Using `have_current_path`, Capybara waits until the condition is true,
while using `include` the expectation is evaluated immediately and so
tests might fail when using a driver supporting JavaScript.
Besides, using `have_current_path` the error message is more readable
when the test fails.
System tests are used to test the application from the user's point of
view. To test for specific exceptions, particularly regarding
authorization permissions, controller tests fit better.
Another option would be to test the page displayed shows a certain text,
like "Internal server error". I'm choosing controller tests because
they're faster and we're basically testing the same scenario many times
and we've already got a test checking what happens when users access a
page raising an exception.
We were repeating the same code over and over (with a few variants) to
setup tests which require an administrator. We can use a tag and
simplify the code.
