gh-99688: Fix outdated tests in test_unary (#99712)

* Remove duplicates from "L" suffix removal
* test_invert now tests `~`.

Author: Isaac-Lee

Lib/test/test_unary.py

@@ -8,23 +8,20 @@ def test_negative(self):
         self.assertTrue(-2 == 0 - 2)
         self.assertEqual(-0, 0)
         self.assertEqual(--2, 2)
-        self.assertTrue(-2 == 0 - 2)
         self.assertTrue(-2.0 == 0 - 2.0)
         self.assertTrue(-2j == 0 - 2j)
 
     def test_positive(self):
         self.assertEqual(+2, 2)
         self.assertEqual(+0, 0)
         self.assertEqual(++2, 2)
-        self.assertEqual(+2, 2)
         self.assertEqual(+2.0, 2.0)
         self.assertEqual(+2j, 2j)
 
     def test_invert(self):
-        self.assertTrue(-2 == 0 - 2)
-        self.assertEqual(-0, 0)
-        self.assertEqual(--2, 2)
-        self.assertTrue(-2 == 0 - 2)
+        self.assertTrue(~2 == -(2+1))
+        self.assertEqual(~0, -1)
+        self.assertEqual(~~2, 2)
 
     def test_no_overflow(self):
         nines = "9" * 32