lib/testtools/testtools/tags.py

   1 # Copyright (c) 2012 testtools developers. See LICENSE for details.
   2
   3 """Tag support."""
   4
   5
   6 class TagContext(object):
   7     """A tag context."""
   8
   9     def __init__(self, parent=None):
  10         """Create a new TagContext.
  11
  12         :param parent: If provided, uses this as the parent context.  Any tags
  13             that are current on the parent at the time of construction are
  14             current in this context.
  15         """
  16         self.parent = parent
  17         self._tags = set()
  18         if parent:
  19             self._tags.update(parent.get_current_tags())
  20
  21     def get_current_tags(self):
  22         """Return any current tags."""
  23         return set(self._tags)
  24
  25     def change_tags(self, new_tags, gone_tags):
  26         """Change the tags on this context.
  27
  28         :param new_tags: A set of tags to add to this context.
  29         :param gone_tags: A set of tags to remove from this context.
  30         :return: The tags now current on this context.
  31         """
  32         self._tags.update(new_tags)
  33         self._tags.difference_update(gone_tags)
  34         return self.get_current_tags()