software/erp5/test: fix ResourceWarning on python3

 - use the requests.Session in a context manager so that resources are
properly closed.
 - close the stdout of caucase process we want to keep silent

See merge request nexedi/slapos!1075

software/erp5/test/test/test_balancer.py

@@ -110,6 +110,7 @@ class CaucaseService(ManagedResource):
             '--netloc', backend_caucased_netloc,
             '--service-auto-approve-count', '1',
         ],
+        # capture subprocess output not to pollute test's own stdout
         stdout=subprocess.PIPE,
         stderr=subprocess.STDOUT,
     )
@@ -127,6 +128,7 @@ class CaucaseService(ManagedResource):
     # type: () -> None
     self._caucased_process.terminate()
     self._caucased_process.wait()
+    self._caucased_process.stdout.close()
     shutil.rmtree(self.directory)
 
 
@@ -525,26 +527,27 @@ class TestHTTP(BalancerTestCase):
   def test_keep_alive(self):
     # type: () -> None
     # when doing two requests, connection is established only once
-    session = requests.Session()
-    session.verify = False
+    with requests.Session() as session:
+      session.verify = False
 
-    # do a first request, which establish a first connection
-    session.get(self.default_balancer_url).raise_for_status()
-
-    # "break" new connection method and check we can make another request
-    with mock.patch(
-        "requests.packages.urllib3.connectionpool.HTTPSConnectionPool._new_conn",
-    ) as new_conn:
+      # do a first request, which establish a first connection
       session.get(self.default_balancer_url).raise_for_status()
-    new_conn.assert_not_called()
-
-    parsed_url = six.moves.urllib.parse.urlparse(self.default_balancer_url)
-    # check that we have an open file for the ip connection
-    self.assertTrue([
-        c for c in psutil.Process(os.getpid()).connections()
-        if c.status == 'ESTABLISHED' and c.raddr.ip == parsed_url.hostname
-        and c.raddr.port == parsed_url.port
-    ])
+
+      # "break" new connection method and check we can make another request
+      with mock.patch(
+          "requests.packages.urllib3.connectionpool.HTTPSConnectionPool._new_conn",
+      ) as new_conn:
+        session.get(self.default_balancer_url).raise_for_status()
+      new_conn.assert_not_called()
+
+      parsed_url = six.moves.urllib.parse.urlparse(self.default_balancer_url)
+
+      # check that we have an open file for the ip connection
+      self.assertTrue([
+          c for c in psutil.Process(os.getpid()).connections()
+          if c.status == 'ESTABLISHED' and c.raddr.ip == parsed_url.hostname
+          and c.raddr.port == parsed_url.port
+      ])
 
 
 class ContentTypeHTTPServer(ManagedHTTPServer):

software/erp5/test/test/test_erp5.py

@@ -64,28 +64,28 @@ class TestPublishedURLIsReachableMixin(object):
     # erp5 site is not created, with 500 when mysql is not yet reachable, so we
     # configure this requests session to retry.
     # XXX we should probably add a promise instead
-    session = requests.Session()
-    session.mount(
-        base_url,
-        requests.adapters.HTTPAdapter(
-            max_retries=requests.packages.urllib3.util.retry.Retry(
-                total=60,
-                backoff_factor=.5,
-                status_forcelist=(404, 500, 503))))
-
-    r = session.get(virtual_host_url, verify=verify, allow_redirects=False)
-    self.assertEqual(r.status_code, requests.codes.found)
-    # access on / are redirected to login form, with virtual host preserved
-    self.assertEqual(r.headers.get('location'), 'https://virtual-host-name:1234/virtual_host_root/login_form')
-
-    # login page can be rendered and contain the text "ERP5"
-    r = session.get(
-        six.moves.urllib.parse.urljoin(base_url, '{}/login_form'.format(site_id)),
-        verify=verify,
-        allow_redirects=False,
-    )
-    self.assertEqual(r.status_code, requests.codes.ok)
-    self.assertIn("ERP5", r.text)
+    with requests.Session() as session:
+      session.mount(
+          base_url,
+          requests.adapters.HTTPAdapter(
+              max_retries=requests.packages.urllib3.util.retry.Retry(
+                  total=60,
+                  backoff_factor=.5,
+                  status_forcelist=(404, 500, 503))))
+
+      r = session.get(virtual_host_url, verify=verify, allow_redirects=False)
+      self.assertEqual(r.status_code, requests.codes.found)
+      # access on / are redirected to login form, with virtual host preserved
+      self.assertEqual(r.headers.get('location'), 'https://virtual-host-name:1234/virtual_host_root/login_form')
+
+      # login page can be rendered and contain the text "ERP5"
+      r = session.get(
+          six.moves.urllib.parse.urljoin(base_url, '{}/login_form'.format(site_id)),
+          verify=verify,
+          allow_redirects=False,
+      )
+      self.assertEqual(r.status_code, requests.codes.ok)
+      self.assertIn("ERP5", r.text)
 
   def test_published_family_default_v6_is_reachable(self):
     """Tests the IPv6 URL published by the root partition is reachable.