for tests.

I've seen
He use cucumber with rspec and capybara for tests.
What do you think?
I'm reading about cucumber but I don't know anything about capybara.

Capybara aims to simplify the process of integration testing Rack applications, such as Rails, Sinatra or Merb. It is agnostic about the driver running your tests and currently comes bundled with rack-test, Culerity, Celerity and Selenium support built in. env.js support is available as the capybara-envjs gem.
Capybara is built to work nicely with Cucumber. Its API is very similar to that of Webrat. It is inspired by and aims to replace Webrat as a DSL for interacting with a webapplication.

Check more here:

Do you advise me to use cucumber for test?

Cucumber is designed for Behaviour Driven Development (BDD). Some also propagate that BDD is the future of software engineering. If you are goal is BDD, then Cucumber is the answer. I use Cucumber myself.

But you should know that there are levels of testing. Cucumber is for high level testing. You also need to look at other testing tools for low level. Rspec, Unit Testing and Shoulda are good examples.

Msan Msan wrote:

Do you advise me to use cucumber for test?

Absolutely, for user-facing behavior (equivalent to functional and
integration tests). For unit and similar tests, just use RSpec.