testing pre-releases of oslo libs with apps

For integration tests, devstack installs Oslo libraries from source. We don't have a similar way to run an application's unit tests with the source version of the various libraries. Partly as a result we had 2 cases where new releases of Oslo libraries broke unit tests in applications.

As part of releasing oslotest we have set up a few jobs to allow the oslotest to be gated on the unit tests of other projects, in an attempt to avoid making changes in the test library that break running tests.

I would like to discuss the pros and cons of applying the oslotest technique to the other Oslo libraries.