introduce deprecation warnings for legacy parametersets, fixes #2427

_pytest/deprecated.py

@@ -31,3 +31,9 @@ RESULT_LOG = '--result-log is deprecated and scheduled for removal in pytest 4.0
 MARK_INFO_ATTRIBUTE = RemovedInPytest4Warning(
     "MarkInfo objects are deprecated as they contain the merged marks"
 )
+
+MARK_PARAMETERSET_UNPACKING = RemovedInPytest4Warning(
+    "Applying marks directly to parameters is deprecated,"
+    " please use pytest.param(..., marks=...) instead.\n"
+    "For more details, see: https://docs.pytest.org/en/latest/parametrize.html"
+)

_pytest/mark.py

@@ -6,7 +6,7 @@ import warnings
 from collections import namedtuple
 from operator import attrgetter
 from .compat import imap
-from .deprecated import MARK_INFO_ATTRIBUTE
+from .deprecated import MARK_INFO_ATTRIBUTE, MARK_PARAMETERSET_UNPACKING
 
 def alias(name, warning=None):
     getter = attrgetter(name)
@@ -61,6 +61,9 @@ class ParameterSet(namedtuple('ParameterSet', 'values, marks, id')):
         if legacy_force_tuple:
             argval = argval,
 
+        if newmarks:
+            warnings.warn(MARK_PARAMETERSET_UNPACKING)
+
         return cls(argval, marks=newmarks, id=None)
 
     @property

changelog/2427.removal

@@ -0,0 +1 @@
+introduce deprecation warnings for legacy marks based parametersets