Bring up URI check for sqlite engine

Includes a test to check that a database file is not created when using
sqlite URI for in memory.

src/flask_sqlalchemy/extension.py

@@ -607,22 +607,22 @@ def _apply_driver_defaults(self, options: dict[str, t.Any], app: Flask) -> None:
         url = sa.engine.make_url(options["url"])
 
         if url.drivername in {"sqlite", "sqlite+pysqlite"}:
-            if url.database is None or url.database in {"", ":memory:"}:
+            # the url might look like sqlite:///file:path?uri=true
+            is_uri = url.query.get("uri", False)
+
+            if is_uri and url.database:
+                db_str: t.Optional[str] = url.database[5:]
+            else:
+                db_str = url.database
+
+            if db_str is None or db_str in {"", ":memory:"}:
                 options["poolclass"] = sa.pool.StaticPool
 
                 if "connect_args" not in options:
                     options["connect_args"] = {}
 
                 options["connect_args"]["check_same_thread"] = False
             else:
-                # the url might look like sqlite:///file:path?uri=true
-                is_uri = url.query.get("uri", False)
-
-                if is_uri:
-                    db_str = url.database[5:]
-                else:
-                    db_str = url.database
-
                 if not os.path.isabs(db_str):
                     os.makedirs(app.instance_path, exist_ok=True)
                     db_str = os.path.join(app.instance_path, db_str)

tests/test_engine.py

@@ -110,6 +110,16 @@ def test_sqlite_driver_level_uri(app: Flask, model_class: t.Any) -> None:
     assert os.path.exists(db_path[5:])
 
 
+@pytest.mark.usefixtures("app_ctx")
+def test_sqlite_driver_level_uri_in_memory(app: Flask, model_class: t.Any) -> None:
+    app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///file::memory:?uri=true"
+    db = SQLAlchemy(app, model_class=model_class)
+    db.create_all()
+    db_path = db.engine.url.database
+    assert db_path is not None
+    assert not os.path.exists(db_path[5:])
+
+
 @unittest.mock.patch.object(SQLAlchemy, "_make_engine", autospec=True)
 def test_sqlite_memory_defaults(
     make_engine: unittest.mock.Mock, app: Flask, model_class: t.Any