Provision on different drivers dynamically

We want TOX_POSTGRESQL and similar to be the fixed variable
that is configured from CI environment.   These variables should refer
to database servers but individual drivers like asyncpg mysqlconnector
etc. should come from local tox.ini.  add a new system to generate
per-driver URLs from a simple list of hostname-based URLs delivered
from CI environment.

Change-Id: I4267b4a70742765388c7e7c4432c1da9d9adece2

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/provision.py b/lib/sqlalchemy/dialects/postgresql/provision.py
index 6c6dc4be6..eb82a411e 100644
--- a/lib/sqlalchemy/dialects/postgresql/provision.py
+++ b/lib/sqlalchemy/dialects/postgresql/provision.py
@@ -1,13 +1,30 @@
+import copy
 import time
 
 from ... import exc
 from ... import text
 from ...testing.provision import create_db
 from ...testing.provision import drop_db
+from ...testing.provision import generate_driver_url
 from ...testing.provision import log
 from ...testing.provision import temp_table_keyword_args
 
 
+@generate_driver_url.for_db("postgresql")
+def generate_driver_url(url, driver):
+    new_url = copy.copy(url)
+    new_url.drivername = "postgresql+%s" % driver
+    if new_url.get_driver_name() == "asyncpg":
+        new_url.query = dict(new_url.query)
+        new_url.query["async_fallback"] = "true"
+    try:
+        new_url.get_dialect()
+    except exc.NoSuchModuleError:
+        return None
+    else:
+        return new_url
+
+
 @create_db.for_db("postgresql")
 def _pg_create_db(cfg, eng, ident):
     template_db = cfg.options.postgresql_templatedb