typing: Timestamp*Attributes in actions and conditions (#18)

Allow using Timestamp*Attributes in actions and conditions.

pynamodb_attributes/timestamp.pyi

@@ -5,15 +5,12 @@ from ._typing import Attribute
 
 
 class TimestampAttribute(Attribute[datetime]):
-    def __get__(self, instance: Any, owner: Any) -> datetime: ...
-    def __set__(self, instance: Any, value: datetime) -> None: ...
+    ...
 
 
 class TimestampMsAttribute(TimestampAttribute):
-    def __get__(self, instance: Any, owner: Any) -> datetime: ...
-    def __set__(self, instance: Any, value: datetime) -> None: ...
+    ...
 
 
 class TimestampUsAttribute(TimestampAttribute):
-    def __get__(self, instance: Any, owner: Any) -> datetime: ...
-    def __set__(self, instance: Any, value: datetime) -> None: ...
+    ...

setup.py

@@ -16,7 +16,7 @@ def find_stubs(package):  # type: ignore
 
 setup(
     name='pynamodb-attributes',
-    version='0.2.7',
+    version='0.2.8',
     description='Common attributes for PynamoDB',
     url='https://www.github.com/lyft/pynamodb-attributes',
     maintainer='Lyft',

tests/mypy_test.py

@@ -73,6 +73,7 @@ class MyModel(Model):
 
 def test_timestamp_attribute():
     assert_mypy_output("""
+    from datetime import datetime
     from pynamodb.models import Model
     from pynamodb_attributes import TimestampAttribute, TimestampMsAttribute, TimestampUsAttribute
 
@@ -82,13 +83,15 @@ class MyModel(Model):
         ts_us = TimestampUsAttribute()
 
     m = MyModel()
-    reveal_type(m.ts)  # E: Revealed type is 'datetime.datetime'
-    reveal_type(m.ts_ms)  # E: Revealed type is 'datetime.datetime'
-    reveal_type(m.ts_us)  # E: Revealed type is 'datetime.datetime'
-    m.ts = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "datetime")
-    m.ts_ms = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "datetime")
-    m.ts_us = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "datetime")
-    """)
+    reveal_type(m.ts)  # E: Revealed type is 'datetime.datetime*'
+    reveal_type(m.ts_ms)  # E: Revealed type is 'datetime.datetime*'
+    reveal_type(m.ts_us)  # E: Revealed type is 'datetime.datetime*'
+    m.ts = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "Optional[datetime]")
+    m.ts_ms = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "Optional[datetime]")
+    m.ts_us = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "Optional[datetime]")
+
+    m.save(condition=MyModel.ts == datetime.now())
+    """)  # noqa: E501
 
 
 def test_uuid_attribute():