Correct issues with slices and some more subtle bugs.

jedi/evaluate/analysis.py

@@ -184,7 +184,7 @@ def _check_for_exception_catch(evaluator, jedi_obj, exception, payload=None):
             # Check name
             key, values = args[1]
             assert len(values) == 1
-            names = evaluator.eval_element(values[0])
+            names = list(evaluator.eval_element(values[0]))
             assert len(names) == 1 and isinstance(names[0], CompiledObject)
             assert names[0].obj == str(payload[1])
 

jedi/evaluate/iterable.py

@@ -634,11 +634,11 @@ class Slice(object):
 
             result = self._evaluator.eval_element(element)
             if len(result) != 1:
-                # We want slices to be clear defined with just one type.
-                # Otherwise we will return an empty slice object.
+                # For simplicity, we want slices to be clear defined with just
+                # one type.  Otherwise we will return an empty slice object.
                 raise IndexError
             try:
-                return result[0].obj
+                return list(result)[0].obj
             except AttributeError:
                 return None
 

jedi/evaluate/stdlib.py

@@ -238,7 +238,7 @@ def collections_namedtuple(evaluator, obj, arguments):
 
     # Parse source
     generated_class = Parser(evaluator.grammar, unicode(source)).module.subscopes[0]
-    return set(er.Class(evaluator, generated_class))
+    return set([er.Class(evaluator, generated_class)])
 
 
 @argument_clinic('first, /')