#NEWLINE# def test_broken_collection_assertion( self ) : #NEWLINE# #INDENT# ( A , B ) = self . _broken_collection_fixture ( ) #NEWLINE# b1 = B ( ) #NEWLINE# a1 = A ( ) #NEWLINE# assert_raises_message ( ValueError , 'Bidirectional attribute conflict detected: Passing object <A at .*> to attribute "B.a2" triggers a modify event on attribute "B.a1" via the backref "A.b".' , b1 . a2 . append , a1 )