fix(domain): match IDN TLDs against IANA list in IDNA-encoded form

src/validators/domain.py

@@ -76,7 +76,16 @@ def domain(
     if not value:
         return False
 
-    if consider_tld and not _IanaTLD.check(value.rstrip(".").rsplit(".", 1)[-1].upper()):
+    tld = value.rstrip(".").rsplit(".", 1)[-1].upper()
+    try:
+        # IANA stores internationalized TLDs in their IDNA-encoded form
+        # (e.g. "XN--P1AI"), so the lookup must use the encoded TLD too
+        tld = tld.encode("idna").decode("utf-8").upper()
+    except UnicodeError:
+        # An unencodable TLD cannot be in the IANA list; keep the raw
+        # value and let the lookup below reject it
+        pass
+    if consider_tld and not _IanaTLD.check(tld):
         return False
 
     try:

tests/test_domain.py

@@ -47,6 +47,10 @@ def test_returns_true_on_valid_domain(value: str, rfc_1034: bool, rfc_2782: bool
         ("example_.com", True, False, True),
         ("somerandomexample.xn--fiqs8s", True, False, False),
         ("somerandomexample.onion", True, False, False),
+        # internationalized TLDs are matched via their IDNA-encoded form
+        # ref: https://github.com/python-validators/validators/issues/522
+        ("пример.рф", True, False, False),
+        ("пример.рф.", True, True, False),
     ],
 )
 def test_returns_true_on_valid_top_level_domain(
@@ -100,6 +104,8 @@ def test_returns_failed_validation_on_invalid_domain(value: str, rfc_1034: bool,
         ("_example.#13", True, False, True),
         ("example_.fo-ul", True, False, True),
         ("somerandomexample.xn-n-fiqs8s", True, False, False),
+        # non-IANA IDN TLDs must still be rejected after encoding
+        ("пример.испытание", True, False, False),
     ],
 )
 def test_returns_failed_validation_invalid_top_level_domain(