pytest: use --strict (#5966)

blueyed · tomchristie · commit fd4282c7fa3e · 2018-05-03T21:43:57.000+01:00
This causes errors with invalid markers: > AttributeError: 'skipUnless' not a registered marker Fixed in #5965.
diff --git a/tox.ini b/tox.ini
@@ -1,5 +1,5 @@
 [pytest]
-addopts=--tb=short
+addopts=--tb=short --strict
 
 [tox]
 envlist =
