- Improved usage of fixtures
- Replaced fixtures for directly callable factories where
multiple mock objects were needed in the same test function
- Extracted fixtures where possible (in place of literals or
global constants)
- Moved some fixtures to ``conftest.py`` to be used by other
modules
- Made a common base class for both ``TestCommandHandler`` and
``TestPrefixHandler``, extracting common methods, patterns and
signatures
- The extracted patterns in test methods have been named with
leading ``_test``
- Extracted other repeatedly used test utilities into functions
(e.g. ``is_match``) and methods (e.g. ``make_default_handler``)
