Add functional tests

Author: Julfried

tests/pyreverse/functional/class_diagrams/attributes/duplicates_9267.mmd

@@ -0,0 +1,9 @@
+classDiagram
+  class A {
+    var : int
+  }
+  class B {
+    a_obj
+    func()
+  }
+  A --* B : a_obj

tests/pyreverse/functional/class_diagrams/attributes/duplicates_9267.py

@@ -0,0 +1,12 @@
+# Test for https://github.com/pylint-dev/pylint/issues/9267
+class A:
+    def __init__(self) -> None:
+        self.var = 2
+
+class B:
+    def __init__(self) -> None:
+        self.a_obj = A()
+
+    def func(self):
+        self.a_obj = A()
+        self.a_obj = A()