#NEWLINE# def test_graph_flow_link_raises_on_link_cycle( self ) : #NEWLINE# #INDENT# task1 = _task ( 'task1' ) #NEWLINE# task2 = _task ( 'task2' ) #NEWLINE# f = gf . Flow ( 'test' ) . add ( task1 , task2 ) #NEWLINE# f . link ( task1 , task2 ) #NEWLINE# self . assertRaises ( exc . DependencyFailure , f . link , task2 , task1 )