Simplifications and fixes to Task.get and Task.__setitem__ to red…

…uce surprises.

taskw/task.py

@@ -14,7 +14,7 @@
     StringField,
     UUIDField,
 )
-from taskw.fields.base import Dirtyable
+from taskw.fields.base import Dirtyable, DirtyableList, DirtyableDict
 
 # Sentinel value for not specifying a default
 UNSPECIFIED = object()
@@ -97,12 +97,10 @@ def _field_is_writable(self, key):
             return False
         return True
 
-    def get(self, key, default=UNSPECIFIED):
+    def get(self, key, default=None):
         try:
             return self[key]
         except KeyError:
-            if default is UNSPECIFIED:
-                return self._deserialize(key, None)
             return default
 
     def _record_change(self, key, from_, to):
@@ -182,18 +180,22 @@ def serialized_changes(self, keep=False):
         return serialized
 
     def __setitem__(self, key, value, force=False):
+        if isinstance(value, dict) and not isinstance(value, DirtyableDict):
+            value = DirtyableDict(value)
+        elif isinstance(value, list) and not isinstance(value, DirtyableList):
+            value = DirtyableList(value)
+
         existing_value = self.get(key)
-        if not existing_value and not value:
-            # Do not attempt to record changes if both the existing
-            # and previous values are Falsy.  We cannot distinguish
-            # between `''` and `None` for...reasons.
-            return False
         if force or value != existing_value:
-            self._record_change(
-                key,
-                self.get(key),
-                value,
-            )
+            if force or existing_value or value:
+                # Do not attempt to record changes if both the existing
+                # and previous values are Falsy.  We cannot distinguish
+                # between `''` and `None` for...reasons.
+                self._record_change(
+                    key,
+                    self.get(key),
+                    value,
+                )
 
             # Serialize just to make sure we can; it's better to throw
             # this error early.

taskw/test/test_task.py

@@ -27,11 +27,13 @@ def setUp(self):
         })
 
     def test_append_when_absent(self):
+        self.task['annotations'] = []
         self.task['annotations'].append('awesome')
         self.assertEqual(self.task['annotations'], ['awesome'])
 
     def test_append_when_absent_but_with_tags(self):
         self.task = Task({'uuid': str(uuid.uuid4()), 'description': 'Test'})
+        self.task['tags'] = []
         self.task['tags'].append('awesome')
         self.assertEqual(self.task['tags'], ['awesome'])