Ensure sparse backend selection sorts on driver also

Because we have --dbdriver now, we usually have
lots of db drivers queued up which affect the selection
of backend tests.   the sort in possible_configs_for_cls()
is used so that when we are only picking some backends
due to the sparse flag, we get the same answer each time
otherwise pytest-xdist raises an error if two workers
have different tests.

adding the sort for driver fixes an issue on jenkins
master build where the memusage test run frequently failed
due to mismatched test collection.

Change-Id: I8584c1a3a4e5b759c0e5a2602a93432d9cc8168d

diff --git a/lib/sqlalchemy/testing/plugin/plugin_base.py b/lib/sqlalchemy/testing/plugin/plugin_base.py
index 858814f914fd1c84cf2744d0cdfe8c309ff32282..6370d7ce95c5f9d3171210c55960868105ee9eb7 100644 (file)
--- a/lib/sqlalchemy/testing/plugin/plugin_base.py
+++ b/lib/sqlalchemy/testing/plugin/plugin_base.py
@@ -688,6 +688,7 @@ def _possible_configs_for_cls(cls, reasons=None, sparse=False):
                 all_configs,
                 key=lambda cfg: (
                     cfg.db.name,
+                    cfg.db.driver,
                     cfg.db.dialect.server_version_info,
                 ),
             )