Merge "hacking check for contextlib.nested for py34 support"

HACKING.rst

@@ -51,6 +51,7 @@ Nova Specific Commandments
   assertIn/NotIn(A, B)
 - [N339] Check common raise_feature_not_supported() is used for v2.1 HTTPNotImplemented response.
 - [N340] Check nova.utils.spawn() is used instead of greenthread.spawn() and eventlet.spawn()
+- [N341] contextlib.nested is deprecated
 
 Creating Unit Tests
 -------------------

nova/hacking/checks.py

@@ -98,6 +98,7 @@ decorator_re = re.compile(r"@.*")
 http_not_implemented_re = re.compile(r"raise .*HTTPNotImplemented\(")
 spawn_re = re.compile(
     r".*(eventlet|greenthread)\.(?P<spawn_part>spawn(_n)?)\(.*\)")
+contextlib_nested = re.compile(r"^with (contextlib\.)?nested\(")
 
 
 class BaseASTChecker(ast.NodeVisitor):
@@ -539,6 +540,16 @@ def check_greenthread_spawns(logical_line, physical_line, filename):
         yield (0, msg % {'spawn': match.group('spawn_part')})
 
 
+def check_no_contextlib_nested(logical_line, filename):
+    msg = ("N341: contextlib.nested is deprecated. With Python 2.7 and later "
+           "the with-statement supports multiple nested objects. See https://"
+           "docs.python.org/2/library/contextlib.html#contextlib.nested for "
+           "more information. nova.test.nested() is an alternative as well.")
+
+    if contextlib_nested.match(logical_line):
+        yield(0, msg)
+
+
 def factory(register):
     register(import_no_db_in_virt)
     register(no_db_session_in_public_api)
@@ -565,4 +576,5 @@ def factory(register):
     register(dict_constructor_with_list_copy)
     register(assert_equal_in)
     register(check_http_not_implemented)
+    register(check_no_contextlib_nested)
     register(check_greenthread_spawns)

nova/tests/unit/test_hacking.py

@@ -535,6 +535,31 @@ class HackingTestCase(test.NoDBTestCase):
         self._assert_has_no_errors(code, checks.check_http_not_implemented,
                                    filename=filename)
 
+    def test_check_contextlib_use(self):
+        code = """
+               with test.nested(
+                   mock.patch.object(network_model.NetworkInfo, 'hydrate'),
+                   mock.patch.object(objects.InstanceInfoCache, 'save'),
+               ) as (
+                   hydrate_mock, save_mock
+               )
+               """
+        filename = "nova/api/openstack/compute/v21/test.py"
+        self._assert_has_no_errors(code, checks.check_no_contextlib_nested,
+                                   filename=filename)
+        code = """
+               with contextlib.nested(
+                   mock.patch.object(network_model.NetworkInfo, 'hydrate'),
+                   mock.patch.object(objects.InstanceInfoCache, 'save'),
+               ) as (
+                   hydrate_mock, save_mock
+               )
+               """
+        filename = "nova/api/openstack/compute/legacy_v2/test.py"
+        errors = [(1, 0, 'N341')]
+        self._assert_has_errors(code, checks.check_no_contextlib_nested,
+                                expected_errors=errors, filename=filename)
+
     def test_check_greenthread_spawns(self):
         errors = [(1, 0, "N340")]