Bug 13098: Add Koha::Account::Offsets->total

This patch introduces this trivial method for returning the sum0 result
of the amount columns of a Koha::Account::Offsets set.

To test:
- Apply this patch
- Run:
  $ kshell
 k$ prove t/db_dependent/Koha/Account/Offsets.t
- Sign off :-D

Followed test plan, patch worked as described
Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>

Koha/Account/Offsets.pm

@@ -18,6 +18,7 @@ package Koha::Account::Offsets;
 use Modern::Perl;
 
 use Carp;
+use List::Util qw(sum0);
 
 use Koha::Database;
 
@@ -33,6 +34,20 @@ Account offsets track the changes made to the balance of account lines
 
 =head1 API
 
+=head2 Class methods
+
+=head3 total
+
+=cut
+
+sub total {
+    my ( $self ) = @_;
+
+    my $total = sum0( $self->get_column('amount') );
+
+    return $total;
+}
+
 =head2 Internal methods
 
 =head3 _type

t/db_dependent/Koha/Account/Offsets.t

@@ -0,0 +1,70 @@
+#!/usr/bin/perl
+
+# Copyright 2018 Koha Development team
+#
+# This file is part of Koha
+#
+# Koha is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# Koha is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with Koha; if not, see <http://www.gnu.org/licenses>
+
+use Modern::Perl;
+
+use Test::More tests => 1;
+use Test::Exception;
+
+use Koha::Account::Offsets;
+
+use t::lib::TestBuilder;
+
+my $schema  = Koha::Database->new->schema;
+my $builder = t::lib::TestBuilder->new;
+
+subtest 'total_outstanding() tests' => sub {
+
+    plan tests => 4;
+
+    $schema->storage->txn_begin;
+
+    my $line = $builder->build_object( { class => 'Koha::Account::Lines' } );
+
+    my $amount_1 = 100;
+    my $amount_2 = 200;
+    my $amount_3 = -100;
+    my $amount_4 = -300;
+    my $amount_5 = 500;
+
+    my $offset_1 = Koha::Account::Offset->new(
+        { type => 'Fine', amount => $amount_1, credit_id => $line->id } )->store;
+    my $offset_2 = Koha::Account::Offset->new(
+        { type => 'Fine', amount => $amount_2, credit_id => $line->id } )->store;
+    my $offset_3 = Koha::Account::Offset->new(
+        { type => 'Payment', amount => $amount_3, credit_id => $line->id } )->store;
+    my $offset_4 = Koha::Account::Offset->new(
+        { type => 'Payment', amount => $amount_4, credit_id => $line->id } )->store;
+    my $offset_5 = Koha::Account::Offset->new(
+        { type => 'Fine', amount => $amount_5, credit_id => $line->id } )->store;
+
+    my $debits = Koha::Account::Offsets->search( { type => 'Fine', credit_id => $line->id } );
+    is( $debits->total, $amount_1 + $amount_2 + $amount_5 );
+
+    my $credits = Koha::Account::Offsets->search( { type => 'Payment', credit_id => $line->id } );
+    is( $credits->total, $amount_3 + $amount_4 );
+
+    my $all = Koha::Account::Offsets->search( { credit_id => $line->id } );
+    is( $all->total, $amount_1 + $amount_2 + $amount_3 + $amount_4 + $amount_5 );
+
+    my $none = Koha::Account::Offsets->search( { credit_id => $line->id + 1 } );
+    is( $none->total, 0, 'No offsets, returns 0' );
+
+    $schema->storage->txn_rollback;
+};