diff --git a/bitbake/lib/bb/tests/cow.py b/bitbake/lib/bb/tests/cow.py
new file mode 100644
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+++ b/bitbake/lib/bb/tests/cow.py
@@ -0,0 +1,136 @@
+# ex:ts=4:sw=4:sts=4:et
+# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#
+# BitBake Tests for Copy-on-Write (cow.py)
+#
+# Copyright 2006 Holger Freyther <freyther@handhelds.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# 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.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+
+import unittest
+import os
+
+class COWTestCase(unittest.TestCase):
+    """
+    Test case for the COW module from mithro
+    """
+
+    def testGetSet(self):
+        """
+        Test and set
+        """
+        from bb.COW import COWDictBase
+        a = COWDictBase.copy()
+
+        self.assertEquals(False, a.has_key('a'))
+
+        a['a'] = 'a'
+        a['b'] = 'b'
+        self.assertEquals(True, a.has_key('a'))
+        self.assertEquals(True, a.has_key('b'))
+        self.assertEquals('a', a['a'] )
+        self.assertEquals('b', a['b'] )
+
+    def testCopyCopy(self):
+        """
+        Test the copy of copies
+        """
+
+        from bb.COW import COWDictBase
+
+        # create two COW dict 'instances'
+        b = COWDictBase.copy()
+        c = COWDictBase.copy()
+
+        # assign some keys to one instance, some keys to another
+        b['a'] = 10
+        b['c'] = 20
+        c['a'] = 30
+
+        # test separation of the two instances
+        self.assertEquals(False, c.has_key('c'))
+        self.assertEquals(30, c['a'])
+        self.assertEquals(10, b['a'])
+
+        # test copy
+        b_2 = b.copy()
+        c_2 = c.copy()
+
+        self.assertEquals(False, c_2.has_key('c'))
+        self.assertEquals(10, b_2['a'])
+
+        b_2['d'] = 40
+        self.assertEquals(False, c_2.has_key('d'))
+        self.assertEquals(True, b_2.has_key('d'))
+        self.assertEquals(40, b_2['d'])
+        self.assertEquals(False, b.has_key('d'))
+        self.assertEquals(False, c.has_key('d'))
+
+        c_2['d'] = 30
+        self.assertEquals(True, c_2.has_key('d'))
+        self.assertEquals(True, b_2.has_key('d'))
+        self.assertEquals(30, c_2['d'])
+        self.assertEquals(40, b_2['d'])
+        self.assertEquals(False, b.has_key('d'))
+        self.assertEquals(False, c.has_key('d'))
+
+        # test copy of the copy
+        c_3 = c_2.copy()
+        b_3 = b_2.copy()
+        b_3_2 = b_2.copy()
+
+        c_3['e'] = 4711
+        self.assertEquals(4711, c_3['e'])
+        self.assertEquals(False, c_2.has_key('e'))
+        self.assertEquals(False, b_3.has_key('e'))
+        self.assertEquals(False, b_3_2.has_key('e'))
+        self.assertEquals(False, b_2.has_key('e'))
+
+        b_3['e'] = 'viel'
+        self.assertEquals('viel', b_3['e'])
+        self.assertEquals(4711, c_3['e'])
+        self.assertEquals(False, c_2.has_key('e'))
+        self.assertEquals(True, b_3.has_key('e'))
+        self.assertEquals(False, b_3_2.has_key('e'))
+        self.assertEquals(False, b_2.has_key('e'))
+
+    def testCow(self):
+        from bb.COW import COWDictBase
+        c = COWDictBase.copy()
+        c['123'] = 1027
+        c['other'] = 4711
+        c['d'] = { 'abc' : 10, 'bcd' : 20 }
+
+        copy = c.copy()
+
+        self.assertEquals(1027, c['123'])
+        self.assertEquals(4711, c['other'])
+        self.assertEquals({'abc':10, 'bcd':20}, c['d'])
+        self.assertEquals(1027, copy['123'])
+        self.assertEquals(4711, copy['other'])
+        self.assertEquals({'abc':10, 'bcd':20}, copy['d'])
+
+        # cow it now
+        copy['123'] = 1028
+        copy['other'] = 4712
+        copy['d']['abc'] = 20
+
+
+        self.assertEquals(1027, c['123'])
+        self.assertEquals(4711, c['other'])
+        self.assertEquals({'abc':10, 'bcd':20}, c['d'])
+        self.assertEquals(1028, copy['123'])
+        self.assertEquals(4712, copy['other'])
+        self.assertEquals({'abc':20, 'bcd':20}, copy['d'])