Testing: Update Existing Unit Test Cases and Implement New Front-end Tests Using Streamlit Test Drivers

[georgetayqy]

As the application grows in complexity and depth, we need to increase the number of test cases and integrate new types of tests to ensure that the application performs as expected.

Let's move to update existing unit test cases, and implement front-end tests enabled by the testing functionality embedded into Streamlit. We could also consider implementing integration, system, and user acceptance tests.