Fix dataflow work

* Unit test

Closes-bug: #1376682

Change-Id: I6fdd6f9cc705bf016646d5bd5fcf98bec450cadb

mistral/tests/unit/engine1/test_dataflow.py

@@ -0,0 +1,87 @@
+# Copyright 2014 - Mirantis, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+
+from oslo.config import cfg
+
+from mistral.db.v2 import api as db_api
+from mistral.engine import states
+from mistral.openstack.common import log as logging
+from mistral.services import workbooks as wb_service
+from mistral.tests.unit.engine1 import base
+
+LOG = logging.getLogger(__name__)
+# Use the set_default method to set value otherwise in certain test cases
+# the change in value is not permanent.
+cfg.CONF.set_default('auth_enable', False, group='pecan')
+
+WORKBOOK = """
+---
+version: '2.0'
+name: wb
+workflows:
+  wf1:
+    type: direct
+
+    tasks:
+      task1:
+        action: std.echo output="Hi,"
+        publish:
+          hi: $
+        on-success:
+          - task2
+
+      task2:
+        action: std.echo output="Morpheus"
+        publish:
+          username: $
+        on-success:
+          - task3
+
+      task3:
+        action: std.echo output="{$.hi} {$.username}!"
+        publish:
+          result: $
+"""
+
+
+class DataFlowEngineTest(base.EngineTestCase):
+    def test_trivial_dataflow(self):
+        wb_service.create_workbook_v2({'definition': WORKBOOK})
+
+        # Start workflow.
+        exec_db = self.engine.start_workflow('wb.wf1', {})
+
+        self._await(
+            lambda: self.is_execution_success(exec_db.id),
+        )
+
+        # Note: We need to reread execution to access related tasks.
+        exec_db = db_api.get_execution(exec_db.id)
+
+        self.assertEqual(states.SUCCESS, exec_db.state)
+
+        tasks = exec_db.tasks
+        task3 = self._assert_single_item(tasks, name='task3')
+
+        self.assertEqual(states.SUCCESS, task3.state)
+
+        self.assertDictEqual(
+            {
+                'task': {
+                    'task3': 'Hi, Morpheus!',
+                },
+                'result': 'Hi, Morpheus!',
+            },
+            task3.output
+        )

mistral/workflow/data_flow.py

@@ -53,7 +53,7 @@ def prepare_db_task(task_db, task_spec, upstream_task_specs, exec_db,
         # TODO(rakhmerov): Think if Data Flow should be a part of wf handler.
         task_db.in_context = utils.merge_dicts(
             task_db.in_context,
-            copy.copy(cause_task_db.output)
+            evaluate_outbound_context(cause_task_db)
         )
 
     task_db.input = evaluate_task_input(