Ruby TZInfo and Rails ActiveSupport::Timezone UTC_offset differences

Question

I want to find the total UTC offset from a Timezone Object. Below are two examples using TZInfo::Timezone and ActiveSupport::TimeZone . Ultimately, I want to use the ActiveSupport::TimeZone implementation, but can't get it to give me the right answer.

#TZInfo implementation
tz = TZInfo::Timezone.get('America/New_York')
tz.current_period.utc_total_offset / 60 / 60
=> -4 (CORRECT)

# Rails implementation
tz = ActiveSupport::TimeZone.new("Eastern Time (US & Canada)")
tz.utc_offset / 60 / 60
=> -5 (WRONG)

Why does ActiveSupport::TimeZone appear to fail to factor in dst? How do I fix that?

Answer 1

I found this in the ActiveSupport documentation . Basically, it is running tzinfo.current_period.utc_offset instead of tzinfo.current_period.utc_total_offset

def utc_offset
  if @utc_offset
    @utc_offset
  else
    tzinfo.current_period.utc_offset if tzinfo && tzinfo.current_period
  end
end

So to fully answer my question: I need the following code...

tz = ActiveSupport::TimeZone.new("Eastern Time (US & Canada)")
tz.tzinfo.current_period.utc_total_offset / 60 / 60