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testing: add interface unit tests for file storage...
testing: add interface unit tests for file storage Our strategy for supporting alternate storage backends is to define interfaces for everything then "code to the interface." We already have interfaces for various primitives, including file and manifest storage. What we don't have is generic unit tests for those interfaces. Up to this point we've been relying on high-level integration tests (mainly in the form of existing .t tests) to test alternate storage backends. And my experience with developing the "simple store" test extension is that such testing is very tedious: it takes several minutes to run all tests and when you find a failure, it is often non-trivial to debug. This commit starts to change that. This commit introduces the mercurial.testing.storage module. It contains testing code for storage. Currently, it defines some unittest.TestCase classes for testing the file storage interfaces. It also defines some factory functions that allow a caller to easily spawn a custom TestCase "bound" to a specific file storage backend implementation. A new .py test has been added. It simply defines a callable to produce filelog and transaction instances on demand and then "registers" the various test classes so the filelog class can be tested with the storage interface unit tests. As part of writing the tests, I identified a couple of apparent bugs in revlog.py and filelog.py! These are tracked with inline TODO comments. Writing the tests makes it more obvious where the storage interface is lacking. For example, we raise either IndexError or error.LookupError for missing revisions depending on whether we use an integer revision or a node. Also, we raise error.RevlogError in various places when we should be raising a storage-agnostic error type. The storage interfaces are currently far from perfect and there is much work to be done to improve them. But at least with this commit we finally have the start of unit tests that can be used to "qualify" the behavior of a storage backend. And when implementing and debugging new storage backends, we now have an obvious place to define new tests and have obvious places to insert breakpoints to facilitate debugging. This should be invaluable when implementing new storage backends. I added the mercurial.testing package because these interface conformance tests are generic and need to be usable by all storage backends. Having the code live in tests/ would make it difficult for storage backends implemented in extensions to test their interface conformance. First, it would require obtaining a copy of Mercurial's storage test code in order to test. Second, it would make testing against multiple Mercurial versions difficult, as you would need to import N copies of the storage testing code in order to achieve test coverage. By making the test code part of the Mercurial distribution itself, extensions can `import mercurial.testing.*` to access and run the test code. The test will run against whatever Mercurial version is active. FWIW I've always wanted to move parts of run-tests.py into the mercurial.* package to make the testing story simpler (e.g. imagine an `hg debugruntests` command that could invoke the test harness). While I have no plans to do that in the near future, establishing the mercurial.testing package does provide a natural home for that code should someone do this in the future. Differential Revision: https://phab.mercurial-scm.org/D4650

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__init__.py
86 lines | 2.8 KiB | text/x-python | PythonLexer
# __init__.py - narrowhg extension
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
'''create clones which fetch history data for subset of files (EXPERIMENTAL)'''
from __future__ import absolute_import
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'
from mercurial import (
extensions,
localrepo,
registrar,
repository,
verify as verifymod,
)
from . import (
narrowbundle2,
narrowcommands,
narrowcopies,
narrowpatch,
narrowrepo,
narrowtemplates,
narrowwirepeer,
)
configtable = {}
configitem = registrar.configitem(configtable)
# Narrowhg *has* support for serving ellipsis nodes (which are used at
# least by Google's internal server), but that support is pretty
# fragile and has a lot of problems on real-world repositories that
# have complex graph topologies. This could probably be corrected, but
# absent someone needing the full support for ellipsis nodes in
# repositories with merges, it's unlikely this work will get done. As
# of this writining in late 2017, all repositories large enough for
# ellipsis nodes to be a hard requirement also enforce strictly linear
# history for other scaling reasons.
configitem('experimental', 'narrowservebrokenellipses',
default=False,
alias=[('narrow', 'serveellipses')],
)
# Export the commands table for Mercurial to see.
cmdtable = narrowcommands.table
def featuresetup(ui, features):
features.add(repository.NARROW_REQUIREMENT)
def uisetup(ui):
"""Wraps user-facing mercurial commands with narrow-aware versions."""
localrepo.featuresetupfuncs.add(featuresetup)
narrowbundle2.setup()
narrowcommands.setup()
narrowwirepeer.uisetup()
def reposetup(ui, repo):
"""Wraps local repositories with narrow repo support."""
if not repo.local():
return
if repository.NARROW_REQUIREMENT in repo.requirements:
narrowrepo.wraprepo(repo)
narrowcopies.setup(repo)
narrowpatch.setup(repo)
narrowwirepeer.reposetup(repo)
def _verifierinit(orig, self, repo, matcher=None):
# The verifier's matcher argument was desgined for narrowhg, so it should
# be None from core. If another extension passes a matcher (unlikely),
# we'll have to fail until matchers can be composed more easily.
assert matcher is None
orig(self, repo, repo.narrowmatch())
def extsetup(ui):
extensions.wrapfunction(verifymod.verifier, '__init__', _verifierinit)
templatekeyword = narrowtemplates.templatekeyword
revsetpredicate = narrowtemplates.revsetpredicate