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EDIT :: context.py

import os import subprocess import contextlib import functools import tempfile import shutil import operator import warnings @contextlib.contextmanager def pushd(dir): """ >>> tmp_path = getfixture('tmp_path') >>> with pushd(tmp_path): ... assert os.getcwd() == os.fspath(tmp_path) >>> assert os.getcwd() != os.fspath(tmp_path) """ orig = os.getcwd() os.chdir(dir) try: yield dir finally: os.chdir(orig) @contextlib.contextmanager def tarball_context(url, target_dir=None, runner=None, pushd=pushd): """ Get a tarball, extract it, change to that directory, yield, then clean up. `runner` is the function to invoke commands. `pushd` is a context manager for changing the directory. """ if target_dir is None: target_dir = os.path.basename(url).replace('.tar.gz', '').replace('.tgz', '') if runner is None: runner = functools.partial(subprocess.check_call, shell=True) else: warnings.warn("runner parameter is deprecated", DeprecationWarning) # In the tar command, use --strip-components=1 to strip the first path and # then # use -C to cause the files to be extracted to {target_dir}. This ensures # that we always know where the files were extracted. runner('mkdir {target_dir}'.format(**vars())) try: getter = 'wget {url} -O -' extract = 'tar x{compression} --strip-components=1 -C {target_dir}' cmd = ' | '.join((getter, extract)) runner(cmd.format(compression=infer_compression(url), **vars())) with pushd(target_dir): yield target_dir finally: runner('rm -Rf {target_dir}'.format(**vars())) def infer_compression(url): """ Given a URL or filename, infer the compression code for tar. >>> infer_compression('http://foo/bar.tar.gz') 'z' >>> infer_compression('http://foo/bar.tgz') 'z' >>> infer_compression('file.bz') 'j' >>> infer_compression('file.xz') 'J' """ # cheat and just assume it's the last two characters compression_indicator = url[-2:] mapping = dict(gz='z', bz='j', xz='J') # Assume 'z' (gzip) if no match return mapping.get(compression_indicator, 'z') @contextlib.contextmanager def temp_dir(remover=shutil.rmtree): """ Create a temporary directory context. Pass a custom remover to override the removal behavior. >>> import pathlib >>> with temp_dir() as the_dir: ... assert os.path.isdir(the_dir) ... _ = pathlib.Path(the_dir).joinpath('somefile').write_text('contents') >>> assert not os.path.exists(the_dir) """ temp_dir = tempfile.mkdtemp() try: yield temp_dir finally: remover(temp_dir) @contextlib.contextmanager def repo_context(url, branch=None, quiet=True, dest_ctx=temp_dir): """ Check out the repo indicated by url. If dest_ctx is supplied, it should be a context manager to yield the target directory for the check out. """ exe = 'git' if 'git' in url else 'hg' with dest_ctx() as repo_dir: cmd = [exe, 'clone', url, repo_dir] if branch: cmd.extend(['--branch', branch]) devnull = open(os.path.devnull, 'w') stdout = devnull if quiet else None subprocess.check_call(cmd, stdout=stdout) yield repo_dir @contextlib.contextmanager def null(): """ A null context suitable to stand in for a meaningful context. >>> with null() as value: ... assert value is None """ yield class ExceptionTrap: """ A context manager that will catch certain exceptions and provide an indication they occurred. >>> with ExceptionTrap() as trap: ... raise Exception() >>> bool(trap) True >>> with ExceptionTrap() as trap: ... pass >>> bool(trap) False >>> with ExceptionTrap(ValueError) as trap: ... raise ValueError("1 + 1 is not 3") >>> bool(trap) True >>> trap.value ValueError('1 + 1 is not 3') >>> trap.tb <traceback object at ...> >>> with ExceptionTrap(ValueError) as trap: ... raise Exception() Traceback (most recent call last): ... Exception >>> bool(trap) False """ exc_info = None, None, None def __init__(self, exceptions=(Exception,)): self.exceptions = exceptions def __enter__(self): return self @property def type(self): return self.exc_info[0] @property def value(self): return self.exc_info[1] @property def tb(self): return self.exc_info[2] def __exit__(self, *exc_info): type = exc_info[0] matches = type and issubclass(type, self.exceptions) if matches: self.exc_info = exc_info return matches def __bool__(self): return bool(self.type) def raises(self, func, *, _test=bool): """ Wrap func and replace the result with the truth value of the trap (True if an exception occurred). First, give the decorator an alias to support Python 3.8 Syntax. >>> raises = ExceptionTrap(ValueError).raises Now decorate a function that always fails. >>> @raises ... def fail(): ... raise ValueError('failed') >>> fail() True """ @functools.wraps(func) def wrapper(*args, **kwargs): with ExceptionTrap(self.exceptions) as trap: func(*args, **kwargs) return _test(trap) return wrapper def passes(self, func): """ Wrap func and replace the result with the truth value of the trap (True if no exception). First, give the decorator an alias to support Python 3.8 Syntax. >>> passes = ExceptionTrap(ValueError).passes Now decorate a function that always fails. >>> @passes ... def fail(): ... raise ValueError('failed') >>> fail() False """ return self.raises(func, _test=operator.not_) class suppress(contextlib.suppress, contextlib.ContextDecorator): """ A version of contextlib.suppress with decorator support. >>> @suppress(KeyError) ... def key_error(): ... {}[''] >>> key_error() """ class on_interrupt(contextlib.ContextDecorator): """ Replace a KeyboardInterrupt with SystemExit(1) >>> def do_interrupt(): ... raise KeyboardInterrupt() >>> on_interrupt('error')(do_interrupt)() Traceback (most recent call last): ... SystemExit: 1 >>> on_interrupt('error', code=255)(do_interrupt)() Traceback (most recent call last): ... SystemExit: 255 >>> on_interrupt('suppress')(do_interrupt)() >>> with __import__('pytest').raises(KeyboardInterrupt): ... on_interrupt('ignore')(do_interrupt)() """ def __init__( self, action='error', # py3.7 compat # /, code=1, ): self.action = action self.code = code def __enter__(self): return self def __exit__(self, exctype, excinst, exctb): if exctype is not KeyboardInterrupt or self.action == 'ignore': return elif self.action == 'error': raise SystemExit(self.code) from excinst return self.action == 'suppress'

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