change(aurweb): add parallel tests and improve aurweb.db

This change utilizes pytest-xdist to perform a multiproc test
run and reworks aurweb.db's code. We no longer use a global
engine, session or Session, but we now use a memo of engines
and sessions as they are requested, based on the PYTEST_CURRENT_TEST
environment variable, which is available during testing.

Additionally, this change strips several SQLite components
out of the Python code-base.

SQLite is still compatible with PHP and sharness tests, but
not with our FastAPI implementation.

More changes:
------------
- Remove use of aurweb.db.session global in other code.
- Use new aurweb.db.name() dynamic db name function in env.py.
- Added 'addopts' to pytest.ini which utilizes multiprocessing.
    - Highly recommended to leave this be or modify `-n auto` to
      `-n {cpu_threads}` where cpu_threads is at least 2.

Signed-off-by: Kevin Morris <kevr@0cost.org>

test/test_ban.py

@@ -9,18 +9,15 @@ from sqlalchemy import exc as sa_exc
 from aurweb import db
 from aurweb.db import create
 from aurweb.models.ban import Ban, is_banned
-from aurweb.testing import setup_test_db
 from aurweb.testing.requests import Request
 
 ban = request = None
 
 
 @pytest.fixture(autouse=True)
-def setup():
+def setup(db_test):
     global ban, request
 
-    setup_test_db("Bans")
-
     ts = datetime.utcnow() + timedelta(seconds=30)
     with db.begin():
         ban = create(Ban, IPAddress="127.0.0.1", BanTS=ts)
@@ -33,8 +30,6 @@ def test_ban():
 
 
 def test_invalid_ban():
-    from aurweb.db import session
-
     with pytest.raises(sa_exc.IntegrityError):
         bad_ban = Ban(BanTS=datetime.utcnow())
 
@@ -44,7 +39,7 @@ def test_invalid_ban():
         with warnings.catch_warnings():
             warnings.simplefilter("ignore", sa_exc.SAWarning)
             with db.begin():
-                session.add(bad_ban)
+                db.add(bad_ban)
 
     # Since we got a transaction failure, we need to rollback.
     db.rollback()