Implement reverseOrder option for GetWorkflowExecutionHistory and PollForDecisionTask

moto/swf/models/decision_task.py

@@ -16,10 +16,11 @@ class DecisionTask(object):
         # but that shouldn't be a problem for tests
         self.scheduled_at = datetime.now()
 
-    def to_full_dict(self):
+    def to_full_dict(self, reverse_order=False):
+        events = self.workflow_execution.events(reverse_order=reverse_order)
         hsh = {
             "events": [
-                evt.to_dict() for evt in self.workflow_execution.events
+                evt.to_dict() for evt in events
             ],
             "taskToken": self.task_token,
             "previousStartedEventId": self.previous_started_event_id,

moto/swf/models/workflow_execution.py

@@ -32,7 +32,7 @@ class WorkflowExecution(object):
             "openChildWorkflowExecutions": 0,
         }
         # events
-        self.events = []
+        self._events = []
         # tasks
         self.decision_tasks = []
         self.activity_tasks = []
@@ -97,13 +97,19 @@ class WorkflowExecution(object):
         hsh["openCounts"] = self.open_counts
         return hsh
 
+    def events(self, reverse_order=False):
+        if reverse_order:
+            return reversed(self._events)
+        else:
+            return self._events
+
     def next_event_id(self):
-        event_ids = [evt.event_id for evt in self.events]
+        event_ids = [evt.event_id for evt in self._events]
         return max(event_ids or [0])
 
     def _add_event(self, *args, **kwargs):
         evt = HistoryEvent(self.next_event_id(), *args, **kwargs)
-        self.events.append(evt)
+        self._events.append(evt)
         return evt
 
     def start(self):

moto/swf/responses.py

@@ -215,22 +215,24 @@ class SWFResponse(BaseResponse):
         _workflow_execution = self._params["execution"]
         run_id = _workflow_execution["runId"]
         workflow_id = _workflow_execution["workflowId"]
-        # TODO: implement reverseOrder
+        reverse_order = self._params.get("reverseOrder", None)
-
         wfe = self.swf_backend.describe_workflow_execution(domain_name, run_id, workflow_id)
+        events = wfe.events(reverse_order=reverse_order)
         return json.dumps({
-            "events": [evt.to_dict() for evt in wfe.events]
+            "events": [evt.to_dict() for evt in events]
         })
 
     def poll_for_decision_task(self):
         domain_name = self._params["domain"]
         task_list = self._params["taskList"]["name"]
         identity = self._params.get("identity")
-        # TODO: implement reverseOrder
+        reverse_order = self._params.get("reverseOrder", None)
         decision = self.swf_backend.poll_for_decision_task(
             domain_name, task_list, identity=identity
         )
         if decision:
-            return json.dumps(decision.to_full_dict())
+            return json.dumps(
+                decision.to_full_dict(reverse_order=reverse_order)
+            )
         else:
             return json.dumps({"previousStartedEventId": 0, "startedEventId": 0})

tests/test_swf/test_decision_tasks.py

@@ -44,3 +44,10 @@ def test_poll_for_decision_task_when_none():
     # this is the DecisionTask representation you get from the real SWF
     # after waiting 60s when there's no decision to be taken
     resp.should.equal({"previousStartedEventId": 0, "startedEventId": 0})
+
+@mock_swf
+def test_poll_for_decision_task_with_reverse_order():
+    conn = setup_workflow()
+    resp = conn.poll_for_decision_task("test-domain", "queue", reverse_order=True)
+    types = [evt["eventType"] for evt in resp["events"]]
+    types.should.equal(["DecisionTaskStarted", "DecisionTaskScheduled", "WorkflowExecutionStarted"])

tests/test_swf/test_models.py

@@ -197,8 +197,8 @@ def test_workflow_execution_start_decision_task():
     wfe.start_decision_task(dt.task_token, identity="srv01")
     dt = wfe.decision_tasks[0]
     dt.state.should.equal("STARTED")
-    wfe.events[-1].event_type.should.equal("DecisionTaskStarted")
+    wfe.events()[-1].event_type.should.equal("DecisionTaskStarted")
-    wfe.events[-1].identity.should.equal("srv01")
+    wfe.events()[-1].identity.should.equal("srv01")
 
 
 # HistoryEvent

tests/test_swf/test_workflow_executions.py

@@ -79,10 +79,19 @@ def test_get_workflow_execution_history():
     run_id = hsh["runId"]
 
     resp = conn.get_workflow_execution_history("test-domain", run_id, "uid-abcd1234")
-    resp["events"].should.be.a("list")
+    types = [evt["eventType"] for evt in resp["events"]]
-    evt = resp["events"][0]
+    types.should.equal(["WorkflowExecutionStarted", "DecisionTaskScheduled"])
-    evt["eventType"].should.equal("WorkflowExecutionStarted")
 
+@mock_swf
+def test_get_workflow_execution_history_with_reverse_order():
+    conn = setup_swf_environment()
+    hsh = conn.start_workflow_execution("test-domain", "uid-abcd1234", "test-workflow", "v1.0")
+    run_id = hsh["runId"]
+
+    resp = conn.get_workflow_execution_history("test-domain", run_id, "uid-abcd1234",
+                                               reverse_order=True)
+    types = [evt["eventType"] for evt in resp["events"]]
+    types.should.equal(["DecisionTaskScheduled", "WorkflowExecutionStarted"])
 
 @mock_swf
 def test_get_workflow_execution_history_on_non_existent_workflow_execution():