diff --git a/.gitignore b/.gitignore
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@
 *.egg-info
 version.txt
 swh/lister/_version.py
+.tox/
diff --git a/swh/lister/core/db_utils.py b/swh/lister/core/db_utils.py
--- a/swh/lister/core/db_utils.py
+++ b/swh/lister/core/db_utils.py
@@ -11,7 +11,7 @@
     try:
         yield session
         session.commit()
-    except:
+    except:  # noqa
         session.rollback()
         raise
     finally:
diff --git a/swh/lister/core/lister_base.py b/swh/lister/core/lister_base.py
--- a/swh/lister/core/lister_base.py
+++ b/swh/lister/core/lister_base.py
@@ -292,8 +292,9 @@
                 r = self.transport_request(identifier)
             except FetchError:
                 # network-level connection error, try again
-                logging.warn('connection error on %s: sleep for %d seconds' %
-                             (identifier, self.CONN_SLEEP))
+                logging.warning(
+                    'connection error on %s: sleep for %d seconds' %
+                    (identifier, self.CONN_SLEEP))
                 time.sleep(self.CONN_SLEEP)
                 retries_left -= 1
                 continue
@@ -304,8 +305,9 @@
             # detect throttling
             must_retry, delay = self.transport_quota_check(r)
             if must_retry:
-                logging.warn('rate limited on %s: sleep for %f seconds' %
-                             (identifier, delay))
+                logging.warning(
+                    'rate limited on %s: sleep for %f seconds' %
+                    (identifier, delay))
                 time.sleep(delay)
             else:  # request ok
                 break
@@ -313,7 +315,8 @@
             retries_left -= 1
 
         if not retries_left:
-            logging.warn('giving up on %s: max retries exceeded' % identifier)
+            logging.warning(
+                'giving up on %s: max retries exceeded' % identifier)
 
         return r
 
diff --git a/tox.ini b/tox.ini
new file mode 100644
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,16 @@
+[tox]
+envlist=flake8,py3
+
+[testenv:py3]
+deps =
+  .[testing]
+  pytest-cov
+commands =
+  pytest --cov=swh --cov-branch {posargs}
+
+[testenv:flake8]
+skip_install = true
+deps =
+  flake8
+commands =
+  {envpython} -m flake8