[3.13] pythongh-136599: Add tests for long_hash (pythonGH-138335) (python#138391)

pythongh-136599: Add tests for long_hash (pythonGH-138335)
(cherry picked from commit 2d3711d)

Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>

Author: 3 people

Lib/test/test_long.py

@@ -1642,5 +1642,21 @@ class MyInt(int):
         # GH-117195 -- This shouldn't crash
         object.__sizeof__(1)
 
+    def test_hash(self):
+        # gh-136599
+        self.assertEqual(hash(-1), -2)
+        self.assertEqual(hash(0), 0)
+        self.assertEqual(hash(10), 10)
+
+        self.assertEqual(hash(sys.hash_info.modulus - 2), sys.hash_info.modulus - 2)
+        self.assertEqual(hash(sys.hash_info.modulus - 1), sys.hash_info.modulus - 1)
+        self.assertEqual(hash(sys.hash_info.modulus), 0)
+        self.assertEqual(hash(sys.hash_info.modulus + 1), 1)
+
+        self.assertEqual(hash(-sys.hash_info.modulus - 2), -2)
+        self.assertEqual(hash(-sys.hash_info.modulus - 1), -2)
+        self.assertEqual(hash(-sys.hash_info.modulus), 0)
+        self.assertEqual(hash(-sys.hash_info.modulus + 1), -sys.hash_info.modulus + 1)
+
 if __name__ == "__main__":
     unittest.main()