[QGIS-Developer] Oracle tests in CI

[Julien Cabieces]

Hi all,

I propose a PR [0] to fix Oracle provider and its tests, and I would
like to enable running these tests in travis CI like it's done for
PostGis.

I succeed to build a Oracle 18c Express edition Docker image using Oracle
specific instructions [1]. I would like to push this image in a Docker
Hub (QGIS one?, an another one?) so it could be use from CI.

According to this license agreement [2], it looks like this is legally OK:
"We grant you a nonexclusive, nontransferable limited license to use the
programs for: (a) purposes of developing, prototyping and running your
applications for your own internal data processing operations;"

Do I have a good understanding of the license agreement? Do you see any
reason to not enable Oracle tests in our CI?

To be complete, it would be probably necessary to copy QGIS Oracle
database files somewhere (like it's done for ccache) to be used at run
time in order to skip Oracle database initialisation. It's quite long (around 5
minutes) and would slow down the CI.

[0] https://github.com/qgis/QGIS/pull/32337
[1] https://github.com/oracle/docker-images/tree/master/OracleDatabase/SingleInstance/dockerfiles/18.4.0
[2] https://www.oracle.com/downloads/licenses/db18c-express-license.html

Regards,
Julien