If you have an instance/config.py to override local development it would also override testing.

src/spiffworkflow_backend/config/__init__.py

@@ -91,6 +91,8 @@ def setup_config(app: Flask) -> None:
     # This allows config/testing.py or instance/config.py to override the default config
     if "ENV_IDENTIFIER" in app.config and app.config["ENV_IDENTIFIER"] == "testing":
         app.config.from_pyfile("config/testing.py", silent=True)
+    elif "ENV_IDENTIFIER" in app.config and app.config["ENV_IDENTIFIER"] == "unit_testing":
+        app.config.from_pyfile("config/unit_testing.py", silent=True)
     else:
         app.config.from_pyfile(f"{app.instance_path}/config.py", silent=True)