enable reporting of warnings

.gitlab-ci.yml

@@ -78,7 +78,7 @@ build PDF documentation:
 run tests:
   stage: test
   script:
-    - py.test --cov=kwant --cov-report term --cov-report html --flakes kwant
+    - py.test -r w --cov=kwant --cov-report term --cov-report html --flakes kwant
   artifacts:
     paths:
       - htmlcov