t/pugs/operator/arith.t

Jesse asked about getting t/pugs/operator/arith.t to run
on Rakudo, as written arith.t depends on the ".nextwith"
capability from S06.  For example:

sub tryok ($ok, $todo) {
if ($todo) {
&ok.nextwith($ok,$todo, :todo);
} else {
&ok.nextwith($ok);
}
}

I'm of the opinion that we shouldn't require .nextwith to
be implemented for testing something basic like arithmetics,
so if we keep the above I propose changing &ok.nextwith() to
ok() calls for now.

In general, I think that tests should only need a rather
limited set of functions and Perl 6 features, and something
like .nextwith seems to fall outside of that.  So as far
as we can, I think the test suite ought to stick to things
like:

ok($cond)
ok($cond, $desc)

is($got, $expected)
is($got, $expected, $desc)

isnt($got, $expected)
isnt($got, $expected, $desc)

is_approx($got, $expected)
is_approx($got, $expected, $desc)

Note that in the test suite 'todo' and 'skip' are often
handled by fudge as opposed to being an optional argument
to ok().

In the case of arith.t, I don't quite see the need for
the tryok() definition and tryeq().  It seems that it
would be much cleaner and more consistent for arith.t
to use

is           13 %  4, 1;
is          -13 %  4, 3;
is_approx    13e21 % 4e21 - 1e21, 0;
is_approx   -13e21 % 4e21 - 3e21, 0;

instead of

tryeq  13 %  4, 1;
tryeq -13 %  4, 3;
tryok abs( 13e21 %  4e21 -  1e21) < $limit;
tryok abs(-13e21 %  4e21 -  3e21) < $limit;

and locally defined try* subs.  (There's also the point
that 'try' is a keyword in Perl 6, and 'tryeq' and 'tryok'
don't seem to have anything obvious to do with that 'try'.)

Pm