forked from s_ranjbar/city_retrofit
151 lines
4.8 KiB
Python
151 lines
4.8 KiB
Python
import contextlib
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import json
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import os
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import shutil
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import sys
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import tempfile
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__all__ = ['MockCommand', 'assert_calls']
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pkgdir = os.path.dirname(__file__)
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recording_dir = None
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def prepend_to_path(dir):
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os.environ['PATH'] = dir + os.pathsep + os.environ['PATH']
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def remove_from_path(dir):
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path_dirs = os.environ['PATH'].split(os.pathsep)
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path_dirs.remove(dir)
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os.environ['PATH'] = os.pathsep.join(path_dirs)
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_record_run = """#!{python}
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import os, sys
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import json
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with open({recording_file!r}, 'a') as f:
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json.dump({{'env': dict(os.environ),
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'argv': sys.argv,
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'cwd': os.getcwd()}},
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f)
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f.write('\\x1e') # ASCII record separator
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"""
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# TODO: Overlapping calls to the same command may interleave writes.
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class MockCommand(object):
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"""Context manager to mock a system command.
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The mock command will be written to a directory at the front of $PATH,
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taking precedence over any existing command with the same name.
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By specifying content as a string, you can determine what running the
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command will do. The default content records each time the command is
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called and exits: you can access these records with mockcmd.get_calls().
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On Windows, the specified content will be run by the Python interpreter in
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use. On Unix, it should start with a shebang (``#!/path/to/interpreter``).
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"""
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def __init__(self, name, content=None):
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global recording_dir
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self.name = name
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self.content = content
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if recording_dir is None:
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recording_dir = tempfile.mkdtemp()
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fd, self.recording_file = tempfile.mkstemp(dir=recording_dir,
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prefix=name, suffix='.json')
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os.close(fd)
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self.command_dir = tempfile.mkdtemp()
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def _copy_exe(self):
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bitness = '64' if (sys.maxsize > 2**32) else '32'
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src = os.path.join(pkgdir, 'cli-%s.exe' % bitness)
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dst = os.path.join(self.command_dir, self.name+'.exe')
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shutil.copy(src, dst)
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@property
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def _cmd_path(self):
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# Can only be used once commands_dir has been set
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p = os.path.join(self.command_dir, self.name)
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if os.name == 'nt':
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p += '-script.py'
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return p
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def __enter__(self):
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if os.path.isfile(self._cmd_path):
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raise EnvironmentError("Command %r already exists at %s" %
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(self.name, self._cmd_path))
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if self.content is None:
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self.content = _record_run.format(python=sys.executable,
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recording_file=self.recording_file)
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with open(self._cmd_path, 'w') as f:
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f.write(self.content)
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if os.name == 'nt':
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self._copy_exe()
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else:
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os.chmod(self._cmd_path, 0o755) # Set executable bit
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prepend_to_path(self.command_dir)
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return self
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def __exit__(self, etype, evalue, tb):
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remove_from_path(self.command_dir)
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shutil.rmtree(self.command_dir, ignore_errors=True)
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def get_calls(self):
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"""Get a list of calls made to this mocked command.
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This relies on the default script content, so it will return an
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empty list if you specified a different content parameter.
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For each time the command was run, the list will contain a dictionary
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with keys argv, env and cwd.
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"""
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if recording_dir is None:
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return []
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if not os.path.isfile(self.recording_file):
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return []
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with open(self.recording_file, 'r') as f:
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# 1E is ASCII record separator, last chunk is empty
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chunks = f.read().split('\x1e')[:-1]
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return [json.loads(c) for c in chunks]
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@contextlib.contextmanager
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def assert_calls(cmd, args=None):
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"""Assert that a block of code runs the given command.
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If args is passed, also check that it was called at least once with the
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given arguments (not including the command name).
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Use as a context manager, e.g.::
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with assert_calls('git'):
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some_function_wrapping_git()
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with assert_calls('git', ['add', myfile]):
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some_other_function()
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"""
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with MockCommand(cmd) as mc:
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yield
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calls = mc.get_calls()
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assert calls != [], "Command %r was not called" % cmd
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if args is not None:
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if not any(args == c['argv'][1:] for c in calls):
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msg = ["Command %r was not called with specified args (%r)" %
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(cmd, args),
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"It was called with these arguments: "]
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for c in calls:
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msg.append(' %r' % c['argv'][1:])
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raise AssertionError('\n'.join(msg))
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