chore: use dns_server only on DNS tests

Author: jackwotherspoon

tests/conftest.py

@@ -154,7 +154,7 @@ async def cache(fake_client: CloudSQLClient) -> AsyncGenerator[RefreshAheadCache
     await cache.close()
 
 
-@pytest.fixture(autouse=True, scope="session")
+@pytest.fixture()
 def dns_server() -> Generator:
     """Setup local DNS server for tests with TXT records."""
     server = DNSServer.from_toml("tests/test_zones.toml", port=5053, upstream=None)

tests/unit/test_resolver.py

@@ -37,6 +37,7 @@ async def test_DnsResolver_with_conn_str() -> None:
     assert result == conn_name
 
 
+@pytest.mark.usefixtures("dns_server")
 async def test_DnsResolver_with_dns_name() -> None:
     """Test DnsResolver resolves TXT record into proper instance connection name."""
     resolver = DnsResolver()
@@ -45,6 +46,7 @@ async def test_DnsResolver_with_dns_name() -> None:
     assert result == conn_name
 
 
+@pytest.mark.usefixtures("dns_server")
 async def test_DnsResolver_with_malformed_txt() -> None:
     """Test DnsResolver with TXT record that holds malformed instance connection name.
 
@@ -60,6 +62,7 @@ async def test_DnsResolver_with_malformed_txt() -> None:
         )
 
 
+@pytest.mark.usefixtures("dns_server")
 async def test_DnsResolver_with_bad_dns_name() -> None:
     """Test DnsResolver with bad dns name.