Add checkers for typing.final for Python version 3.8 or later (#5133)

* Add checkers for typing.final for Python version 3.8 or later

- overridden-final-method
- subclassed-final-class

Closes #3197

3 files changed, 20 insertions, 0 deletions

diff --git a/tests/functional/o/overridden_final_method_py38.py b/tests/functional/o/overridden_final_method_py38.py
new file mode 100644
index 000000000..d951c26da
--- /dev/null
+++ b/tests/functional/o/overridden_final_method_py38.py
@@ -0,0 +1,17 @@
+"""Since Python version 3.8, a method decorated with typing.final cannot be
+overridden"""
+
+# pylint: disable=no-init, import-error, invalid-name, using-constant-test, useless-object-inheritance
+# pylint: disable=missing-docstring, too-few-public-methods
+
+from typing import final
+
+class Base:
+    @final
+    def my_method(self):
+        pass
+
+
+class Subclass(Base):
+    def my_method(self): # [overridden-final-method]
+        pass
diff --git a/tests/functional/o/overridden_final_method_py38.rc b/tests/functional/o/overridden_final_method_py38.rc
new file mode 100644
index 000000000..85fc502b3
--- /dev/null
+++ b/tests/functional/o/overridden_final_method_py38.rc
@@ -0,0 +1,2 @@
+[testoptions]
+min_pyver=3.8
diff --git a/tests/functional/o/overridden_final_method_py38.txt b/tests/functional/o/overridden_final_method_py38.txt
new file mode 100644
index 000000000..2c8bca442
--- /dev/null
+++ b/tests/functional/o/overridden_final_method_py38.txt
@@ -0,0 +1 @@
+overridden-final-method:16:4:Subclass.my_method:Method 'my_method' overrides a method decorated with typing.final which is defined in class 'Base':HIGH