Add get_database_version and set_database_version methods to DatabaseManager class

[Ryan J Ollos]

As an incremental step towards the changes outlined in #8172, I propose to add get_database_version and set_database_version methods to the DatabaseManager class.

I implemented these changes as part of another ticket and ended up not needing them, so it seemed worthwhile to commit the changes as a refactoring and database API enhancement.

[Ryan J Ollos]

I haven't tested the changes yet with MySQL and PostgreSQL. Docstrings need to be added as well.

log:rjollos.git:t11859

[Ryan J Ollos]

Tests pass with SQLite, MySQL and PostgreSQL. Added docstrings.

Committed to trunk in [13455]. Documented in TracDev/ApiChanges/1.1.3@14.

[Ryan J Ollos]

It seems to be a given that I'll break the build on commit, despite all the test runs passing locally. make Trac.egg-info compile unit-test functional-test passes for me. The database should be destroyed because database_version was incremented and no longer matches db_default, however the following error is seen in the automated builds:

OperationalError: table system already exists

I put a workaround in place in [13460], which is probably better anyway since the tests will run slightly faster.

[Peter Suter]

DatabaseManager(self)​ should be DatabaseManager(self.env) or you get AssertionError: First argument must be a ComponentManager instance because here self is EnvironmentSetup(Component), not Environment(ComponentManager).

[Peter Suter]

Replying to psuter:

DatabaseManager(self)​ should be DatabaseManager(self.env)

Committed in [13462].

[Ryan J Ollos]

Thanks, I'll look into adding some test coverage for that.

[Ryan J Ollos]

Minor refactoring in [13574].