254: Added public.Application base class; added corresponding unit tests

ipalib/public.py

@@ -380,3 +380,42 @@ class Property(Attribute):
                 attr = getattr(self, name)
                 if is_rule(attr):
                     yield attr
+
+
+class Application(Command):
+    """
+    Base class for commands register by an external application.
+
+    Special commands that only apply to a particular application built atop
+    `ipalib` should subclass from ``Application``.
+
+    Because ``Application`` subclasses from `Command', plugins that subclass
+    from ``Application`` with be available in both the ``api.Command`` and
+    ``api.Application`` namespaces.
+    """
+
+    __public__ = frozenset((
+        'application',
+    )).union(Command.__public__)
+    __application = None
+
+    def __get_application(self):
+        """
+        Returns external ``application`` object.
+        """
+        return self.__application
+    def __set_application(self, application):
+        """
+        Sets the external application object to ``application``.
+        """
+        if self.__application is not None:
+            raise AttributeError(
+                '%s.application can only be set once' % self.name
+            )
+        if application is None:
+            raise TypeError(
+                '%s.application cannot be None' % self.name
+            )
+        object.__setattr__(self, '_Application__application', application)
+        assert self.application is application
+    application = property(__get_application, __set_application)

ipalib/tests/test_public.py

@@ -690,3 +690,36 @@ class test_Property(ClassChecker):
         assert isinstance(opt, public.Option)
         assert opt.name == 'givenname'
         assert opt.doc == 'User first name'
+
+
+class test_Application(ClassChecker):
+    """
+    Tests the `public.Application` class.
+    """
+    _cls = public.Application
+
+    def test_class(self):
+        assert self.cls.__bases__ == (public.Command,)
+        assert type(self.cls.application) is property
+
+    def test_application(self):
+        """
+        Tests the `public.Application.application` property.
+        """
+        assert 'application' in self.cls.__public__ # Public
+        app = 'The external application'
+        class example(self.cls):
+            'A subclass'
+        for o in (self.cls(), example()):
+            assert o.application is None
+            e = raises(TypeError, setattr, o, 'application', None)
+            assert str(e) == (
+                '%s.application cannot be None' % o.__class__.__name__
+            )
+            o.application = app
+            assert o.application is app
+            e = raises(AttributeError, setattr, o, 'application', app)
+            assert str(e) == (
+                '%s.application can only be set once' % o.__class__.__name__
+            )
+            assert o.application is app