add aurweb.testing, a module with testing utilities

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

aurweb/testing.py

+from aurweb.db import get_engine
+
+
+def setup_test_db(*args):
+    """ This function is to be used to setup a test database before
+    using it. It takes a variable number of table strings, and for
+    each table in that set of table strings, it deletes all records.
+
+    The primary goal of this method is to configure empty tables
+    that tests can use from scratch. This means that tests using
+    this function should make sure they do not depend on external
+    records and keep their logic self-contained.
+
+    Generally used inside of pytest fixtures, this function
+    can be used anywhere, but keep in mind its functionality when
+    doing so.
+
+    Examples:
+        setup_test_db("Users", "Sessions")
+
+        test_tables = ["Users", "Sessions"];
+        setup_test_db(*test_tables)
+    """
+    engine = get_engine()
+    conn = engine.connect()
+
+    tables = list(args)
+    for table in tables:
+        conn.execute(f"DELETE FROM {table}")
+    conn.close()