By default, Capybara only finds visible elements, so adding the
`visible: true` option is usually redundant.
We were using it sometimes to make it an obvious contrast with another
test using `visible: false`. However, from the user's perspective, we
don't care whether the element has been removed from the DOM or has been
hidden, so we can just test that the visible selector can't be found.
Besides, using `visible: false` means the test will also pass if the
element is present and visible. However, we want the test to fail if the
element is visible. That's why a couple of JavaScript-dependant tests
were passing even when JavaScript was disabled.
We were submitting the form without checking the AJAX request to attach
the image had finished, so sometimes two requests were executed at the
same time. Sometimes this made InvisibleCaptcha to go crazy and report
the form was submitted too quickly.
Checking the first AJAX request has finished before submitting the form
solves the problem.
