Extend validate-modules to check the next to last line (#34819)

* Add validation for the next to last line of a module

* Fix last error code

* Reduce to a single conditional

* Fix conditionals

* Move the final warnings statement to main() in mysql_replication

docs/docsite/rst/dev_guide/testing_validate-modules.rst

@@ -70,6 +70,7 @@ Errors
             ``DOCUMENTATION``/``EXAMPLES``/``RETURN``/``ANSIBLE_METADATA``
   107       Imports should be directly below ``DOCUMENTATION``/``EXAMPLES``/``RETURN``/``ANSIBLE_METADATA``
   108       GPLv3 license header should be the :ref:`short form <copyright>` for new modules
+  109       Next to last line is not ``if __name__ == "__main__":``
   ..
 ---------   -------------------
   **2xx**   **Imports**

lib/ansible/modules/database/mysql/mysql_replication.py

@@ -359,7 +359,8 @@ def main():
         else:
             module.exit_json(msg="Slave already reset", changed=False)
 
+    warnings.simplefilter("ignore")
+
 
 if __name__ == '__main__':
     main()
-    warnings.simplefilter("ignore")

test/sanity/validate-modules/main.py

@@ -518,6 +518,30 @@ class ModuleValidator(Validator):
         bodies.extend(if_bodies)
 
         for child in bodies:
+
+            # validate that the next to last line is 'if __name__ == "__main__"'
+            if child.lineno == (self.length - 1):
+
+                mainchecked = False
+                try:
+                    if isinstance(child, ast.If) and \
+                            child.test.left.id == '__name__' and \
+                            len(child.test.ops) == 1 and \
+                            isinstance(child.test.ops[0], ast.Eq) and \
+                            child.test.comparators[0].s == '__main__':
+                        mainchecked = True
+                except Exception:
+                    pass
+
+                if not mainchecked:
+                    self.reporter.error(
+                        path=self.object_path,
+                        code=109,
+                        msg='Next to last line should be: if __name__ == "__main__":',
+                        line=child.lineno
+                    )
+
+            # validate that the final line is a call to main()
             if isinstance(child, ast.Expr):
                 if isinstance(child.value, ast.Call):
                     if (isinstance(child.value.func, ast.Name) and