All of the constants that you have used so far
you have put into Constants.swift.
It would have been technically possible to add each of these constants
to the top of the test file that you used them in.
However, as you have already seen,
it is quite common to use the same constants
in multiple tests and in multiple test files.
On the one hand, if you do not put constants in the files
where they are first used,
they will be visible from other test files –
so long as you do not mark them
On the other hand, if you follow this approach,
your shared constants will be scattered throughout your test files
and harder to track down.
For this reason, stylish Swift programmers put their shared test constants into a ...