Fix failing test_wsgi_compliance on Python 3

The list of warnings had one ResourceWarning about an unclosed socket
object.

Fixes #11.

src/zope/server/http/tests/test_wsgiserver.py

@@ -15,7 +15,7 @@
 import sys
 import unittest
 import warnings
-from contextlib import contextmanager
+from contextlib import contextmanager, closing
 from io import BytesIO, StringIO
 
 import paste.lint
@@ -197,22 +197,22 @@ def application(environ, start_response):
 
     def invokeRequest(self, path='/',
                       return_response=False):
-        h = HTTPConnection(self.LOCALHOST, self.port)
-        h.putrequest('GET', path)
-        h.putheader('Accept', 'text/plain')
-        h.endheaders()
-        response = h.getresponse()
-        if return_response:
-            return response
-        length = int(response.getheader('Content-Length', '0'))
-        if length:
-            response_body = response.read(length)
-        else:
-            response_body = b''
+        with closing(HTTPConnection(self.LOCALHOST, self.port)) as h:
+            h.putrequest('GET', path)
+            h.putheader('Accept', 'text/plain')
+            h.endheaders()
+            response = h.getresponse()
+            if return_response:
+                return response
+            length = int(response.getheader('Content-Length', '0'))
+            if length:
+                response_body = response.read(length)
+            else:
+                response_body = b''
 
-        self.assertEqual(length, len(response_body))
+            self.assertEqual(length, len(response_body))
 
-        return response.status, response_body
+            return response.status, response_body
 
 
     def testDeeperPath(self):
@@ -461,7 +461,7 @@ def test_wsgi_compliance(self):
 
         with warnings.catch_warnings(record=True) as w:
             self.invokeRequest("/foo")
-        self.assertTrue(len(w) == 0, w)
+        self.assertEqual(len(w), 0, [str(m) for m in w])
         self.server.application = orig_app
 
 class TestWSGIHttpServer(unittest.TestCase):

tox.ini

@@ -8,16 +8,14 @@ envlist =
     coverage
 
 [testenv]
-deps =
-    .[test]
+extras = test
 commands =
     zope-testrunner --test-path=src {posargs:-pvc}
 
 [testenv:coverage]
 usedevelop = true
 basepython = python3.6
 deps =
-    {[testenv]deps}
     coverage
 commands =
     coverage run -m zope.testrunner --test-path=src {posargs:-pvc}