Only check session timeout if the session is not empty

src/django_session_timeout/middleware.py

@@ -14,7 +14,7 @@
 
 class SessionTimeoutMiddleware(MiddlewareMixin):
     def process_request(self, request):
-        if not hasattr(request, 'session'):
+        if not hasattr(request, 'session') or request.session.is_empty():
             return
 
         init_time = request.session.setdefault(SESSION_TIMEOUT_KEY, time.time())

tests/test_middleware.py

@@ -11,6 +11,8 @@ def r(rf):
     req = rf.get('/')
     middleware = SessionMiddleware()
     middleware.process_request(req)
+    req.session['example_key'] = '1'
+
     req.session.save()
     yield req
 
@@ -21,6 +23,14 @@ def test_session_new(r):
     assert r.session[SESSION_TIMEOUT_KEY]
 
 
+def test_session_new_empty_session(r):
+    r.session.flush()
+
+    middleware = SessionTimeoutMiddleware()
+    assert middleware.process_request(r) is None
+    assert SESSION_TIMEOUT_KEY not in r.session
+
+
 def test_session_expire(r, settings):
     settings.SESSION_EXPIRE_SECONDS = 3600
     middleware = SessionTimeoutMiddleware()