Test2::Compare::Base - Base class for comparison classes.


All comparison classes for Test2::Compare should inherit from this base class.


    package Test2::Compare::MyCheck;
    use strict;
    use warnings;
    use base 'Test2::Compare::Base';
    use Test2::Util::HashBase qw/stuff/;
    sub name { 'STUFF' }
    sub operator {
        my $self = shift;
        my ($got) = @_;
        return 'eq';
    sub verify {
        my $self = shift;
        my $params = @_;
        # Always check if $got exists! This method must return false if no
        # value at all was received.
        return 0 unless $params{exists};
        my $got = $params{got};
        # Returns true if both values match. This includes undef, 0, and other
        # false-y values!
        return $got eq $self->stuff;


Some of these must be overridden, others can be.

$dclass = $check->delta_class

Returns the delta subclass that should be used. By default Test2::Compare::Delta is used.

@deltas = $check->deltas(id => $id, exists => $bool, got => $got, convert => \&convert, seen => \%seen)

Should return child deltas.

@lines = $check->got_lines($got)

This is your chance to provide line numbers for errors in the $got structure.

$op = $check->operator()
$op = $check->operator($got)

Returns the operator that was used to compare the check with the received data in $got. If there was no value for got then there will be no arguments, undef will only be an argument if undef was seen in $got. This is how you can tell the difference between a missing value and an undefined one.

$bool = $check->verify(id => $id, exists => $bool, got => $got, convert => \&convert, seen => \%seen)

Return true if there is a shallow match, that is both items are arrayrefs, both items are the same string or same number, etc. This should not recurse, as deep checks are done in $check->deltas().

$name = $check->name

Get the name of the check.

$display = $check->render

What should be displayed in a table for this check, usually the name or value.

$delta = $check->run(id => $id, exists => $bool, got => $got, convert => \&convert, seen => \%seen)

This is where the checking is done, first a shallow check using $check->verify, then checking $check->deltas(). \%seen is used to prevent cycles.


The source code repository for Test2-Suite can be found at


Chad Granum <>


Chad Granum <>


Copyright 2016 Chad Granum <>.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.