Fix issue with local mode bodiless responses causing clients to hang

fixes aws#525

CHANGELOG.rst

@@ -2,6 +2,14 @@
 CHANGELOG
 =========
 
+Next Release (TBD)
+==================
+
+* Fix issue with chalice local mode causing http clients to hang on responses
+  with no body
+  (`#525 <https://github.com/aws/chalice/issues/525>`__)
+
+
 1.0.2
 =====
 

Makefile

@@ -8,7 +8,7 @@ check:
 	# No unused imports, no undefined vars,
 	flake8 --ignore=E731,W503 --exclude chalice/__init__.py,chalice/compat.py --max-complexity 10 chalice/
 	flake8 --ignore=E731,W503,F401 --max-complexity 10 chalice/compat.py
-	flake8 tests/unit/ tests/functional/ tests/integration/
+	flake8 tests/unit/ tests/functional/
 	##### DOC8 ######
 	# Correct rst formatting for documentation
 	#

chalice/local.py

@@ -574,6 +574,7 @@ def _send_http_response_with_body(self, code, headers, body):
 
     def _send_http_response_no_body(self, code, headers):
         # type: (int, HeaderType) -> None
+        headers['Content-Length'] = '0'
         self.send_response(code)
         for k, v in headers.items():
             self.send_header(k, v)

tests/integration/test_features.py

@@ -238,7 +238,7 @@ def test_path_params_mapped_in_api(smoke_test_app, apig_client):
     }
 
 
-@retry(max_attempts=10, delay=6)
+@retry(max_attempts=12, delay=6)
 def _get_resource_id(apig_client, rest_api_id):
     # This is the resource id for the '/path/{name}'
     # route.  As far as I know this is the best way to get

tests/integration/test_local.py

@@ -0,0 +1,112 @@
+import socket
+import contextlib
+from threading import Thread
+from threading import Event
+
+import pytest
+import requests
+
+from chalice import app
+from chalice.local import LocalDevServer
+from chalice.config import Config
+
+
+class ThreadedLocalServer(Thread):
+    def __init__(self, port):
+        super(ThreadedLocalServer, self).__init__()
+        self._app_object = None
+        self._config = None
+        self._port = port
+        self._server = None
+        self._server_ready = Event()
+
+    def configure(self, app_object, config):
+        self._app_object = app_object
+        self._config = config
+
+    def run(self):
+        self._server = LocalDevServer(
+            self._app_object, self._config, self._port)
+        self._server_ready.set()
+        self._server.serve_forever()
+
+    def make_call(self, method, path, port, timeout=0.5):
+        self._server_ready.wait()
+        return method('http://localhost:{port}{path}'.format(
+            path=path, port=port), timeout=timeout)
+
+    def shutdown(self):
+        if self._server is not None:
+            self._server.server.shutdown()
+
+
+@pytest.fixture
+def config():
+    return Config()
+
+
+@pytest.fixture()
+def unused_tcp_port():
+    with contextlib.closing(socket.socket()) as sock:
+        sock.bind(('127.0.0.1', 0))
+        return sock.getsockname()[1]
+
+
+@pytest.fixture()
+def local_server_factory(unused_tcp_port):
+    threaded_server = ThreadedLocalServer(unused_tcp_port)
+
+    def create_server(app_object, config):
+        threaded_server.configure(app_object, config)
+        threaded_server.start()
+        return threaded_server, unused_tcp_port
+
+    try:
+        yield create_server
+    finally:
+        threaded_server.shutdown()
+
+
+@pytest.fixture
+def sample_app():
+    demo = app.Chalice('demo-app')
+
+    @demo.route('/', methods=['GET'])
+    def index():
+        return {'hello': 'world'}
+
+    @demo.route('/test-cors', methods=['POST'], cors=True)
+    def test_cors():
+        return {'hello': 'world'}
+
+    return demo
+
+
+def test_can_accept_get_request(config, sample_app, local_server_factory):
+    local_server, port = local_server_factory(sample_app, config)
+    response = local_server.make_call(requests.get, '/', port)
+    assert response.status_code == 200
+    assert response.text == '{"hello": "world"}'
+
+
+def test_can_accept_options_request(config, sample_app, local_server_factory):
+    local_server, port = local_server_factory(sample_app, config)
+    response = local_server.make_call(requests.options, '/test-cors', port)
+    assert response.headers['Content-Length'] == '0'
+    assert response.headers['Access-Control-Allow-Methods'] == 'POST,OPTIONS'
+    assert response.text == ''
+
+
+def test_can_accept_multiple_options_request(config, sample_app,
+                                             local_server_factory):
+    local_server, port = local_server_factory(sample_app, config)
+
+    response = local_server.make_call(requests.options, '/test-cors', port)
+    assert response.headers['Content-Length'] == '0'
+    assert response.headers['Access-Control-Allow-Methods'] == 'POST,OPTIONS'
+    assert response.text == ''
+
+    response = local_server.make_call(requests.options, '/test-cors', port)
+    assert response.headers['Content-Length'] == '0'
+    assert response.headers['Access-Control-Allow-Methods'] == 'POST,OPTIONS'
+    assert response.text == ''

tests/unit/test_local.py

@@ -367,6 +367,7 @@ def test_will_respond_with_custom_cors_enabled_options(handler):
     assert 'Access-Control-Expose-Headers: Header-A,Header-B' in response
     assert 'Access-Control-Max-Age: 600' in response
     assert 'Access-Control-Allow-Credentials: true' in response
+    assert 'Content-Length: 0' in response
 
     # Ensure that the Access-Control-Allow-Methods header is sent
     # and that it sends all the correct methods over.