def test_add_tag_doesnt_duplicate(self):
block_device = BlockDevice()
tag = factory.make_name('tag')
block_device.add_tag(tag)
block_device.add_tag(tag)
self.assertItemsEqual([tag], block_device.tags)
def test_remove_tag_deletes_tag(self):
block_device = BlockDevice()
tag = factory.make_name('tag')
block_device.add_tag(tag)
block_device.remove_tag(tag)
self.assertItemsEqual([], block_device.tags)
def test_add_tag_adds_new_tag(self):
block_device = BlockDevice()
tag = factory.make_name('tag')
block_device.add_tag(tag)
self.assertItemsEqual([tag], block_device.tags)
