Thanks andrewbadr for the report and Carl Meyer for the review.

Each TestCase is also now wrapped in a class-wide transaction.

Without this patch, you couldn't run an individual test
case in template_tests.

Refs #23768

Refs #23843 which is really a cx_Oracle bug

Based on Daniel Wiesmann's work. Refs #23804.

GDAL raster methods return different error codes from the vector
API.

Refs #23804.

The failure was introduced in dd1ea707.
The tests wouldn't start due to a "Dependency on unknown app" error.

Refs: #15346, #15573, #16353, #16828.

Thanks James Rivett-Carnac for the report and Markus Holtermann
for the review.

It was originally added to fix a test (refs #7514); but Site now has a
pre_save signal handler (refs #19698) to clear the cache which makes
this call redundant.

StringIO import was adapted for compatibility with Python 2.

Creating a new cluster is neither required not recommendable for
most users. The previous section explains how to create a user
with sufficient permissions to automatically create a database
during tests.

Warnings could escape depending on the order in which tests were run.