changes to iotshadow.py json None handling

.gitignore

@@ -2,3 +2,4 @@ docs/.buildinfo
 docs/.doctrees/
 __pycache__/
 *.egg-info
+build/*

awsiot/iotshadow.py

@@ -1327,16 +1327,14 @@ def __init__(self, *args, **kwargs):
     def from_payload(cls, payload):
         # type: (typing.Dict[str, typing.Any]) -> ShadowState
         new = cls()
-        val = payload.get('desired')
-        if val is not None:
-            new.desired = val
-        val = payload.get('reported')
-        if val is not None:
-            new.reported = val
-        if new.desired == None:
-            new.desired_is_nullable = True
-        if new.reported == None:
-            new.reported_is_nullable = True
+        if 'desired' in payload:
+            new.desired = payload['desired']
+            new.desired_is_nullable = new.desired is None
+
+        if 'reported' in payload:
+            new.reported = payload['reported']
+            new.reported_is_nullable = new.reported is None
+
         return new
 
     def to_payload(self):

test/test_shadow_state.py

@@ -0,0 +1,41 @@
+from pydoc import describe
+from unittest import TestCase
+
+from awsiot.iotshadow import ShadowState
+
+
+class ShadowTest(TestCase):
+
+    def test_shadow_state_payload_filled(self):
+        test_state = ShadowState.from_payload({
+            "reported": {"Color": "Red"},
+            "desired": {"Color": "Blue"}
+        })
+        compareState = ShadowState(
+            reported={"Color": "Red"},
+            desired={"Color": "Blue"}
+        )
+        self.assertTrue(test_state.to_payload() == compareState.to_payload())
+
+    def test_shadow_state_payload_partial_filled(self):
+        test_state = ShadowState.from_payload({
+            "reported": {"Color": "Red"}
+        })
+        self.assertEqual(test_state.to_payload(), {"reported": {"Color": "Red"}})
+
+    def test_shadow_state_payload_can_send_null(self):
+        test_state = ShadowState(
+            reported={"Color": "Red"},
+            desired=None,
+            desired_is_nullable=True
+        )
+        self.assertEqual(test_state.to_payload(), {"reported": {"Color": "Red"}, "desired": None})
+
+    def test_shadow_state_payload_with_none(self):
+        test_state = ShadowState.from_payload({"reported": {"Color": "Red"}, "desired": None})
+        self.assertTrue(test_state.desired_is_nullable)
+        self.assertEqual(test_state.to_payload(), {"reported": {"Color": "Red"}, "desired": None})
+
+    def test_shadow_state_payload_without_none(self):
+        test_state = ShadowState.from_payload({"reported": {"deviceAgent": {"rebootRequired": True}}})
+        self.assertEqual(test_state.to_payload(), {"reported": {"deviceAgent": {"rebootRequired": True}}})