echo "baz" > foo
+        """,
+    ],
+}
+
+
+def test_commit(repo):
+    vcs = get_repository_object(repo.dir)
+    assert vcs.working_directory_clean()
+
+    # Modify both foo and bar
+    repo.execute_next_step()
+    assert not vcs.working_directory_clean()
+
+    # Commit just bar
+    vcs.commit(
+        message="Modify bar\n\nbut not baz",
+        author="Testing McTesterson <test@example.org>",
+        date="2017-07-14 02:40:00 UTC",
+        paths=["bar"],
+    )
+
+    # We only committed bar, so foo is still keeping the working dir dirty
+    assert not vcs.working_directory_clean()
+
+    if repo.vcs == "git":
+        log_cmd = ["log", "-1", "--format=%an,%ae,%aD,%B"]
+        patch_cmd = ["log", "-1", "-p"]
+    else:
+        log_cmd = [
+            "log",
+            "-l",
+            "1",
+            "-T",
+            "{person(author)},{email(author)},{date|rfc822date},{desc}",
+        ]
+        patch_cmd = ["log", "-l", "1", "-p"]
+
+    # Verify commit metadata (we rstrip to normalize trivial git/hg differences)
+    log = vcs._run(*log_cmd).rstrip()
+    assert log == (
+        "Testing McTesterson,test@example.org,Fri, 14 "
+        "Jul 2017 02:40:00 +0000,Modify bar\n\nbut not baz"
+    )
+
+    # Verify only the intended file was added to the commit
+    patch = vcs._run(*patch_cmd)
+    diffs = [line for line in patch.splitlines() if "diff --git" in line]
+    assert len(diffs) == 1
+    assert diffs[0] == "diff --git a/bar b/bar"
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozversioncontrol/test/test_context_manager.py b/python/mozversioncontrol/test/test_context_manager.py
new file mode 100644
index 0000000000..3186a144d9
--- /dev/null
+++ b/python/mozversioncontrol/test/test_context_manager.py
@@ -0,0 +1,28 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import mozunit
+
+from mozversioncontrol import get_repository_object
+
+
+def test_context_manager(repo):
+    is_git = repo.vcs == "git"
+    cmd = ["show", "--no-patch"] if is_git else ["tip"]
+
+    vcs = get_repository_object(repo.dir)
+    output_subprocess = vcs._run(*cmd)
+    assert is_git or vcs._client.server is None
+    assert "Initial commit" in output_subprocess
+
+    with vcs:
+        assert is_git or vcs._client.server is not None
+        output_client = vcs._run(*cmd)
+
+    assert is_git or vcs._client.server is None
+    assert output_subprocess == output_client
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozversioncontrol/test/test_push_to_try.py b/python/mozversioncontrol/test/test_push_to_try.py
new file mode 100644
index 0000000000..d0a0b2d993
--- /dev/null
+++ b/python/mozversioncontrol/test/test_push_to_try.py
@@ -0,0 +1,81 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import subprocess
+
+import mozunit
+import pytest
+
+from mozversioncontrol import MissingVCSExtension, get_repository_object
+
+
+def test_push_to_try(repo, monkeypatch):
+    commit_message = "commit message"
+    vcs = get_repository_object(repo.dir)
+
+    captured_commands = []
+
+    def fake_run(*args, **kwargs):
+        captured_commands.append(args[0])
+
+    monkeypatch.setattr(subprocess, "check_output", fake_run)
+    monkeypatch.setattr(subprocess, "check_call", fake_run)
+
+    vcs.push_to_try(commit_message)
+    tool = vcs._tool
+
+    if repo.vcs == "hg":
+        expected = [
+            (str(tool), "push-to-try", "-m", commit_message),
+            (str(tool), "revert", "-a"),
+        ]
+    else:
+        expected = [
+            (str(tool), "cinnabar", "--version"),
+            (
+                str(tool),
+                "-c",
+                "commit.gpgSign=false",
+                "commit",
+                "--allow-empty",
+                "-m",
+                commit_message,
+            ),
+            (
+                str(tool),
+                "push",
+                "hg::ssh://hg.mozilla.org/try",
+                "+HEAD:refs/heads/branches/default/tip",
+            ),
+            (str(tool), "reset", "HEAD~"),
+        ]
+
+    for i, value in enumerate(captured_commands):
+        assert value == expected[i]
+
+    assert len(captured_commands) == len(expected)
+
+
+def test_push_to_try_missing_extensions(repo, monkeypatch):
+    if repo.vcs != "git":
+        return
+
+    vcs = get_repository_object(repo.dir)
+
+    orig = vcs._run
+
+    def cinnabar_raises(*args, **kwargs):
+        # Simulate not having git cinnabar
+        if args[0] == "cinnabar":
+            raise subprocess.CalledProcessError(1, args)
+        return orig(*args, **kwargs)
+
+    monkeypatch.setattr(vcs, "_run", cinnabar_raises)
+
+    with pytest.raises(MissingVCSExtension):
+        vcs.push_to_try("commit message")
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozversioncontrol/test/test_update.py b/python/mozversioncontrol/test/test_update.py
new file mode 100644
index 0000000000..91c7469ee5
--- /dev/null
+++ b/python/mozversioncontrol/test/test_update.py
@@ -0,0 +1,63 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from subprocess import CalledProcessError
+
+import mozunit
+import pytest
+
+from mozversioncontrol import get_repository_object
+
+STEPS = {
+    "hg": [
+        """
+        echo "bar" >> bar
+        echo "baz" > foo
+        hg commit -m "second commit"
+        """,
+        """
+        echo "foobar" > foo
+        """,
+    ],
+    "git": [
+        """
+        echo "bar" >> bar
+        echo "baz" > foo
+        git add *
+        git commit -m "second commit"
+        """,
+        """
+        echo "foobar" > foo
+        """,
+    ],
+}
+
+
+def test_update(repo):
+    vcs = get_repository_object(repo.dir)
+    rev0 = vcs.head_ref
+
+    repo.execute_next_step()
+    rev1 = vcs.head_ref
+    assert rev0 != rev1
+
+    if repo.vcs == "hg":
+        vcs.update(".~1")
+    else:
+        vcs.update("HEAD~1")
+    assert vcs.head_ref == rev0
+
+    vcs.update(rev1)
+    assert vcs.head_ref == rev1
+
+    # Update should fail with dirty working directory.
+    repo.execute_next_step()
+    with pytest.raises(CalledProcessError):
+        vcs.update(rev0)
+
+    assert vcs.head_ref == rev1
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozversioncontrol/test/test_workdir_outgoing.py b/python/mozversioncontrol/test/test_workdir_outgoing.py
new file mode 100644
index 0000000000..7bf2e6ec57
--- /dev/null
+++ b/python/mozversioncontrol/test/test_workdir_outgoing.py
@@ -0,0 +1,108 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os
+
+import mozunit
+
+from mozversioncontrol import get_repository_object
+
+STEPS = {
+    "hg": [
+        """
+        echo "bar" >> bar
+        echo "baz" > baz
+        hg add baz
+        hg rm foo
+        """,
+        """
+        hg commit -m "Remove foo; modify bar; add baz"
+        """,
+        """
+        echo ooka >> baz
+        echo newborn > baby
+        hg add baby
+        """,
+        """
+        hg commit -m "Modify baz; add baby"
+        """,
+    ],
+    "git": [
+        """
+        echo "bar" >> bar
+        echo "baz" > baz
+        git add baz
+        git rm foo
+        """,
+        """
+        git commit -am "Remove foo; modify bar; add baz"
+        """,
+        """
+        echo ooka >> baz
+        echo newborn > baby
+        git add baz baby
+        """,
+        """
+        git commit -m "Modify baz; add baby"
+        """,
+    ],
+}
+
+
+def assert_files(actual, expected):
+    assert set(map(os.path.basename, actual)) == set(expected)
+
+
+def test_workdir_outgoing(repo):
+    vcs = get_repository_object(repo.dir)
+    assert vcs.path == str(repo.dir)
+
+    remote_path = "../remoterepo" if repo.vcs == "hg" else "upstream/master"
+
+    # Mutate files.
+    repo.execute_next_step()
+
+    assert_files(vcs.get_changed_files("A", "all"), ["baz"])
+    assert_files(vcs.get_changed_files("AM", "all"), ["bar", "baz"])
+    assert_files(vcs.get_changed_files("D", "all"), ["foo"])
+    if repo.vcs == "git":
+        assert_files(vcs.get_changed_files("AM", mode="staged"), ["baz"])
+    elif repo.vcs == "hg":
+        # Mercurial does not use a staging area (and ignores the mode parameter.)
+        assert_files(vcs.get_changed_files("AM", "unstaged"), ["bar", "baz"])
+    assert_files(vcs.get_outgoing_files("AMD"), [])
+    assert_files(vcs.get_outgoing_files("AMD", remote_path), [])
+
+    # Create a commit.
+    repo.execute_next_step()
+
+    assert_files(vcs.get_changed_files("AMD", "all"), [])
+    assert_files(vcs.get_changed_files("AMD", "staged"), [])
+    assert_files(vcs.get_outgoing_files("AMD"), ["bar", "baz", "foo"])
+    assert_files(vcs.get_outgoing_files("AMD", remote_path), ["bar", "baz", "foo"])
+
+    # Mutate again.
+    repo.execute_next_step()
+
+    assert_files(vcs.get_changed_files("A", "all"), ["baby"])
+    assert_files(vcs.get_changed_files("AM", "all"), ["baby", "baz"])
+    assert_files(vcs.get_changed_files("D", "all"), [])
+
+    # Create a second commit.
+    repo.execute_next_step()
+
+    assert_files(vcs.get_outgoing_files("AM"), ["bar", "baz", "baby"])
+    assert_files(vcs.get_outgoing_files("AM", remote_path), ["bar", "baz", "baby"])
+    if repo.vcs == "git":
+        assert_files(vcs.get_changed_files("AM", rev="HEAD~1"), ["bar", "baz"])
+        assert_files(vcs.get_changed_files("AM", rev="HEAD"), ["baby", "baz"])
+    else:
+        assert_files(vcs.get_changed_files("AM", rev=".^"), ["bar", "baz"])
+        assert_files(vcs.get_changed_files("AM", rev="."), ["baby", "baz"])
+        assert_files(vcs.get_changed_files("AM", rev=".^::"), ["bar", "baz", "baby"])
+        assert_files(vcs.get_changed_files("AM", rev="modifies(baz)"), ["baz", "baby"])
+
+
+if __name__ == "__main__":
+    mozunit.main()
diff --git a/python/mozversioncontrol/test/test_working_directory.py b/python/mozversioncontrol/test/test_working_directory.py
new file mode 100644
index 0000000000..00094a0cc4
--- /dev/null
+++ b/python/mozversioncontrol/test/test_working_directory.py
@@ -0,0 +1,46 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import mozunit
+
+from mozversioncontrol import get_repository_object
+
+STEPS = {
+    "hg": [
+        """
+        echo "bar" >> bar
+        echo "baz" > baz
+        hg rm foo
+        """,
+        """
+        hg commit -m "Remove foo; modify bar; touch baz (but don't add it)"
+        """,
+    ],
+    "git": [
+        """
+        echo "bar" >> bar
+        echo "baz" > baz
+        git rm foo
+        """,
+        """
+        git commit -am "Remove foo; modify bar; touch baz (but don't add it)"
+        """,
+    ],
+}
+
+
+def test_working_directory_clean_untracked_files(repo):
+    vcs = get_repository_object(repo.dir)
+    assert vcs.working_directory_clean()
+
+    repo.execute_next_step()
+    assert not vcs.working_directory_clean()
+
+    repo.execute_next_step()
+    assert vcs.working_directory_clean()
+    assert not vcs.working_directory_clean(untracked=True)
+
+
+if __name__ == "__main__":
+    mozunit.main()