1 files changed, 34 insertions, 0 deletions
diff --git a/lib/testtools/testtools/tags.py b/lib/testtools/testtools/tags.py
new file mode 100644
index 0000000000..b55bd38667
--- /dev/null
+++ b/lib/testtools/testtools/tags.py
@@ -0,0 +1,34 @@
+# Copyright (c) 2012 testtools developers. See LICENSE for details.
+
+"""Tag support."""
+
+
+class TagContext(object):
+    """A tag context."""
+
+    def __init__(self, parent=None):
+        """Create a new TagContext.
+
+        :param parent: If provided, uses this as the parent context.  Any tags
+            that are current on the parent at the time of construction are
+            current in this context.
+        """
+        self.parent = parent
+        self._tags = set()
+        if parent:
+            self._tags.update(parent.get_current_tags())
+
+    def get_current_tags(self):
+        """Return any current tags."""
+        return set(self._tags)
+
+    def change_tags(self, new_tags, gone_tags):
+        """Change the tags on this context.
+
+        :param new_tags: A set of tags to add to this context.
+        :param gone_tags: A set of tags to remove from this context.
+        :return: The tags now current on this context.
+        """
+        self._tags.update(new_tags)
+        self._tags.difference_update(gone_tags)
+        return self.get_current_tags()