DRIVERS-3162 Add test for SRV hostname validation

- Fix test name to reflect three parts

Author: aclark4life

test/asynchronous/test_dns.py

@@ -292,7 +292,7 @@ async def test_4_throw_when_return_address_does_not_contain_dot_separating_share
         ]
         await self.run_initial_dns_seedlist_discovery_prose_tests(test_cases)
 
-    async def test_5_when_srv_hostname_has_two_dot_separated_parts_it_is_valid_for_the_returned_hostname_to_be_identical(
+    async def test_5_when_srv_hostname_has_three_or_more_dot_separated_parts_it_is_valid_for_the_returned_hostname_to_be_identical(
         self
     ):
         test_cases = [

test/srv_seedlist/replica-set/identical-hostnames-valid-three-parts.json

@@ -0,0 +1,8 @@
+{
+  "uri": "mongodb+srv://build.10gen.cc/",
+  "seeds": [
+    "build.10gen.cc:27017"
+  ],
+  "ping": false,
+  "comment": "Should not throw when SRV hostname and resolved hostname are identical and SRV hostname has three dot-separated parts."
+}

test/test_dns.py

@@ -290,7 +290,7 @@ def test_4_throw_when_return_address_does_not_contain_dot_separating_shared_part
         ]
         self.run_initial_dns_seedlist_discovery_prose_tests(test_cases)
 
-    def test_5_when_srv_hostname_has_two_dot_separated_parts_it_is_valid_for_the_returned_hostname_to_be_identical(
+    def test_5_when_srv_hostname_has_three_or_more_dot_separated_parts_it_is_valid_for_the_returned_hostname_to_be_identical(
         self
     ):
         test_cases = [