work in progress: working on nodes lifecycle.

tests/execution/contexts/test_execution_contexts_graph.py

@@ -1,4 +1,5 @@
 from bonobo import Graph
+from bonobo.constants import EMPTY, BEGIN, END
 from bonobo.execution.contexts import GraphExecutionContext
 
 
@@ -49,9 +50,8 @@ def test_lifecycle_of_graph_with_recoverable_error():
 def test_lifecycle_of_graph_with_unrecoverable_error():
     graph = Graph([1, 2, 3], raise_an_unrecoverrable_error, print)
     with GraphExecutionContext(graph) as context:
-        assert context.started
-        assert context.alive
-        assert not context.stopped
+        assert context.started and context.alive and not context.stopped
+        context.write(BEGIN, EMPTY, END)
         context.loop()
     assert context.started
     assert not context.alive