Timezone problem when casting time field

[bvicenzo]

Steps to reproduce

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails", branch: "main"
end

require "active_support"
require "active_support/core_ext/object/blank"
require "minitest/autorun"

class BugTest < Minitest::Test
  def test_time_zone
    Time.zone = 'Brasilia'
    assert Time.zone.local(2007, 2, 10, 15, 30, 45).to_s.end_with?('-0300')
    assert Time.zone.parse('2007-02-10 15:30:45').to_s.end_with?('-0300')
    assert Time.zone.at(1171139445).to_s.end_with?('-0300')
    assert Time.zone.now.to_s.end_with?('-0300')
    assert Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone.to_s.end_with?('-0300')
  end
end

Expected behavior

Looking for TimeWithZone doc, I understood that this should return time in the defined timezone.

Time.zone = 'Eastern Time (US & Canada)'        # => 'Eastern Time (US & Canada)'
Time.zone.local(2007, 2, 10, 15, 30, 45)        # => Sat, 10 Feb 2007 15:30:45.000000000 EST -05:00
Time.zone.parse('2007-02-10 15:30:45')          # => Sat, 10 Feb 2007 15:30:45.000000000 EST -05:00
Time.zone.at(1171139445)                        # => Sat, 10 Feb 2007 15:30:45.000000000 EST -05:00
Time.zone.now                                   # => Sun, 18 May 2008 13:07:55.754107581 EST -05:00
Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone  # => Sat, 10 Feb 2007 15:30:45.000000000 EST -05:00

Actual behavior

However, what I see is Time.zone.now returning a different timezone from others. As docs.

Shouldn't they all return the same timezone?

I realized that when I'm using a time field and it started to show my time aways 1 hour ahead.
And I saw that is uses Time.local to cast:

rails/activemodel/lib/active_model/type/helpers/time_value.rb

Line 61 in 3258979

::Time.local(year, mon, mday, hour, min, sec, microsec) rescue nil

It seems that all methods, except Time.zone.now are using brazilian summer time instead of use brazilian time.

System configuration

Rails version: 7.0.3.1

Ruby version: 3.0.3p157 (2021-11-24 revision 3fb7d2cadc) [x86_64-linux-musl]

[hbontempo-br]

Hi @bvicenzo!

I know this is strange and confusing, but the behavior is correct.
The normal timezone for Brazil is -03:00, but in 2007-02-10 Brazil was in the -02:00 timezone because in this date Brazil was using a DST (summer time).

Source: https://pt.wikipedia.org/wiki/Lista_de_per%C3%ADodos_em_que_vigorou_o_horário_de_verão_no_Brasil

[bvicenzo]

Hi @hbontempo-br!

Thanks for the answer.

That's true!!!

Then I realized what would be happening to me...

As I said before, I'm using a time field, and before, and it casts the value to a date time field:

ActiveModel::Type::Time.new.cast('10:00') # => 2000-01-01 10:00:00 -0200

And this could confuse me. I'll keep investigating my problem.

Thanks again.