Serialize False as a return value for orchestrators (#159)

* serialize falses

* added test to prevent regression

Author: davidmrdavid

azure/durable_functions/models/OrchestratorState.py

@@ -77,7 +77,7 @@ def to_json(self) -> Dict[str, Any]:
         json_dict = {}
         add_attrib(json_dict, self, '_is_done', 'isDone')
         self._add_actions(json_dict)
-        if self._output:
+        if not (self._output is None):
             json_dict['output'] = self._output
         if self._error:
             json_dict['error'] = self._error

tests/orchestrator/test_serialization.py

@@ -0,0 +1,30 @@
+from tests.test_utils.ContextBuilder import ContextBuilder
+from .orchestrator_test_utils \
+    import get_orchestration_state_result, assert_orchestration_state_equals, assert_valid_schema
+from azure.durable_functions.models.OrchestratorState import OrchestratorState
+
+def base_expected_state(output=None) -> OrchestratorState:
+    return OrchestratorState(is_done=False, actions=[], output=output)
+
+def generator_function(context):
+    return False
+
+def test_serialization_of_False():
+    """Test that an orchestrator can return False."""
+
+    context_builder = ContextBuilder("serialize False")
+
+    result = get_orchestration_state_result(
+        context_builder, generator_function)
+
+    expected_state = base_expected_state(output=False)
+
+    expected_state._is_done = True
+    expected = expected_state.to_json()
+
+    # Since we're essentially testing the `to_json` functionality,
+    # we explicitely ensure that the output is set
+    expected["output"] = False
+
+    assert_valid_schema(result)
+    assert_orchestration_state_equals(expected, result)