Simplify and robustify the tests

test/test_required_base_class.py

@@ -11,54 +11,41 @@ class RequiredBaseClassTestCase(CheckerTestCase):
 
     CHECKER_CLASS = RequiredBaseClassChecker
 
-    def get_class_node(self, code):
-        """Parse `code`, and return the last class node.
-
-        The code should have at least one class definition.
-
-        """
-        node = astroid.parse(code)
-        class_node = None
-        for body_node in node.body:
-            if getattr(body_node, 'type', 'none') == "class":
-                class_node = body_node
-        return class_node
-
     def test_no_messages_by_default(self):
-        node = self.get_class_node('''
+        node = astroid.parse('''
             class MyClass(object):
                 pass
         ''')
         with self.assertNoMessages():
-            self.checker.visit_class(node)
+            self.walk(node)
 
     @set_config(required_base_class=["BaseClass:MyMixin"])
     def test_no_messages_if_class_not_used(self):
-        node = self.get_class_node('''
+        node = astroid.parse('''
             class MyClass(object):
                 pass
         ''')
         with self.assertNoMessages():
-            self.checker.visit_class(node)
+            self.walk(node)
 
     @set_config(required_base_class=["unittest.case.TestCase:.MyTestMixin"])
     def test_error_if_class_is_not_used(self):
-        node = self.get_class_node('''
+        node = astroid.parse('''
             from unittest import TestCase
             class MyClass(TestCase):
                 pass
         ''')
         expected_msg = Message(
             'missing-required-base-class',
-            node=node,
+            node=node.body[-1],
             args=('MyClass', '.MyTestMixin'),
         )
         with self.assertAddsMessages(expected_msg):
-            self.checker.visit_class(node)
+            self.walk(node)
 
     @set_config(required_base_class=["unittest.case.TestCase:.MyTestMixin"])
     def test_no_messages_if_class_is_used(self):
-        node = self.get_class_node('''
+        node = astroid.parse('''
             from unittest import TestCase
             class MyTestMixin(object):
                 pass
@@ -66,15 +53,15 @@ class RequiredBaseClassTestCase(CheckerTestCase):
                 pass
         ''')
         with self.assertNoMessages():
-            self.checker.visit_class(node)
+            self.walk(node)
 
     @set_config(required_base_class=["unittest.case.TestCase:.MyTestMixin"])
     def test_old_style_classes(self):
         # We don't support base class checking on old-style classes, but we
         # have to be sure not to fall over at least.
-        node = self.get_class_node('''
+        node = astroid.parse('''
             class MyClass:
                 pass
         ''')
         with self.assertNoMessages():
-            self.checker.visit_class(node)
+            self.walk(node)