First tests are now passing.

jedi/common/context.py

@@ -19,7 +19,6 @@ class ContextSet(object):
         """
         aggregated = set()
         for set_ in sets:
-            print(set_)
             if isinstance(set_, ContextSet):
                 aggregated |= set_._set
             else:
@@ -33,6 +32,9 @@ class ContextSet(object):
         for element in self._set:
             yield element
 
+    def __bool__(self):
+        return bool(self._set)
+
     def __repr__(self):
         return '%s(%s)' % (self.__class__.__name__, ', '.join(str(s) for s in self._set))
 

jedi/evaluate/filters.py

@@ -7,6 +7,7 @@ from abc import abstractmethod
 from parso.tree import search_ancestor
 from jedi.evaluate import flow_analysis
 from jedi.evaluate.utils import to_list, unite
+from jedi.common import ContextSet
 from jedi.parser_utils import get_parent_scope
 
 
@@ -64,7 +65,7 @@ class AbstractTreeName(AbstractNameDefinition):
 
 class ContextNameMixin(object):
     def infer(self):
-        return set([self._context])
+        return ContextSet(self._context)
 
     def get_root_context(self):
         if self.parent_context is None:
@@ -128,7 +129,7 @@ class AnonymousInstanceParamName(ParamName):
         if param_node.position_index == 0:
             # This is a speed optimization, to return the self param (because
             # it's known). This only affects anonymous instances.
-            return set([self.parent_context.instance])
+            return ContextSet(self.parent_context.instance)
         else:
             return self.get_param().infer()