Have you looked into e2e tests? They verify that the system works as expected - so they should catch those areas that you are not testing for in your unit and integrations tests.
Check out TestCafe. You can see an example of TestCafe in action with a React + Python/Flask app -> https://testdriven.io/part-four-e2e-test-setup/
Have you looked into e2e tests? They verify that the system works as expected - so they should catch those areas that you are not testing for in your unit and integrations tests.
Check out TestCafe. You can see an example of TestCafe in action with a React + Python/Flask app -> https://testdriven.io/part-four-e2e-test-setup/