man Test2::Compare::Custom (3): Custom field check for comparisons.

DESCRIPTION

Sometimes you want to do something complicated or unusual when validating a field nested inside a deep data structure. You could pull it out of the structure and test it separately, or you can use this to embed the check. This provides a way for you to write custom checks for fields in deep comparisons.

SYNOPSIS

my $cus = Test2::Compare::Custom->new(
name => 'IsRef',
operator => 'ref(...)',
code => sub {
my ($got, $exists, $operator, $name) = @_;
return ref($got) ? 1 : 0;
},
);
# Pass
is(
{ a => 1, ref => {}, b => 2 },
{ a => 1, ref => $cus, b => 2 },
"This will pass"
);
# Fail
is(
{a => 1, ref => 'notref', b => 2},
{a => 1, ref => $cus, b => 2},
"This will fail"
);

ARGUMENTS

Your custom sub will be passed 4 arguments:

    code => sub {
        my ($got, $exists, $operator, $name) = @_;
        return ref($got) ? 1 : 0;
    },

$_ is also localized to $got to make it easier for those who need to use regexes.

$got
$_: The value to be checked.
$exists: This will be a boolean. This will be true if $got exists at all. If $exists is false then it means $got is not simply undef, but doesn't exist at all (think checking the value of a hash key that does not exist).
$operator: The operator specified at construction.
$name: The name provided at construction.