Assertions for travel_to with attribute-based timezone

Question

At 10 a.m. an object becomes active and visible to the user.
seconds_since_midnight.to_i at 10:00 is 36000, but that is not timezone aware.
application_controller sets a tenant and its timezone, based on one of its attributes

before_action :set_host_shop_timezone

def set_host_shop_timezone
  [...]
  @shop = Shop.find(@site.shop_id)
  Time.zone = @shop.timezone
end

The local (server) is set at GMT +1, while application.rb does not specify any # config.time_zone = 'UTC'

Assertions are needed for:

travel_to Time.zone.local(2025, 8, 8, 9, 59, 58)
travel_to Time.zone.local(2025, 8, 8, 10, 01, 59)

Console confirms:

Time.zone.local(2025, 8, 8, 9, 59, 58).seconds_since_midnight.to_i
=> 35998
Time.zone.local(2025, 8, 8, 10, 01, 59).seconds_since_midnight.to_i
=> 36119

The tests

  test 'time before trip-wire ' do
    @shop = shops(:one)
    travel_to Time.zone.local(2025, 8, 8, 9, 59, 58)
    get root_path, headers: { "host": 'www.one.com' }
    puts Time.zone
    puts Time.zone.local(2025, 8, 8, 9, 59, 58).seconds_since_midnight.to_i
  end

  test 'time after trip-wire ' do
    @shop = shops(:one)
    travel_to Time.zone.local(2025, 8, 8, 10, 00, 12)
    get root_path, headers: { "host": 'www.one.com' }
    puts Time.zone
    puts Time.zone.local(2025, 8, 8, 10, 00, 12).seconds_since_midnight.to_i
  end

return expected results for timezone and seconds since midnight

(GMT+01:00) CET
35998
[...]
(GMT+01:00) CET
36659

but the response.body is wrong in the test (but not in the browser view).
The root_path action intercepts

 puts Time.now
 puts Time.now.seconds_since_midnight.to_i

and returns for each test:

2025-08-08 11:59:58 +0200
43198
[...]
2025-08-08 12:00:12 +0200
43212

with the offset being 2 hours (GMT + summer time).

Where is this test mistaken?

Jerome · Accepted Answer · 2025-11-24 07:55:48Z

Referring to the documentation, the problem can be ascertained through toggling of configuration and adjusting the test.

puts Time.current
    travel_to Time.zone.local(2025, 8, 8, 9, 59, 58)
puts Time.current

setting config.time_zone = 'Rome' the values can be confusing, particularly since data should be stored in UTC format:

2025-11-23 18:36:01 +0100
2025-08-08 09:59:58 +0200

best remain with default # config.time_zone = 'UTC'. The test will show:

2025-11-23 18:02:37 UTC
2025-08-08 09:59:58 UTC

Thus the issue is travel_to travels to the time of the application's timezone, not that of the tenant.

setting the timezone in the application controller is moot . The instruction is pointless clutter and be removed # Time.zone = @shop.timezone. What matters is that the logic take into account the offset to UTC. Thus two travels are required:

  puts Time.current
travel_to Time.zone.local(2025, 8, 8, 9, 59, 58)
  puts Time.current
offset = 0 - Time.now.utc_offset
  puts offset
travel offset.seconds
  puts Time.current

utc_offset must be set to negative: Berlin? ahead => positive utc_offset, need to subtract. New York? behind => negative utc_offset, need to add.
The result is what is needed to conduct the test:

2025-11-23 19:02:26 UTC
2025-08-08 09:59:58 UTC
-7200
2025-08-08 07:59:58 UTC

Two travels:

travel_to Time.zone.local(2025, 8, 8, 10, 00, 12)
offset = 0 - Time.now.utc_offset
travel offset.seconds

Recommended testing: play around with different fixture values for @shop.timezone & dates that straddle summer & winter time creating gap weeks (i.e. NAmerica & Europe in late march and october).

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