Bug 31692: Add Koha::Hold::change_type and unit tests

To test:
1. prove t/db_dependent/Koha/Hold.t

Signed-off-by: David Nind <david@davidnind.com>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Koha/Exceptions/Hold.pm

@@ -23,6 +23,10 @@ use Exception::Class (
     'Koha::Exceptions::Hold' => {
         isa => 'Koha::Exception',
     },
+    'Koha::Exceptions::Hold::CannotChangeHoldType' => {
+        isa         => 'Koha::Exceptions::Hold',
+        description => "Record cannot have both record and item level holds at the same time",
+    },
     'Koha::Exceptions::Hold::CannotSuspendFound' => {
         isa         => 'Koha::Exceptions::Hold',
         description => "Found holds cannot be suspended",

Koha/Hold.pm

@@ -852,6 +852,39 @@ sub fill {
     return $self;
 }
 
+=head3 sub change_type
+
+    $hold->change_type                # to record level
+    $hold->change_type( $itemnumber ) # to item level
+
+Changes hold type between record and item level holds, only if record has
+exactly one hold for a patron. This is because Koha expects all holds for
+a patron on a record to be alike.
+
+=cut
+
+sub change_type {
+    my ( $self, $itemnumber ) = @_;
+
+    my $record_holds_per_patron = Koha::Holds->search( {
+        borrowernumber => $self->borrowernumber,
+        biblionumber => $self->biblionumber,
+    } );
+
+    if ( $itemnumber && $self->itemnumber ) {
+        $self->itemnumber( $itemnumber )->store;
+        return $self;
+    }
+
+    if ( $record_holds_per_patron->count == 1 ) {
+        $self->set({ itemnumber => $itemnumber ? $itemnumber : undef })->store;
+    } else {
+        Koha::Exceptions::Hold::CannotChangeHoldType->throw();
+    }
+
+    return $self;
+}
+
 =head3 store
 
 Override base store method to set default

t/db_dependent/Koha/Hold.t

@@ -997,3 +997,63 @@ subtest 'Koha::Hold::item_group tests' => sub {
 
     $schema->storage->txn_rollback;
 };
+
+subtest 'change_type tests' => sub {
+
+    plan tests => 9;
+
+    $schema->storage->txn_begin;
+
+    my $item = $builder->build_object( { class => 'Koha::Items', } );
+    my $hold = $builder->build_object( {
+        class => 'Koha::Holds',
+        value => {
+            itemnumber => undef,
+        }
+    } );
+
+    my $hold2 = $builder->build_object( {
+        class => 'Koha::Holds',
+        value => {
+            borrowernumber => $hold->borrowernumber,
+        }
+    } );
+
+    ok( $hold->change_type );
+
+    $hold->discard_changes;
+
+    is( $hold->itemnumber, undef, 'record hold to record hold, no changes');
+
+    ok( $hold->change_type( $item->itemnumber ) );
+
+    $hold->discard_changes;
+
+    is( $hold->itemnumber, $item->itemnumber, 'record hold to item hold');
+
+    ok( $hold->change_type( $item->itemnumber ) );
+
+    $hold->discard_changes;
+
+    is( $hold->itemnumber, $item->itemnumber, 'item hold to item hold, no changes');
+
+    ok( $hold->change_type );
+
+    $hold->discard_changes;
+
+    is( $hold->itemnumber, undef, 'item hold to record hold');
+
+    my $hold3 = $builder->build_object( {
+        class => 'Koha::Holds',
+        value => {
+            biblionumber => $hold->biblionumber,
+            borrowernumber => $hold->borrowernumber,
+        }
+    } );
+
+    throws_ok { $hold->change_type }
+        'Koha::Exceptions::Hold::CannotChangeHoldType',
+          'Exception thrown because more than one hold per record';
+
+    $schema->storage->txn_rollback;
+};