"""
Module to mock out portions of the dbus library for testing purposes.
This is intended to be used with doctest, something like::
>>> from sugar.testing import mockdbus
>>> mock_service = mockdbus.MockService(
... 'service.name', '/service/path', name='printed_name')
This doesn't actually change anything, yes; you must install the mock
service to get it to run. This actually modifies the dbus module in
place, and should only be used in a process dedicated to testing (you
shouldn't use this in normal code). Next we install the service and
get the interface::
>>> mock_service.install()
>>> import dbus
>>> mock_interface = dbus.Interface(mock_service, 'interface.name')
Before you trigger code that uses this mock service, you have to tell
the service how to respond, like::
>>> mock_interface.make_response('methodName', 'response')
Next time mock_interface.methodName(any arguments) is called, it will
return 'response'. Also, when that method is called it will print
out the call plus the arguments. This works well with doctest, like::
>>> mock_interface.methodName(1, 2)
Called printed_name.interface.name:methodName(1, 2)
'response'
(Note: the first line is printed, the second line is the return value)
It is an error if a method is called that has no response setup,
unless that method is called asynchronously (with reply_handler).
Then the reply_handler will be called as soon as the response has been
created with service.make_response(). By delaying the response you
can force response handlers to run out of order.
"""
import dbus
_installed = False
fake_get_object = None
def _install():
"""
Installs the monkeypatch to dbus. Called automatically when
necessary.
"""
global _installed, fake_get_object
if _installed:
return
bus = dbus.SessionBus()
old_get_object = bus.get_object
fake_get_object = FakeGetObject(old_get_object)
bus.get_object = fake_get_object
_installed = True
# XXX: Do we need to override bus.add_signal_receiver?
class FakeGetObject(object):
"""
The replacement dbus.get_object() function/callable. This
delegates to the real get_object callable, except when a
MockService has been registered.
"""
def __init__(self, real_get_object):
self._real_get_object = real_get_object
self._overrides = {}
def register(self, mock_service, service_name, path):
"""
Registers a MockService instance to the service_name and path.
Calls to dbus.get_object(service_name, path) will now return
this mock_service object.
"""
self._overrides[(service_name, path)] = mock_service
def __call__(self, service_name, path):
override = self._overrides.get((service_name, path), None)
if override is None:
return self._real_get_object(service_name, path)
else:
return override
class MockService(object):
"""
A mock service object. You should first instantiate then install
this object. Once installed, calls to
dbus.get_object(service_name, path) will return this object
instead of a real dbus service object.
"""
def __init__(self, service_name, path, name=None):
self.service_name = service_name
self.path = path
if name is None:
name = self.service_name
self.name = name
self._connections = {}
self._pending_responses = {}
self._pending_requests = {}
def __repr__(self):
if self.name == self.service_name:
return '<%s %s:%s>' % (
self.__class__.__name__,
self.service_name, self.path)
else:
return '<%s %s %s:%s>' % (
self.__class__.__name__,
self.name,
self.service_name, self.path)
def install(self):
"""
Installs this object.
"""
_install()
fake_get_object.register(
self, self.service_name, self.path)
def __getattr__(self, attr, dbus_interface=None):
if attr == 'make_response':
return BoundInterface(self.make_response, dbus_interface)
return MockMethod(self, attr, dbus_interface)
def call(self, meth_name, dbus_interface, *args, **kw):
formatted = [repr(a) for a in args]
formatted.extend(['%s=%r' % item for item in kw.items()])
formatted = ', '.join(formatted)
print 'Called %s.%s:%s(%s)' % (self.name, dbus_interface, meth_name, formatted)
if 'reply_handler' in kw:
reply_handler = kw.pop('reply_handler')
else:
reply_handler = None
if 'error_handler' in kw:
error_handler = kw.pop('error_handler')
else:
error_handler = None
key = (meth_name, dbus_interface)
if reply_handler:
if key in self._pending_requests:
raise ValueError(
"Duplicate requests not yet handled for %s:%s" % (dbus_interface, meth_name))
self._pending_requests[key] = (reply_handler, error_handler)
self.call_reply_handlers()
return
assert error_handler is None, (
"error_handler %s without reply_handler" % error_handler)
if key not in self._pending_responses:
if self._pending_responses:
extra = '(have responses %s)' % self._response_description()
else:
extra = '(have no waiting responses)'
raise ValueError(
"You must call make_response() before %s:%s method "
"is called %s"
% (dbus_interface, meth_name, extra))
error, response = self._pending_responses.pop(key)
if error:
# XXX: Is this how it should be raised?
raise response
else:
return response
def make_response(self, meth_name, response, error=False,
dbus_interface=None):
"""
This is used to generate a response to a method call. If
error is true, then the response object is an exception that
will be raised (or passed to error_handler).
"""
key = (meth_name, dbus_interface)
if key in self._pending_responses:
raise ValueError(
"A response %r is already registered for %s:%s"
% (self._pending_responses[key], dbus_interface, meth_name))
self._pending_responses[key] = (error, response)
def _response_description(self):
result = []
for meth_name, dbus_interface in sorted(self._pending_responses.keys()):
value = self._pending_responses[(meth_name, dbus_interface)]
result.append('%s:%s()=%r' % (dbus_interface, meth_name, value))
return ', '.join(result)
def call_reply_handlers(self):
"""
This calls any reply_handlers that now have responses (or
errors) ready for them. This can be called when a response is
added after an asynchronous method is called, to trigger the
response actually being called.
"""
# XXX: Should make_response automatically call this?
for key in sorted(self._pending_responses.keys()):
if key in self._pending_requests:
error, response = self._pending_responses[key]
reply_handler, error_handler = self._pending_requests[key]
if error:
# XXX: Is this how it should be raised?
error_handler(response)
else:
reply_handler(response)
del self._pending_responses[key]
del self._pending_requests[key]
def connect_to_signal(self, signal, handler_function,
dbus_interface=None, **kw):
self._connections.setdefault((signal, dbus_interface), []).append(
handler_function)
def send_signal(self, signal, dbus_interface=None):
# XXX: This isn't really done
for listener in self._connections.get((signal, dbus_interface), []):
# XXX: Argument?
listener()
@property
def empty(self):
"""
This can be called to at the end of the test to make sure
there's no responses or requests left over.
"""
return (
not self._pending_responses
and not self._pending_requests)
class MockMethod(object):
def __init__(self, obj, meth_name, dbus_interface):
self.obj = obj
self.meth_name = meth_name
self.dbus_interface = dbus_interface
def __repr__(self):
return '<%s.%s:%s method>' % (
self.obj.name, self.meth_name, self.dbus_interface)
def __call__(self, *args, **kw):
return self.obj.call(
self.meth_name, self.dbus_interface,
*args, **kw)
class BoundInterface(object):
def __init__(self, method, dbus_interface):
self.method = method
self.dbus_interface = dbus_interface
def __repr__(self):
return '<bound interface %s for %s>' % (
self.dbus_interface, self.method)
def __call__(self, *args, **kw):
kw.setdefault('dbus_interface', self.dbus_interface)
return self.method(*args, **kw)