Establish the session in class methods.

These are only called once, not before and after every test.

test/test_database.py

@@ -8,14 +8,16 @@ from setup import db_uri
 
 
 class DatabaseConnection(unittest.TestCase):
-    def setUp(self):
-        self.engine = create_engine(db_uri, echo=True)
-        Session = sessionmaker(bind=self.engine)
-        self.session = Session()
+    @classmethod
+    def setUpClass(cls) -> None:
+        cls.engine = create_engine(db_uri, echo=True)
+        Session = sessionmaker(bind=cls.engine)
+        cls.session = Session()
 
-    def tearDown(self):
-        self.engine.dispose()
-        self.session.close()
+    @classmethod
+    def tearDownClass(cls) -> None:
+        cls.engine.dispose()
+        cls.session.close()
 
     def test_connection(self):
         with self.engine.connect() as connection: