Fix two issues with dragonfly's mocked actions

- Make each mocked action refer to a class instead.
- Replace mock_dyn_str_action with a mocked Mouse class, as that
  action is the only DynStrActionBase sub-class left that isn't
  implemented for other platforms.

dragonfly/os_dependent_mock.py

@@ -20,26 +20,32 @@
 Heavily modified to allow more dragonfly functionality to work
 regardless of operating system.
 """
+
 from .actions import ActionBase, DynStrActionBase
 
 
-# Mock ActionBase and DynStrActionBase classes
+class MockBase(object):
+    def __init__(self, *args, **kwargs):
+        pass
+
 
-def mock_action(*args, **kwargs):
-    return ActionBase()
+class MockAction(ActionBase):
+    """ Mock class for dragonfly actions. """
+    def __init__(self, *args, **kwargs):
+        ActionBase.__init__(self)
 
 
-def mock_dyn_str_action(*args, **kwargs):
-    return DynStrActionBase(*args, **kwargs)
+class Mouse(DynStrActionBase):
+    """ Mock Mouse action class. """
+    def __init__(self, spec=None, static=False):
+        DynStrActionBase.__init__(self, spec, static)
 
 
-Paste = mock_dyn_str_action
-Mouse = mock_dyn_str_action
-WaitWindow = mock_action
-FocusWindow = mock_action
-StartApp = mock_action
-BringApp = mock_action
-PlaySound = mock_action
+WaitWindow = MockAction
+FocusWindow = MockAction
+StartApp = MockAction
+BringApp = MockAction
+PlaySound = MockAction
 
 
 class _WindowInfo(object):
@@ -54,11 +60,6 @@ def get_foreground():
         return _WindowInfo
 
 
-class MockBase(object):
-    def __init__(self, *args, **kwargs):
-        pass
-
-
 class HardwareInput(MockBase):
     pass