feat: select an RDAP server by longest prefix and by TLD

Longest prefix rather than first match: a block delegated to a new
operator appears as a more specific range inside its parent, and the
wider range would name the operator that gave it away.

A TLD that publishes no RDAP service selects nothing, which is a normal
outcome for many TLDs rather than a defect.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Wrfqr2xqQfhtXCscU7zrdz

1 files changed, 51 insertions, 0 deletions

diff --git a/tests/test_rdap.py b/tests/test_rdap.py
index 3fc2c65..14a1fd4 100644
--- a/tests/test_rdap.py
+++ b/tests/test_rdap.py
@@ -125,5 +125,56 @@ class Bootstrap(unittest.TestCase):
             rdap.bootstrap("ipv4", cache_root=self.cache, fetch=fetch)
 
 
+class ServerSelection(unittest.TestCase):
+    IPV4 = {
+        "services": [
+            [["192.0.2.0/24"], ["https://wide.example.invalid/"]],
+            [["192.0.2.128/25"], ["https://narrow.example.invalid/"]],
+            [["198.51.100.0/24"], ["https://other.example.invalid/"]],
+        ]
+    }
+    DNS = {
+        "services": [
+            [["invalid"], ["https://registry.example.invalid/"]],
+            [["test"], ["https://test.example.invalid/"]],
+        ]
+    }
+
+    def test_an_address_selects_its_range(self):
+        self.assertEqual(
+            rdap.server_for_ip("198.51.100.7", self.IPV4),
+            "https://other.example.invalid/",
+        )
+
+    def test_the_longest_prefix_wins(self):
+        """192.0.2.200 is in both /24 and /25; the /25 is more specific.
+
+        Choosing the wider range would ask a registry that has delegated
+        the block away, and its answer would name the wrong operator.
+        """
+        self.assertEqual(
+            rdap.server_for_ip("192.0.2.200", self.IPV4),
+            "https://narrow.example.invalid/",
+        )
+
+    def test_an_unlisted_address_selects_nothing(self):
+        self.assertIsNone(rdap.server_for_ip("203.0.113.9", self.IPV4))
+
+    def test_a_tld_selects_its_registry(self):
+        self.assertEqual(
+            rdap.server_for_tld("invalid", self.DNS),
+            "https://registry.example.invalid/",
+        )
+
+    def test_tld_matching_ignores_case(self):
+        self.assertEqual(
+            rdap.server_for_tld("INVALID", self.DNS),
+            "https://registry.example.invalid/",
+        )
+
+    def test_an_unlisted_tld_selects_nothing(self):
+        self.assertIsNone(rdap.server_for_tld("example", self.DNS))
+
+
 if __name__ == "__main__":
     unittest.main()