Schedule losing timezone when serialized with ical

[Rockster160]

Ruby 2.3.1
Rails 5.0.2
IceCube 0.16.2

schedule = IceCube::Schedule.new(Time.now.in_time_zone(-6))
=> #<IceCube::Schedule:0x005592aed59940 @start_time=Fri, 23 Mar 2018 19:53:42 CST -06:00, @all_recurrence_rules=[], @all_exception_rules=[]>
> schedule.start_time
=> Fri, 23 Mar 2018 19:53:42 CST -06:00
> IceCube::Schedule.from_ical(schedule.to_ical).start_time
=> 2018-03-23 19:53:42 +0000

Notice it goes from 7:53 PM CST to 7:53 PM UTC - losing the accuracy of the time as well as dropping the time zone.

[hbhanoo]

I just noticed this too!

[sergioisidoro]

I'm having the opposite issue (de-serialization, not serialization)

> schedule = IceCube::Schedule.new(Time.current)
{
    :start_time => {
        :time => 2025-06-17 15:06:35.246698923 UTC,
        :zone => "Europe/Helsinki"
    },
        :rrules => [],
        :rtimes => [],
       :extimes => []
}

> rule = IceCube::Rule.daily(1000).day_of_week(tuesday: [1, -1], wednesday: [2])
> schedule.add_recurrence_rule(rule)
> ical_string = schedule.to_ical
"DTSTART;TZID=EEST:20250617T180635\nRRULE:FREQ=DAILY;INTERVAL=1000;BYDAY=1TU,-1TU,2WE"

> ice_cube = IceCube::Schedule.from_ical(ical_string)
{
    :start_time => 2025-06-17 18:06:35 +0000,
    ...
}

Serialization is working with timezones, and string is correctly generated. But when I do from_ical it defaults to UTC and loses timezone (note that 18:06:35 +0000 should actually be 15:06:35 UTC or 18:06:35 EEST)

Edit: found something very interesting in the specs of RFC2445:

The TZID property parameter MUST NOT be applied to DATE-TIME or TIME
properties whose time values are specified in UTC.

However we see that the time string is being serialized to :20250617T180635 which is in local time. There ical_format(time, force_utc), which If i read things correctly should ALWAYS be UTC.