Add test for accessing uninitialized slot.

Author: fangerer

graalpython/com.oracle.graal.python.test/src/tests/test_slot.py

@@ -0,0 +1,61 @@
+# Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+# DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+#
+# The Universal Permissive License (UPL), Version 1.0
+#
+# Subject to the condition set forth below, permission is hereby granted to any
+# person obtaining a copy of this software, associated documentation and/or
+# data (collectively the "Software"), free of charge and under any and all
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+# is contributed by such licensors),
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+
+import unittest
+
+
+class A:
+    __slots__ = ("hello", "world")
+    
+    def __init__(self):
+        self.hello = "hello"
+
+
+class TestSlots(unittest.TestCase):
+    def test_uninitialized_slot(self):
+        obj = A()
+        self.assertEqual(obj.hello, "hello")
+        with self.assertRaises(AttributeError):
+            obj.world
+        obj.world = "world"
+        self.assertEqual(obj.world, "world")
+
+
+if __name__ == "__main__":
+    unittest.main()