Ensure that the engine finishes up even under sent-in failures

Change-Id: Ic16c854d285398c688f132697c3bb7e637feb9a8

taskflow/engines/action_engine/engine.py

@@ -277,6 +277,13 @@ class ActionEngine(base.Engine):
                         # shop...
                         closed = True
                         self.suspend()
+                    except Exception:
+                        # Capture the failure, and ensure that the
+                        # machine will notice that something externally
+                        # has sent an exception in and that it should
+                        # finish up and reraise.
+                        memory.failures.append(failure.Failure())
+                        closed = True
                     else:
                         if try_suspend:
                             self.suspend()

taskflow/tests/unit/test_engines.py

@@ -301,6 +301,36 @@ class EngineLinearFlowTest(utils.EngineTestBase):
         results = engine.storage.fetch_all()
         self.assertEqual(2, results['result'])
 
+    def test_sequential_flow_interrupted_externally(self):
+        flow = lf.Flow('flow-1').add(
+            utils.ProgressingTask(name='task1'),
+            utils.ProgressingTask(name='task2'),
+            utils.ProgressingTask(name='task3'),
+        )
+        engine = self._make_engine(flow)
+
+        def _run_engine_and_raise():
+            engine_states = {}
+            engine_it = engine.run_iter()
+            while True:
+                try:
+                    engine_state = six.next(engine_it)
+                    if engine_state not in engine_states:
+                        engine_states[engine_state] = 1
+                    else:
+                        engine_states[engine_state] += 1
+                    if engine_states.get(states.SCHEDULING) == 2:
+                        engine_state = engine_it.throw(IOError("I Broke"))
+                        if engine_state not in engine_states:
+                            engine_states[engine_state] = 1
+                        else:
+                            engine_states[engine_state] += 1
+                except StopIteration:
+                    break
+
+        self.assertRaises(IOError, _run_engine_and_raise)
+        self.assertEqual(states.FAILURE, engine.storage.get_flow_state())
+
     def test_sequential_flow_one_task(self):
         flow = lf.Flow('flow-1').add(
             utils.ProgressingTask(name='task1')