PYTHON-2295 MongoClient with multiple hosts directConnection=True should raise an error (#446)

Author: prashantmital

pymongo/mongo_client.py

@@ -670,6 +670,11 @@ def __init__(
         # Normalize combined options.
         opts = _normalize_options(opts)
 
+        # Ensure directConnection was not True if there are multiple seeds.
+        if len(seeds) > 1 and opts.get('directconnection'):
+            raise ConfigurationError(
+                "Cannot specify multiple hosts with directConnection=true")
+
         # Username and password passed as kwargs override user info in URI.
         username = opts.get("username", username)
         password = opts.get("password", password)

test/test_client.py

@@ -1572,6 +1572,10 @@ def test_direct_connection(self):
                        TOPOLOGY_TYPE.ReplicaSetWithPrimary])
         client.close()
 
+        # directConnection=True, should error with multiple hosts as a list.
+        with self.assertRaises(ConfigurationError):
+            MongoClient(['host1', 'host2'], directConnection=True)
+
 
 class TestExhaustCursor(IntegrationTest):
     """Test that clients properly handle errors from exhaust cursors."""