Show deprecation warnings for compat properties

Fix #3616

changelog/3616.deprecation.rst

@@ -0,0 +1,8 @@
+The following accesses have been documented as deprecated for years, but are now actually emitting deprecation warnings.
+
+* Access of ``Module``, ``Function``, ``Class``, ``Instance``, ``File`` and ``Item`` through ``Node`` instances. Now
+  users will this warning::
+
+        usage of Function.Module is deprecated, please use pytest.Module instead
+
+  Users should just ``import pytest`` and access those objects using the ``pytest`` module.

doc/en/historical-notes.rst

@@ -175,3 +175,13 @@ Previous to version 2.4 to set a break point in code one needed to use ``pytest.
 This is no longer needed and one can use the native ``import pdb;pdb.set_trace()`` call directly.
 
 For more details see :ref:`breakpoints`.
+
+"compat" properties
+-------------------
+
+.. deprecated:: 3.9
+
+Access of ``Module``, ``Function``, ``Class``, ``Instance``, ``File`` and ``Item`` through ``Node`` instances have long
+been documented as deprecated, but started to emit warnings from pytest ``3.9`` and onward.
+
+Users should just ``import pytest`` and access those objects using the ``pytest`` module.

src/_pytest/nodes.py

@@ -11,6 +11,7 @@ import _pytest._code
 from _pytest.compat import getfslineno
 
 from _pytest.mark.structures import NodeKeywords, MarkInfo
+from _pytest.warning_types import RemovedInPytest4Warning
 
 SEP = "/"
 
@@ -61,11 +62,13 @@ class _CompatProperty(object):
         if obj is None:
             return self
 
-        # TODO: reenable in the features branch
-        # warnings.warn(
-        #     "usage of {owner!r}.{name} is deprecated, please use pytest.{name} instead".format(
-        #         name=self.name, owner=type(owner).__name__),
-        #     PendingDeprecationWarning, stacklevel=2)
+        warnings.warn(
+            "usage of {owner}.{name} is deprecated, please use pytest.{name} instead".format(
+                name=self.name, owner=owner.__name__
+            ),
+            RemovedInPytest4Warning,
+            stacklevel=2,
+        )
         return getattr(__import__("pytest"), self.name)
 
 

src/_pytest/python.py

@@ -800,7 +800,7 @@ class Generator(FunctionMixin, PyCollector):
                     "%r generated tests with non-unique name %r" % (self, name)
                 )
             seen[name] = True
-            values.append(self.Function(name, self, args=args, callobj=call))
+            values.append(Function(name, self, args=args, callobj=call))
         self.warn(deprecated.YIELD_TESTS)
         return values
 

testing/deprecated_test.py

@@ -30,6 +30,23 @@ def test_yield_tests_deprecation(testdir):
     assert result.stdout.str().count("yield tests are deprecated") == 2
 
 
+def test_compat_properties_deprecation(testdir):
+    testdir.makepyfile(
+        """
+        def test_foo(request):
+            print(request.node.Module)
+    """
+    )
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(
+        [
+            "*test_compat_properties_deprecation.py:2:*usage of Function.Module is deprecated, "
+            "please use pytest.Module instead*",
+            "*1 passed, 1 warnings in*",
+        ]
+    )
+
+
 @pytest.mark.filterwarnings("default")
 def test_funcarg_prefix_deprecation(testdir):
     testdir.makepyfile(