How to properly test web applications?

Question

Data storage

Good afternoon, I recently started learning the basics of development through TDD (BDD).
Everything is relatively clear and understandable with writing tests (and benchmarks) for NON web application code (for this I use the Goconvey library ) The
question does not apply directly to any PL or library, it is interesting to design testing for a web application (site, service) . How to check if the page is rendered correctly, check the restriction of user rights and other aspects, as well as testing the UI, but this is most likely a completely different story.
Thank you for your attention and answers :)

Answer 1

I use hubic with the "leave files on the server" option,
the box and the disk probably also have something like that, but I quickly found it when I was looking

Answer 2

Selenium
Codeception

Answer 3

Apache HTTP server benchmarking tool

Answer 4

For testing SPA applications, it is convenient to use PhantomJS / CasperJS
For forntend + backend - Selenium bundles
Specifically, in the browser you can use mochaJS
On the backend - it depends on the language