Custom matcher example

custom_matcher.rb

# On spec/rails_helper.rb
...
config.include Matchers, type: :feature
...

# Separate spec/support/matchers/matchers.rb into two files:
# spec/support/matchers/tabs.rb
module Matchers
  matcher :have_active_tab do |tab_name|
    match do |page|
      expect(page).to have_css(
        'li[aria-controls="#{tab_name}"][aria-selected=true].ui-state-active'
      )
    end
  end

  matcher :have_inactive_tab do |tab_name|
    match do |page|
      expect(page).to have_css(
        'li[aria-controls="#{tab_name}"][aria-selected=false]'
      )
    end
  end
end

# and spec/support/matchers/uri.rb
module Matchers
  matcher :have_query_string do |tab_name, options|
    match do |url|
      uri = URI.parse(url)
      expect(uri.query).to include "#{tab_name}=#{options[:with]}"
    end
  end
end

# And the spec/support/matchers.rb
module Matchers
  extend RSpec::Matchers::DSL
  include Capybara::DSL
end