How to maximize browser in minitest-rails selenium test?

I'm doing minitest-rails with feature testing.

I noticed that the browser (i'm using chrome) is NOT in full width.

Where or how can I set it in my configuration file?

Currently I have installed the following gems:

  selenium-webdriver (2.53.4)
  chromedriver-helper (1.0.0)
  capybara (2.8.1, 2.7.1)
  capybara-screenshot (1.0.13)
  minitest-capybara (0.8.2)
  minitest-rails-capybara (2.1.2)

Please help!