We have hundreds of tests for our client side projects (web app, mobile app), and they definitely do more than what you describe.
Some are simple (although very few are as simple as your example) and some are complex, depending on the portion of the app being tested. Some are basically integration tests for components/widgets, where it runs it in isolation to test the inputs and outputs. Others are more like traditional unit tests where it's purely testing business logic, API and model interactions (mocked), form validation logic, etc.
Unless you're talking about very simple client apps, there's always stuff that can be tested that will provide significant business value by preventing bugs and broken code from getting to end users
Some are simple (although very few are as simple as your example) and some are complex, depending on the portion of the app being tested. Some are basically integration tests for components/widgets, where it runs it in isolation to test the inputs and outputs. Others are more like traditional unit tests where it's purely testing business logic, API and model interactions (mocked), form validation logic, etc.
Unless you're talking about very simple client apps, there's always stuff that can be tested that will provide significant business value by preventing bugs and broken code from getting to end users