def update(self): writer = TerminalWriter(StringIO()) progressbar = ProgressBar([], writer, maxsteps=20) widget = PercentageWidget() widget.init(progressbar, writer.get_width()) for i in xrange(5, 96, 5): progressbar.step += 1 result = widget.update(progressbar, writer.get_width()) Assert(result) == '%i%%' % i