Checking the database with methods like Activity.last does not test that
the record is present where it should be (first record of the table in
this case). In these tests there's only one record, though, so the order
doesn't matter that match.
However, calling methods like Activity.last generates a database query
after the process running the browser has been started, and this might
lead to inconsistent data.
JavaScript is used by about 98% of web users, so by testing without it
enabled, we're only testing that the application works for a very
reduced number of users.
We proceeded this way in the past because CONSUL started using Rails 4.2
and truncating the database between JavaScript tests with database
cleaner, which made these tests terribly slow.
When we upgraded to Rails 5.1 and introduced system tests, we started
using database transactions in JavaScript tests, making these tests much
faster. So now we can use JavaScript tests everywhere without critically
slowing down our test suite.
