Merge lp:~veebers/autopilot/1.4_fixing_backend_being_none into lp:autopilot

[Christopher Lee]

Fixes issue where a classes _Backend can be None causes uncaught exceptions.

Fixes issue where a classes _Backend can be None causes uncaught exceptions.
The backend is now stored as an instance variable.

Forward port of: https://code.launchpad.net/~veebers/autopilot/fixing_backend_being_none/+merge/188762

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[Thomi Richards (thomir-deactivatedaccount)]

LGTM

review: Approve

[Thomi Richards (thomir-deactivatedaccount)]

LGTM.

review: Approve

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review: Needs Fixing (continuous-integration)

[lp:~veebers/autopilot/1.4_fixing_backend_being_none]

349. By Christopher Lee on 2013-10-09

Added porting notes.

350. By Christopher Lee on 2013-10-09

Fixed the documentation

351. By Christopher Lee on 2013-10-09

Merge trunk

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=== modified file 'autopilot/introspection/__init__.py'
--- autopilot/introspection/__init__.py	2013-09-29 22:45:15 +0000
+++ autopilot/introspection/__init__.py	2013-10-09 23:03:58 +0000
@@ -43,7 +43,6 @@
     AP_INTROSPECTION_IFACE,
 )
 from autopilot.introspection.dbus import (
-    _clear_backends_for_proxy_object,
     CustomEmulatorBase,
     DBusIntrospectionObject,
     get_classname_from_path,
@@ -485,16 +484,17 @@
     proxy_bases = proxy_bases + (emulator_base, )
     cls_name, cls_state = _get_proxy_object_class_name_and_state(data_source)
 
-    _clear_backends_for_proxy_object(emulator_base)
-    clsobj = type(
-        # Merge the object hierarchy.
-        str("%sBase" % cls_name), proxy_bases, dict(_Backend=data_source)
-    )
+    # Merge the object hierarchy.
+    clsobj = type(str("%sBase" % cls_name), proxy_bases, {})
 
     proxy_class = type(str(cls_name), (clsobj,), {})
 
-    proxy = proxy_class.get_root_instance()
-    return proxy
+    try:
+        dbus_tuple = data_source.introspection_iface.GetState("/")[0]
+        path, state = dbus_tuple
+        return proxy_class(state, path, data_source)
+    except IndexError:
+        raise RuntimeError("Unable to find root object of %r" % proxy_class)
 
 
 def _get_proxy_object_base_classes(backend):
@@ -529,8 +529,8 @@
 class ApplicationProxyObject(DBusIntrospectionObject):
     """A class that better supports query data from an application."""
 
-    def __init__(self, state, path):
-        super(ApplicationProxyObject, self).__init__(state, path)
+    def __init__(self, state, path, backend):
+        super(ApplicationProxyObject, self).__init__(state, path, backend)
         self._process = None
 
     def set_process(self, process):
 
=== modified file 'autopilot/introspection/dbus.py'
--- autopilot/introspection/dbus.py	2013-09-29 22:45:15 +0000
+++ autopilot/introspection/dbus.py	2013-10-09 23:03:58 +0000
@@ -126,20 +126,6 @@
         return class_object
 
 
-def _clear_backends_for_proxy_object(proxy_object):
-    """Iterate over the object registry and clear the dbus backend address set
-    on any class that has the same id as the specified proxy_object.
-
-    This is required so consecutive tests do not end up re-using the same dbus
-    backend address as a previous run, which will probably be incorrect.
-
-    """
-    global _object_registry
-    for cls in _object_registry[proxy_object._id].values():
-        if type(proxy_object) is not cls:
-            cls._Backend = None
-
-
 def get_classname_from_path(object_path):
     return object_path.split("/")[-1]
 
@@ -174,14 +160,13 @@
 
     """
 
-    _Backend = None
-
-    def __init__(self, state_dict, path):
+    def __init__(self, state_dict, path, backend):
         self.__state = {}
         self.__refresh_on_attribute = True
         self._set_properties(state_dict)
         self._path = path
         self._poll_time = 10
+        self._backend = backend
 
     def _set_properties(self, state_dict):
         """Creates and set attributes of *self* based on contents of
@@ -484,8 +469,7 @@
         _, new_state = self.get_new_state()
         self._set_properties(new_state)
 
-    @classmethod
-    def get_all_instances(cls):
+    def get_all_instances(self):
         """Get all instances of this class that exist within the Application
         state tree.
 
@@ -503,23 +487,22 @@
         :return: List (possibly empty) of class instances.
 
         """
-        cls_name = cls.__name__
-        instances = cls.get_state_by_path("//%s" % (cls_name))
-        return [cls.make_introspection_object(i) for i in instances]
+        cls_name = type(self).__name__
+        instances = self.get_state_by_path("//%s" % (cls_name))
+        return [self.make_introspection_object(i) for i in instances]
 
-    @classmethod
-    def get_root_instance(cls):
+    def get_root_instance(self):
         """Get the object at the root of this tree.
 
         This will return an object that represents the root of the
         introspection tree.
 
         """
-        instances = cls.get_state_by_path("/")
+        instances = self.get_state_by_path("/")
         if len(instances) != 1:
             logger.error("Could not retrieve root object.")
             return None
-        return cls.make_introspection_object(instances[0])
+        return self.make_introspection_object(instances[0])
 
     def __getattr__(self, name):
         # avoid recursion if for some reason we have no state set (should never
@@ -536,8 +519,7 @@
             "Class '%s' has no attribute '%s'." %
             (self.__class__.__name__, name))
 
-    @classmethod
-    def get_state_by_path(cls, piece):
+    def get_state_by_path(self, piece):
         """Get state for a particular piece of the state tree.
 
         You should probably never need to call this directly.
@@ -552,7 +534,7 @@
                 "XPath query must be a string, not %r", type(piece))
 
         with Timer("GetState %s" % piece):
-            data = cls._Backend.introspection_iface.GetState(piece)
+            data = self._backend.introspection_iface.GetState(piece)
             if len(data) > 15:
                 logger.warning(
                     "Your query '%s' returned a lot of data (%d items). This "
@@ -584,8 +566,7 @@
         else:
             return self._path + "[id=%d]" % self.id
 
-    @classmethod
-    def make_introspection_object(cls, dbus_tuple):
+    def make_introspection_object(self, dbus_tuple):
         """Make an introspection object given a DBus tuple of
         (path, state_dict).
 
@@ -594,23 +575,21 @@
         path, state = dbus_tuple
         name = get_classname_from_path(path)
         try:
-            class_type = _object_registry[cls._id][name]
-            if class_type._Backend is None:
-                class_type._Backend = cls._Backend
+            class_type = _object_registry[self._id][name]
         except KeyError:
             get_debug_logger().warning(
                 "Generating introspection instance for type '%s' based on "
                 "generic class.", name)
             # we want the object to inherit from the custom emulator base, not
             # the object class that is doing the selecting
-            for base in cls.__bases__:
+            for base in type(self).__bases__:
                 if issubclass(base, CustomEmulatorBase):
                     base_class = base
                     break
             else:
-                base_class = cls
+                base_class = type(self)
             class_type = type(str(name), (base_class,), {})
-        return class_type(state, path)
+        return class_type(state, path, self._backend)
 
     @contextmanager
     def no_automatic_refreshing(self):
 
=== modified file 'autopilot/introspection/qt.py'
--- autopilot/introspection/qt.py	2013-09-18 23:14:02 +0000
+++ autopilot/introspection/qt.py	2013-10-09 23:03:58 +0000
@@ -100,7 +100,7 @@
 
         """
 
-        return self._Backend.qt_introspection_iface
+        return self._backend.qt_introspection_iface
 
     @property
     def slots(self):
 
=== modified file 'autopilot/tests/unit/test_introspection_features.py'
--- autopilot/tests/unit/test_introspection_features.py	2013-09-27 05:55:31 +0000
+++ autopilot/tests/unit/test_introspection_features.py	2013-10-09 23:03:58 +0000
@@ -18,7 +18,7 @@
 #
 
 
-from mock import patch
+from mock import patch, Mock
 from testtools import TestCase
 from testtools.matchers import Equals, NotEquals
 from testscenarios import TestWithScenarios
@@ -120,7 +120,8 @@
     def test_can_access_path_attribute(self):
         fake_object = DBusIntrospectionObject(
             dict(id=[0, 123], path=[0, '/some/path']),
-            '/'
+            '/',
+            Mock()
         )
         with fake_object.no_automatic_refreshing():
             self.assertThat(fake_object.path, Equals('/some/path'))
@@ -132,10 +133,14 @@
         'large' is defined as more than 15.
 
         """
-        with patch.object(DBusIntrospectionObject, '_Backend') as p:
-            p.introspection_iface.GetState.return_value = \
-                [('/path', {}) for i in range(16)]
-            DBusIntrospectionObject.get_state_by_path('some_query')
+        fake_object = DBusIntrospectionObject(
+            dict(id=[0, 123], path=[0, '/some/path']),
+            '/',
+            Mock()
+        )
+        fake_object._backend.introspection_iface.GetState.return_value = \
+            [('/path', {}) for i in range(16)]
+        fake_object.get_state_by_path('some_query')
 
         mock_logger.warning.assert_called_once_with(
             "Your query '%s' returned a lot of data (%d items). This "
@@ -151,9 +156,13 @@
         'small' is defined as 15 or fewer.
 
         """
-        with patch.object(DBusIntrospectionObject, '_Backend') as p:
-            p.introspection_iface.GetState.return_value = \
-                [('/path', {}) for i in range(15)]
-            DBusIntrospectionObject.get_state_by_path('some_query')
+        fake_object = DBusIntrospectionObject(
+            dict(id=[0, 123], path=[0, '/some/path']),
+            '/',
+            Mock()
+        )
+        fake_object._backend.introspection_iface.GetState.return_value = \
+            [('/path', {}) for i in range(15)]
+        fake_object.get_state_by_path('some_query')
 
         self.assertThat(mock_logger.warning.called, Equals(False))
 
=== modified file 'autopilot/tests/unit/test_matchers.py'
--- autopilot/tests/unit/test_matchers.py	2013-09-16 17:17:35 +0000
+++ autopilot/tests/unit/test_matchers.py	2013-10-09 23:03:58 +0000
@@ -66,7 +66,7 @@
     """
     class FakeObject(DBusIntrospectionObject):
         def __init__(self, props):
-            super(FakeObject, self).__init__(props, "/FakeObject")
+            super(FakeObject, self).__init__(props, "/FakeObject", None)
             FakeObject._fake_props = props
 
         @classmethod
 
=== modified file 'autopilot/tests/unit/test_types.py'
--- autopilot/tests/unit/test_types.py	2013-09-26 23:34:52 +0000
+++ autopilot/tests/unit/test_types.py	2013-10-09 23:03:58 +0000
@@ -20,7 +20,7 @@
 from __future__ import absolute_import
 
 from datetime import datetime, time
-from mock import patch
+from mock import patch, Mock
 from testscenarios import TestWithScenarios
 from testtools import TestCase
 from testtools.matchers import Equals, IsInstance, NotEquals, raises
@@ -636,7 +636,8 @@
         """
         DBusIntrospectionObject(
             dict(foo=[0]),
-            '/some/dummy/path'
+            '/some/dummy/path',
+            Mock()
         )
         error_logger.assert_called_once_with(
             "While constructing attribute '%s.%s': %s",
 
=== modified file 'docs/porting/porting.rst'
--- docs/porting/porting.rst	2013-09-26 22:54:34 +0000
+++ docs/porting/porting.rst	2013-10-09 23:03:58 +0000
@@ -51,6 +51,30 @@
 
 	my_obj = self.app.wait_select_single("MyObject")
 
+.. _dbus_backends:
+
+DBus backends and :class:`~autopilot.introspection.dbus.DBusIntrospectionObject` changes
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+Due to a change in how
+:class:`~autopilot.introspection.dbus.DBusIntrospectionObject` objects store
+their DBus backend a couple of classmethods have now become instance methods.
+
+These affected methods are:
+
+ * :meth:`~autopilot.introspection.dbus.DBusIntrospectionObject.get_all_instances`
+ * :meth:`~autopilot.introspection.dbus.DBusIntrospectionObject.get_root_instance`
+ * :meth:`~autopilot.introspection.dbus.DBusIntrospectionObject.get_state_by_path`
+
+For example, if your old code is something along the lines of::
+
+    all_keys = KeyCustomEmulator.get_all_instances()
+
+You will instead need to have something like this instead::
+
+    all_keys = app_proxy.select_many(KeyCustomEmulator)
+
+
 Python 3
 ++++++++
 
@@ -70,6 +94,10 @@
 * A large code cleanup and reorganisation. In particular, lots of code that came from the Unity 3D codebase has been removed if it was deemed to not be useful to the majority of test authors. This code cleanup includes a flattening of the autopilot namespace. Previously, many useful classes lived under the ``autopilot.emulators`` namespace. These have now been moved into the ``autopilot`` namespace.
 
 
+.. note:: There is an API breakage in autopilot 1.3. The changes outlined under
+          the heading ":ref:`dbus_backends`" apply to version
+          1.3.1+13.10.20131003.1-0ubuntu1 and onwards .
+
 ``QtIntrospectionTestMixin`` and ``GtkIntrospectionTestMixin`` no longer exist
 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++