As argparse now detects by default when the code was run as a module.
This leads to using the actual executable name instead of simply "python"
to display in the usage message ("usage: python -m ...").
Refactor the CLI so we can easily invoke it and mock command-line
arguments. Adapt the CLI tests so we no longer have to launch a
separate process.
Disable the busy handler for all concurrency tests; we have full
control over the order of the SQLite C API calls, so we can safely
do this.
The sqlite3 test suite now completes ~8 times faster than before.
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
