Default raw_body to empty bytestring

Changed based on the PR feedback.

chalice/app.py

@@ -265,7 +265,7 @@ def __init__(self, query_params, headers, uri_params, method, body,
         #: only be set if the Content-Type header is application/json,
         #: which is the default content type value in chalice.
         self._json_body = None
-        self._raw_body = None
+        self._raw_body = b''
         self.context = context
         self.stage_vars = stage_vars
 
@@ -277,7 +277,7 @@ def _base64decode(self, encoded):
 
     @property
     def raw_body(self):
-        if self._raw_body is None and self._body is not None:
+        if not self._raw_body and self._body is not None:
             if self._is_base64_encoded:
                 self._raw_body = self._base64decode(self._body)
             elif not isinstance(self._body, bytes):

tests/integration/test_features.py

@@ -376,7 +376,7 @@ def test_empty_raw_body(smoke_test_app):
     url = smoke_test_app.url + '/repr-raw-body'
     response = requests.post(url)
     response.raise_for_status()
-    assert response.json() == {'repr-raw-body': 'None'}
+    assert response.json() == {'repr-raw-body': ''}
 
 
 @pytest.mark.on_redeploy

tests/integration/testapp/app.py

@@ -184,4 +184,4 @@ def fake_profile_post():
 
 @app.route('/repr-raw-body', methods=['POST'])
 def repr_raw_body():
-    return {'repr-raw-body': repr(app.current_request.raw_body)}
+    return {'repr-raw-body': app.current_request.raw_body.decode('utf-8')}

tests/unit/test_app.py

@@ -1291,4 +1291,4 @@ def test_raw_body_is_none_if_body_is_none():
         'is_base64_encoded': False,
     }
     request = app.Request(body=None, **misc_kwargs)
-    assert request.raw_body is None
+    assert request.raw_body == b''