Merge remote-tracking branch 'upstream/features' into invocation-scoped-fixtures

_pytest/fixtures.py

@@ -878,7 +878,12 @@ def yield_fixture(scope="function", params=None, autouse=False, ids=None, name=N
     else:
         return FixtureFunctionMarker(scope, params, autouse, ids=ids, name=name)
 
+
 defaultfuncargprefixmarker = fixture()
+funcarg_prefix_warning = (
+    '{name}: declaring fixtures using "pytest_funcarg__" prefix is deprecated '
+    'and scheduled to be removed in pytest 4.0.  '
+    'Please remove the prefix and use the @pytest.fixture decorator instead.')
 
 
 @fixture(scope="session")
@@ -887,8 +892,6 @@ def pytestconfig(request):
     return request.config
 
 
-
-
 class FixtureManager:
     """
     pytest fixtures definitions and information is stored and managed
@@ -1063,6 +1066,7 @@ class FixtureManager:
                 if not callable(obj):
                     continue
                 marker = defaultfuncargprefixmarker
+                self.config.warn('C1', funcarg_prefix_warning.format(name=name))
                 name = name[len(self._argprefix):]
             elif not isinstance(marker, FixtureFunctionMarker):
                 # magic globals  with __getattr__ might have got us a wrong
@@ -1071,7 +1075,9 @@ class FixtureManager:
             else:
                 if marker.name:
                     name = marker.name
-                assert not name.startswith(self._argprefix), name
+                msg = 'fixtures cannot have "pytest_funcarg__" prefix ' \
+                      'and be decorated with @pytest.fixture:\n%s' % name
+                assert not name.startswith(self._argprefix), msg
 
             def new_fixture_def(name, scope):
                 """Create and registers a new FixtureDef with given name and scope."""