D-Bus testing: assertEqual for D-Bus, sortLists

unittest.assertEqual() works for standard Python to dbus type
comparisons, but the output for mismatches is very unreadable. The
custom version which is now used everywhere reduces the dbus types to
their Python counterparts, which makes the error output much more
useful (diff with Python 2.7).

Also added an optional sortLists parameter which, if true, normalizes
the lists in the values. This is necessary for D-Bus APIs which return
lists without guaranteeing a specific order of the elements.

test/test-dbus.py

@@ -1222,6 +1222,53 @@ status: idle, 0, {}
             else:
                 self.fail("'" + str(needle) + "' found in '" + str(haystack) + "'")
 
+    dbusTypeMapping = {
+        dbus.Array: list,
+        dbus.Boolean: bool,
+        dbus.Byte: int,
+        dbus.Dictionary: dict,
+        dbus.Double: float,
+        dbus.Int16: int,
+        dbus.Int32: int,
+        dbus.Int64: long,
+        dbus.ObjectPath: str,
+        dbus.Signature: str,
+        dbus.String: unicode,
+        dbus.Struct: tuple,
+        dbus.UInt16: int,
+        dbus.UInt32: int,
+        dbus.UInt64: long,
+        dbus.UTF8String: unicode
+        }
+
+    def stripDBus(self, instance, sortLists):
+        base =  DBusUtil.dbusTypeMapping.get(type(instance), None)
+        if base == dict or isinstance(instance, dict):
+            return dict([(self.stripDBus(k, sortLists), self.stripDBus(v, sortLists)) for k, v in instance.iteritems()])
+        if base == list or isinstance(instance, list):
+            l = [self.stripDBus(v, sortLists) for v in instance]
+            if sortLists:
+                l.sort()
+            return l
+        if base == tuple or isinstance(instance, tuple):
+            return tuple([self.stripDBus(v, sortLists) for v in instance])
+        if base == None:
+            return instance
+        if base == unicode:
+            # try conversion to normal string
+            try:
+                return str(instance)
+            except UnicodeEncodeError:
+                pass
+        return base(instance)
+
+    def assertEqualCustom(self, a, b, msg=None, sortLists=False):
+        '''Reduce custom dbus types to the corresponding Python type, to simplify the output in the error message.'''
+        unittest.TestCase.assertEqual(self, self.stripDBus(a, sortLists), self.stripDBus(b, sortLists), msg)
+
+    # always use our own compare
+    assertEqual = assertEqualCustom
+
     # reimplement Python 2.7 assertions only in older Python
     if True or not 'assertRegexpMatches' in dir(unittest.TestCase):
         assertRegexpMatches = assertRegexpMatchesCustom