add test for verbose name filter

core/tests/test_templatetags.py

@@ -0,0 +1,9 @@
+import pytest
+
+from core.models import DayOfMonth
+from core.templatetags import core_extras
+
+
+def test_verbose_name():
+    instance = DayOfMonth()
+    assert "day of month" == core_extras.verbose_name(instance)