'Disable a single plugin.'

def test_disable(self):

    p = PluginManager(None)
    events = []
    def init(self):
        events.append('init')
    def end(self):
        events.append('end')
    A.plugin_init = init
    A.plugin_end = end
    p.enable('a')
    p.disable('a')
    self.assertEqual(len(p), 0, 'Wrong    number    of    enabled    plugins.')
    self.assertEqual(events, ['init', 'end'], 'Plugin    lifecycle    methods    not    called.')
