Allow multiple versions of single backendallow_multi_backends

Improve screen output to illustrate which server version is
running for a particular database config, and additionally
allow full overriding for the backend-specific targets in
tox.ini via environment variables, so that CI can inject
multiple server urls for a particular database such as MySQL/MariaDB.

Change-Id: Ibf443bb9fb82e4563efd1bb66058fa9989aa2fda

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/sqlalchemy/testing/plugin/plugin_base.py b/lib/sqlalchemy/testing/plugin/plugin_base.py
index 996cf4582..e01fa9bd0 100644
--- a/lib/sqlalchemy/testing/plugin/plugin_base.py
+++ b/lib/sqlalchemy/testing/plugin/plugin_base.py
@@ -409,12 +409,12 @@ def want_method(cls, fn):
 def generate_sub_tests(cls, module):
     if getattr(cls, '__backend__', False):
         for cfg in _possible_configs_for_cls(cls):
-            name = "%s_%s_%s" % (cls.__name__, cfg.db.name, cfg.db.driver)
+            name = "%s_%s" % (cls.__name__, cfg.name)
             subcls = type(
                 name,
                 (cls, ),
                 {
-                    "__only_on__": ("%s+%s" % (cfg.db.name, cfg.db.driver)),
+                    "__only_on_config__": cfg
                 }
             )
             setattr(module, name, subcls)
@@ -489,6 +489,9 @@ def _possible_configs_for_cls(cls, reasons=None):
             if not spec(config_obj):
                 all_configs.remove(config_obj)
 
+    if getattr(cls, '__only_on_config__', None):
+        all_configs.intersection_update([cls.__only_on_config__])
+
     if hasattr(cls, '__requires__'):
         requirements = config.requirements
         for config_obj in list(all_configs):