+my $cal = Koha::Calendar->new( TEST_MODE => 1 );
+
+isa_ok( $cal, 'Koha::Calendar' );
+
+my $test_dt = DateTime->new( # Monday
+ year => 2012,
+ month => 7,
+ day => 23,
+ hour => 11,
+ minute => 53,
+ time_zone => 'Europe/London',
+);
+
+my $later_dt = DateTime->new( # Monday
+ year => 2012,
+ month => 9,
+ day => 17,
+ hour => 17,
+ minute => 30,
+ time_zone => 'Europe/London',
+);
+
+my $daycount = $cal->days_between( $test_dt, $later_dt );
+cmp_ok( $daycount->in_units('days'),
+ '==', 48, 'days_between calculates correctly' );
+
+my $ret = $cal->addDate( $test_dt, 1, 'days' );
+
+cmp_ok( $ret->ymd(), 'eq', '2012-07-24', 'Simple Single Day Add (Calendar)`' );
+
+$ret = $cal->addDate( $test_dt, 7, 'days' );
+cmp_ok( $ret->ymd(), 'eq', '2012-07-31', 'Add 7 days Calendar mode' );
+$cal->set_daysmode('Datedue');
+$ret = $cal->addDate( $test_dt, 7, 'days' );
+cmp_ok( $ret->ymd(), 'eq', '2012-07-30', 'Add 7 days Datedue mode' );
+$cal->set_daysmode('Days');
+$ret = $cal->addDate( $test_dt, 7, 'days' );
+cmp_ok( $ret->ymd(), 'eq', '2012-07-30', 'Add 7 days Days mode' );
+$cal->set_daysmode('Calendar');
+
+# example tests for bug report
+$cal->clear_weekly_closed_days();
+
+$daycount = $cal->days_between( dt_from_string('2012-01-10'),
+ dt_from_string("2012-05-05") )->in_units('days');
+cmp_ok( $daycount, '==', 116, 'test larger intervals' );
+$daycount = $cal->days_between( dt_from_string("2012-01-01"),
+ dt_from_string("2012-05-05") )->in_units('days');
+cmp_ok( $daycount, '==', 125, 'test positive intervals' );
+my $daycount2 = $cal->days_between( dt_from_string("2012-05-05"),
+ dt_from_string("2012-01-01") )->in_units('days');
+cmp_ok( $daycount2, '==', $daycount, 'test parameter order not relevant' );
+$daycount = $cal->days_between( dt_from_string("2012-07-01"),
+ dt_from_string("2012-07-15") )->in_units('days');
+cmp_ok( $daycount, '==', 14, 'days_between calculates correctly' );
+$cal->add_holiday( dt_from_string('2012-07-06') );
+$daycount = $cal->days_between( dt_from_string("2012-07-01"),
+ dt_from_string("2012-07-15") )->in_units('days');
+cmp_ok( $daycount, '==', 13, 'holiday correctly recognized' );
+
+$cal->add_holiday( dt_from_string('2012-07-07') );
+$daycount = $cal->days_between( dt_from_string("2012-07-01"),
+ dt_from_string("2012-07-15") )->in_units('days');
+cmp_ok( $daycount, '==', 12, 'multiple holidays correctly recognized' );