By default, if you click a link through Capybara and it takes you into an external site, the current_url will work fine, but the content on the page does not change.
RackTest is the Capybara‘s default driver and it has its limitations.
> you cannot use the RackTest driver to test a remote application, or to access remote URLs
If you really need to do that know other drivers features and try them.
h/t by Nick PalaniukTweet