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import pipes
from functools import wraps, partial, reduce
from io import TextIOWrapper
from itertools import chain, zip_longest
from subprocess import STDOUT, PIPE
from tempfile import TemporaryFile
from testfixtures.utils import extend_docstring
from typing import Union, Callable, List, Optional, Sequence, Tuple, Dict
from .mock import Mock, call, _Call as Call
AnyStr = Union[str, bytes]
Command = Union[str, Sequence[str]]
def shell_join(command: Command) -> str:
if not isinstance(command, str):
command = " ".join(pipes.quote(part) for part in command)
return command
class PopenBehaviour(object):
"""
An object representing the behaviour of a :class:`MockPopen` when
simulating a particular command.
"""
def __init__(
self,
stdout: bytes = b'',
stderr: bytes = b'',
returncode: int = 0,
pid: int = 1234,
poll_count: int = 3
):
self.stdout = stdout
self.stderr = stderr
self.returncode = returncode
self.pid = pid
self.poll_count = poll_count
def record(func) -> Callable:
@wraps(func)
def recorder(self, *args, **kw):
self._record((func.__name__,), *args, **kw)
return func(self, *args, **kw)
return recorder
class MockPopenInstance(object):
"""
A mock process as returned by :class:`MockPopen`.
"""
#: A :class:`~unittest.mock.Mock` representing the pipe into this process.
#: This is only set if ``stdin=PIPE`` is passed the constructor.
#: The mock records writes and closes in :attr:`MockPopen.all_calls`.
stdin: Mock = None
#: A file representing standard output from this process.
stdout: TemporaryFile = None
#: A file representing error output from this process.
stderr: TemporaryFile = None
# These are not types as instantiation of this class is an internal implementation detail.
def __init__(self, mock_class, root_call,
args, bufsize=0, executable=None,
stdin=None, stdout=None, stderr=None,
preexec_fn=None, close_fds=False, shell=False, cwd=None,
env=None, universal_newlines=False,
startupinfo=None, creationflags=0, restore_signals=True,
start_new_session=False, pass_fds=(),
encoding=None, errors=None, text=None):
self.mock: Mock = Mock()
self.class_instance_mock: Mock = mock_class.mock.Popen_instance
#: A :func:`unittest.mock.call` representing the call made to instantiate
#: this mock process.
self.root_call: Call = root_call
#: The calls made on this mock process, represented using
#: :func:`~unittest.mock.call` instances.
self.calls: List[Call] = []
self.all_calls: List[Call] = mock_class.all_calls
cmd = shell_join(args)
behaviour = mock_class.commands.get(cmd, mock_class.default_behaviour)
if behaviour is None:
raise KeyError('Nothing specified for command %r' % cmd)
if callable(behaviour):
behaviour = behaviour(command=cmd, stdin=stdin)
self.behaviour: PopenBehaviour = behaviour
stdout_value = behaviour.stdout
stderr_value = behaviour.stderr
if stderr == STDOUT:
line_iterator = chain.from_iterable(zip_longest(
stdout_value.splitlines(True),
stderr_value.splitlines(True)
))
stdout_value = b''.join(l for l in line_iterator if l)
stderr_value = None
self.poll_count: int = behaviour.poll_count
for name, option, mock_value in (
('stdout', stdout, stdout_value),
('stderr', stderr, stderr_value)
):
value = None
if option is PIPE:
value = TemporaryFile()
value.write(mock_value)
value.flush()
value.seek(0)
if universal_newlines or text or encoding:
value = TextIOWrapper(value, encoding=encoding, errors=errors)
setattr(self, name, value)
if stdin == PIPE:
self.stdin = Mock()
for method in 'write', 'close':
record_writes = partial(self._record, ('stdin', method))
getattr(self.stdin, method).side_effect = record_writes
self.pid: int = behaviour.pid
#: The return code of this mock process.
self.returncode: Optional[int] = None
self.args: Command = args
def _record(self, names, *args, **kw):
for mock in self.class_instance_mock, self.mock:
reduce(getattr, names, mock)(*args, **kw)
for base_call, store in (
(call, self.calls),
(self.root_call, self.all_calls)
):
store.append(reduce(getattr, names, base_call)(*args, **kw))
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.wait()
for stream in self.stdout, self.stderr:
if stream:
stream.close()
@record
def wait(self, timeout: float = None) -> int:
"Simulate calls to :meth:`subprocess.Popen.wait`"
self.returncode = self.behaviour.returncode
return self.returncode
@record
def communicate(self, input: AnyStr = None, timeout: float = None) -> Tuple[AnyStr, AnyStr]:
"Simulate calls to :meth:`subprocess.Popen.communicate`"
self.returncode = self.behaviour.returncode
return (self.stdout and self.stdout.read(),
self.stderr and self.stderr.read())
@record
def poll(self) -> Optional[int]:
"Simulate calls to :meth:`subprocess.Popen.poll`"
while self.poll_count and self.returncode is None:
self.poll_count -= 1
return None
# This call to wait() is NOT how poll() behaves in reality.
# poll() NEVER sets the returncode.
# The returncode is *only* ever set by process completion.
# The following is an artifact of the fixture's implementation.
self.returncode = self.behaviour.returncode
return self.returncode
@record
def send_signal(self, signal: int) -> None:
"Simulate calls to :meth:`subprocess.Popen.send_signal`"
pass
@record
def terminate(self) -> None:
"Simulate calls to :meth:`subprocess.Popen.terminate`"
pass
@record
def kill(self) -> None:
"Simulate calls to :meth:`subprocess.Popen.kill`"
pass
class MockPopen(object):
"""
A specialised mock for testing use of :class:`subprocess.Popen`.
An instance of this class can be used in place of the
:class:`subprocess.Popen` and is often inserted where it's needed using
:func:`unittest.mock.patch` or a :class:`~testfixtures.Replacer`.
"""
default_behaviour: PopenBehaviour = None
def __init__(self):
self.commands: Dict[str, PopenBehaviour] = {}
self.mock: Mock = Mock()
#: All calls made using this mock and the objects it returns, represented using
#: :func:`~unittest.mock.call` instances.
self.all_calls: List[Call] = []
def _resolve_behaviour(self, stdout, stderr, returncode,
pid, poll_count, behaviour):
if behaviour is None:
return PopenBehaviour(
stdout, stderr, returncode, pid, poll_count
)
else:
return behaviour
def set_command(
self,
command: str,
stdout: bytes = b'',
stderr: bytes = b'',
returncode: int = 0,
pid: int = 1234,
poll_count: int = 3,
behaviour: Union[PopenBehaviour, Callable] = None
):
"""
Set the behaviour of this mock when it is used to simulate the
specified command.
:param command: A :class:`str` representing the command to be simulated.
"""
self.commands[shell_join(command)] = self._resolve_behaviour(
stdout, stderr, returncode, pid, poll_count, behaviour
)
def set_default(self, stdout=b'', stderr=b'', returncode=0,
pid=1234, poll_count=3, behaviour=None):
"""
Set the behaviour of this mock when it is used to simulate commands
that have no explicit behavior specified using
:meth:`~MockPopen.set_command`.
"""
self.default_behaviour = self._resolve_behaviour(
stdout, stderr, returncode, pid, poll_count, behaviour
)
def __call__(self, *args, **kw):
self.mock.Popen(*args, **kw)
root_call = call.Popen(*args, **kw)
self.all_calls.append(root_call)
return MockPopenInstance(self, root_call, *args, **kw)
set_command_params = """
:param stdout:
:class:`bytes` representing the simulated content written by the process
to the stdout pipe.
:param stderr:
:class:`bytes` representing the simulated content written by the process
to the stderr pipe.
:param returncode:
An integer representing the return code of the simulated process.
:param pid:
An integer representing the process identifier of the simulated
process. This is useful if you have code the prints out the pids
of running processes.
:param poll_count:
Specifies the number of times :meth:`~MockPopenInstance.poll` can be
called before :attr:`~MockPopenInstance.returncode` is set and returned
by :meth:`~MockPopenInstance.poll`.
If supplied, ``behaviour`` must be either a :class:`PopenBehaviour`
instance or a callable that takes the ``command`` string representing
the command to be simulated and the ``stdin`` supplied when instantiating
the :class:`subprocess.Popen` with that command and should
return a :class:`PopenBehaviour` instance.
"""
# add the param docs, so we only have one copy of them!
extend_docstring(set_command_params,
[MockPopen.set_command, MockPopen.set_default])