Fix exception catching in coroutines.

tests/integration/test_tornado.py

@@ -284,3 +284,17 @@ def test_tornado_with_decorator_use_cassette(get_client):
         http.HTTPRequest('http://www.google.com/', method='GET')
     )
     assert response.body.decode('utf-8') == "not actually google"
+
+
+@pytest.mark.gen_test
+@vcr.use_cassette(path_transformer=vcr.default_vcr.ensure_suffix('.yaml'))
+def test_tornado_exception_can_be_caught(get_client):
+    try:
+        yield get(get_client(), 'http://httpbin.org/status/500')
+    except http.HTTPError as e:
+        assert e.code == 500
+
+    try:
+        yield get(get_client(), 'http://httpbin.org/status/404')
+    except http.HTTPError as e:
+        assert e.code == 404

tests/integration/test_tornado_exception_can_be_caught.yaml

@@ -0,0 +1,62 @@
+interactions:
+- request:
+    body: null
+    headers: {}
+    method: GET
+    uri: http://httpbin.org/status/500
+  response:
+    body: {string: !!python/unicode ''}
+    headers:
+    - !!python/tuple
+      - Content-Length
+      - ['0']
+    - !!python/tuple
+      - Server
+      - [nginx]
+    - !!python/tuple
+      - Connection
+      - [close]
+    - !!python/tuple
+      - Access-Control-Allow-Credentials
+      - ['true']
+    - !!python/tuple
+      - Date
+      - ['Thu, 30 Jul 2015 17:32:39 GMT']
+    - !!python/tuple
+      - Access-Control-Allow-Origin
+      - ['*']
+    - !!python/tuple
+      - Content-Type
+      - [text/html; charset=utf-8]
+    status: {code: 500, message: INTERNAL SERVER ERROR}
+- request:
+    body: null
+    headers: {}
+    method: GET
+    uri: http://httpbin.org/status/404
+  response:
+    body: {string: !!python/unicode ''}
+    headers:
+    - !!python/tuple
+      - Content-Length
+      - ['0']
+    - !!python/tuple
+      - Server
+      - [nginx]
+    - !!python/tuple
+      - Connection
+      - [close]
+    - !!python/tuple
+      - Access-Control-Allow-Credentials
+      - ['true']
+    - !!python/tuple
+      - Date
+      - ['Thu, 30 Jul 2015 17:32:39 GMT']
+    - !!python/tuple
+      - Access-Control-Allow-Origin
+      - ['*']
+    - !!python/tuple
+      - Content-Type
+      - [text/html; charset=utf-8]
+    status: {code: 404, message: NOT FOUND}
+version: 1

vcr/cassette.py

@@ -1,3 +1,4 @@
+import sys
 import inspect
 import logging
 
@@ -87,16 +88,21 @@ class CassetteContextDecorator(object):
         return handler(function, args, kwargs)
 
     def _handle_coroutine(self, function, args, kwargs):
+        """Wraps a coroutine so that we're inside the cassette context for the
+        duration of the coroutine.
+        """
         with self as cassette:
             coroutine = self.__handle_function(cassette, function, args, kwargs)
-            to_send = None
+            # We don't need to catch StopIteration. The caller (Tornado's
+            # gen.coroutine, for example) will handle that.
+            to_yield = next(coroutine)
             while True:
                 try:
-                    to_yield = coroutine.send(to_send)
-                except StopIteration:
-                    break
-                else:
                     to_send = yield to_yield
+                except Exception:
+                    to_yield = coroutine.throw(*sys.exc_info())
+                else:
+                    to_yield = coroutine.send(to_send)
 
     def __handle_function(self, cassette, function, args, kwargs):
         if cassette.inject: