Just built this little snippet in a hacknight, it simulates a geolcation via capybara, so you can test if you geo-magic actually works 🙂

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<p>Finding your location... <span id="status">checking...</span></p>
<script>
  jQuery(function () {
    var timeout = (document.location.href.indexOf('test_location') >= 0 ? 100 : 0);

    setTimeout(function(){
      navigator.geolocation.getCurrentPosition(function(){
        jQuery('#status').html("found you!");
      });
    }, timeout)
  });
</script>

Capybara test via selenium in rspec

  def simulate_location(lat, lng)
    page.driver.browser.execute_script <<-JS
      window.navigator.geolocation.getCurrentPosition = function(success){
        var position = {"coords" : { "latitude": "#{lat}", "longitude": "#{lng}" }};
        success(position);
      }
    JS
  end

  it "can use location", :js => true do
    visit '/?test_location=true'
    simulate_location 20, 20
    sleep 0.2
    page.should have_content "found you!"
  end