34: Added tests.unit_common with frequently used utility functions; split ro __setattr__, __delattr__ methods out of Proxy and into new ReadOnly base class; added corresponding unit tests

ipalib/plugable.py

@@ -67,7 +67,32 @@ class Plugin(object):
 		)
 
 
-class Proxy(object):
+class ReadOnly(object):
+	"""
+	Base class for classes with read-only attributes.
+	"""
+	__slots__ = tuple()
+
+	def __setattr__(self, name, value):
+		"""
+		This raises an AttributeError anytime an attempt is made to set an
+		attribute.
+		"""
+		raise AttributeError('read-only: cannot set %s.%s' %
+			(self.__class__.__name__, name)
+		)
+
+	def __delattr__(self, name):
+		"""
+		This raises an AttributeError anytime an attempt is made to delete an
+		attribute.
+		"""
+		raise AttributeError('read-only: cannot del %s.%s' %
+			(self.__class__.__name__, name)
+		)
+
+
+class Proxy(ReadOnly):
 	"""
 	Used to only export certain attributes into the dynamic API.
 
@@ -92,24 +117,6 @@ class Proxy(object):
 		for name in self.__slots__:
 			object.__setattr__(self, name, getattr(obj, name))
 
-	def __setattr__(self, name, value):
-		"""
-		Proxy instances are read-only.  This raises an AttributeError
-		anytime an attempt is made to set an attribute.
-		"""
-		raise AttributeError('cannot set %s.%s' %
-			(self.__class__.__name__, name)
-		)
-
-	def __delattr__(self, name):
-		"""
-		Proxy instances are read-only.  This raises an AttributeError
-		anytime an attempt is made to delete an attribute.
-		"""
-		raise AttributeError('cannot del %s.%s' %
-			(self.__class__.__name__, name)
-		)
-
 	def __repr__(self):
 		return '%s(%r)' % (self.__class__.__name__, self.__obj)
 

ipalib/tests/test_plugable.py

@@ -21,6 +21,7 @@
 Unit tests for `ipalib.plugable` module.
 """
 
+import unit_common as uc
 from ipalib import plugable, errors
 
 
@@ -52,6 +53,23 @@ def test_Plugin():
 	assert repr(p) == '%s.some_plugin()' % __name__
 
 
+def test_ReadOnly():
+	obj = plugable.ReadOnly()
+	names = ['not_an_attribute', 'an_attribute']
+	for name in names:
+		uc.no_set(obj, name)
+		uc.no_del(obj, name)
+
+	class some_ro_class(plugable.ReadOnly):
+		def __init__(self):
+			object.__setattr__(self, 'an_attribute', 'Hello world!')
+	obj = some_ro_class()
+	for name in names:
+		uc.no_set(obj, name)
+		uc.no_del(obj, name)
+	assert uc.read_only(obj, 'an_attribute') == 'Hello world!'
+
+
 def test_Proxy():
 	class CommandProxy(plugable.Proxy):
 		__slots__ = (

ipalib/tests/unit_common.py

@@ -0,0 +1,63 @@
+# Authors:
+#   Jason Gerard DeRose <jderose@redhat.com>
+#
+# Copyright (C) 2008  Red Hat
+# see file 'COPYING' for use and warranty information
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation; version 2 only
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+"""
+Utility functions for unit tests.
+"""
+
+
+def no_set(obj, name):
+	"""
+	Tests that attribute cannot be set.
+	"""
+	raised = False
+	try:
+		setattr(obj, name, 'some_new_obj')
+	except AttributeError:
+		raised = True
+	assert raised
+
+
+def no_del(obj, name):
+	"""
+	Tests that attribute cannot be deleted.
+	"""
+	raised = False
+	try:
+		delattr(obj, name)
+	except AttributeError:
+		raised = True
+	assert raised
+
+
+def read_only(obj, name):
+	"""
+	Tests that attribute is read-only. Returns attribute.
+	"""
+	assert isinstance(obj, object)
+	assert hasattr(obj, name)
+
+	# Test that it cannot be set:
+	no_set(obj, name)
+
+	# Test that it cannot be deleted:
+	no_del(obj, name)
+
+	# Return the attribute
+	return getattr(obj, name)