In addition to running tests with different Python and SQLAlchemy
versions, they should also be run on different DB backends, which
are used in production (PostgreSQL and MySQL).
This patch:
- modifies test_db.cfg to run tests on PostgreSQL and MySQL
(Jenkins Slave credentials are used here, to ensure these
tests are always run by Jenkins gate); if a backend is not
available, test cases will be skipped for it
- concurrency is set to 1 (sharing of the one MySQL or PostgreSQL
DB among different test runner processes would lead to
race conditions)
- fixes tests dropping FK columns in MySQL: in earlier MySQL
versions dropping a column that is a part of a FK constraint
would lead to dropping of the FK too. As of MySQL 5.5 that's
not the case anymore: if one tries to drop such column, he/she
will get a very obscure error (something like "Error on rename
of './openstack_citest/#sql-4af_aa2' to './openstack_citest/tmp_adddropcol'
(errno: 150)") '\nALTER TABLE tmp_adddropcol DROP COLUMN r2').
So the solution if to drop FK constraints first, and only then
the columns it is made up of
Change-Id: I8c5d2874c83e7df46da69969ed54d85437c849e7
