We might need to setup a prelude for initialising a file in the
filesystem for testing here - not only does stream_test_file need it,
but I see later tests requiring an equivalence check for files and
strings (variants of a stream).
While the previous method of in-lining a stack allocated array of
tests into the suite struct declaration was nice, we had to update
size manually.
This macro will allow us to just append new tests to the suite without
having to care for that. It generates a uniquely named variable for
the test array, then uses that test array in the suite declaration.
Nice and easy.
