Add testing case UI and functionality of the Next.js app

Consider a frontend service that has a homepage that does the following:
- [ ] it should show the headline of the website
- [ ] it should append the info from the user profile and his circle photo
- [ ] it should show the owner/user's working history
- [ ] it has a button that can be used by the visitor to join the newsletter

Test Description/criteria:
- For test 1: This test would ensure that the homepage renders the headline of the website as expected. We would use a testing library like Jest or React Testing Library to render the homepage and check that the headline is displayed correctly.
- For test 2: This test would ensure that the user's profile information and photo are appended to the headline as expected. We would use a testing library to simulate a user login and check that the user's information and photo are displayed correctly on the homepage.
- For test 3: This test would ensure that the user's working history is displayed on the homepage as expected. We would use a testing library to simulate a user login and check that the user's working history is displayed correctly on the homepage.
- For test 4: This test would ensure that the homepage has a button that can be used by the visitor to join the newsletter. We would use a testing library to render the homepage and check that the newsletter button is displayed correctly.
- For test 5: This test would ensure that when the newsletter button is clicked, a request is sent to subscribe the user to the newsletter. We would use a testing library to simulate a button click and check that the request is sent to the server correctly.