Apply suggestion from @encukou

Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: sethmlarson

Lib/test/test_codecs.py

@@ -1695,11 +1695,14 @@ def test_builtin_encode(self):
         self.assertEqual("pyth\xf6n.org".encode("idna"), b"xn--pythn-mua.org")
         self.assertEqual("pyth\xf6n.org.".encode("idna"), b"xn--pythn-mua.org.")
 
-    def test_new_unicode_case_folding(self):
-        self.assertEqual("ᎠᎠ".encode("idna"), b"xn--58da")
-        self.assertEqual("Ⴀ.".encode("idna"), b"xn--7md.")
-        self.assertEqual("Ӏ.example".encode("idna"), b"xn--d5a.example")
-        self.assertEqual("Ↄ.example.".encode("idna"), b"xn--q5g.example.")
+    @support.subTests(['unicode', 'encoded'], [
+        ('\N{CHEROKEE LETTER A}\N{CHEROKEE LETTER A}', b"xn--58da"),
+        ('\N{GEORGIAN CAPITAL LETTER AN}.', b"xn--7md."),
+        ('\N{CYRILLIC LETTER PALOCHKA}.example', b"xn--d5a.example"),
+        ('\N{ROMAN NUMERAL REVERSED ONE HUNDRED}.example.', b"xn--q5g.example."),
+    ])
+    def test_new_unicode_case_folding(self, unicode, encoded):
+        self.assertEqual(unicode.encode("idna"), encoded)
 
     def test_builtin_encode_invalid(self):
         for case, expected in self.invalid_encode_testcases: