ActiveSupport::Testing::TimeHelpers

Contains helpers that help you test passage of time.

Methods
T
Instance Public methods
travel(duration, &block)

Changes current time to the time in the future or in the past by a given time difference by stubbing Time.now, Date.today, and DateTime.now.

Time.current     # => Sat, 09 Nov 2013 15:34:49 EST -05:00
travel 1.day
Time.current     # => Sun, 10 Nov 2013 15:34:49 EST -05:00
Date.current     # => Sun, 10 Nov 2013
DateTime.current # => Sun, 10 Nov 2013 15:34:49 -0500

This method also accepts a block, which will return the current time back to its original state at the end of the block:

Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
travel 1.day do
  User.create.created_at # => Sun, 10 Nov 2013 15:34:49 EST -05:00
end
Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00

Source: show | on GitHub 

# File activesupport/lib/active_support/testing/time_helpers.rb, line 69
def travel(duration, &block)
  travel_to Time.now + duration, &block
end
travel_back()

Returns the current time back to its original state, by removing the stubs added by `travel` and `travel_to`.

Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
travel_to Time.zone.local(2004, 11, 24, 01, 04, 44)
Time.current # => Wed, 24 Nov 2004 01:04:44 EST -05:00
travel_back
Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00

Source: show | on GitHub 

# File activesupport/lib/active_support/testing/time_helpers.rb, line 159
def travel_back
  simple_stubs.unstub_all!
end
travel_to(date_or_time)

Changes current time to the given time by stubbing Time.now, Date.today, and DateTime.now to return the time or date passed into this method.

Time.current     # => Sat, 09 Nov 2013 15:34:49 EST -05:00
travel_to Time.zone.local(2004, 11, 24, 01, 04, 44)
Time.current     # => Wed, 24 Nov 2004 01:04:44 EST -05:00
Date.current     # => Wed, 24 Nov 2004
DateTime.current # => Wed, 24 Nov 2004 01:04:44 -0500

Dates are taken as their timestamp at the beginning of the day in the application time zone. Time.current returns said timestamp, and Time.now its equivalent in the system time zone. Similarly, Date.current returns a date equal to the argument, and Date.today the date according to Time.now, which may be different. (Note that you rarely want to deal with Time.now, or Date.today, in order to honor the application time zone please always use Time.current and Date.current.)

Note that the usec for the time passed will be set to 0 to prevent rounding errors with external services, like MySQL (which will round instead of floor, leading to off-by-one-second errors).

This method also accepts a block, which will return the current time back to its original state at the end of the block:

Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00
travel_to Time.zone.local(2004, 11, 24, 01, 04, 44) do
  Time.current # => Wed, 24 Nov 2004 01:04:44 EST -05:00
end
Time.current # => Sat, 09 Nov 2013 15:34:49 EST -05:00

Source: show | on GitHub 

# File activesupport/lib/active_support/testing/time_helpers.rb, line 103
      def travel_to(date_or_time)
        if block_given? && simple_stubs.stubbing(Time, :now)
          travel_to_nested_block_call = "
      Calling `travel_to` with a block, when we have previously already made a call to `travel_to`, can lead to confusing time stubbing.

      Instead of:

         travel_to 2.days.from_now do
           # 2 days from today
           travel_to 3.days.from_now do
             # 5 days from today
           end
         end

      preferred way to achieve above is:

         travel 2.days do
           # 2 days from today
         end

         travel 5.days do
           # 5 days from today
         end

".strip_heredoc
          raise travel_to_nested_block_call
        end

        if date_or_time.is_a?(Date) && !date_or_time.is_a?(DateTime)
          now = date_or_time.midnight.to_time
        else
          now = date_or_time.to_time.change(usec: 0)
        end

        simple_stubs.stub_object(Time, :now) { at(now.to_i) }
        simple_stubs.stub_object(Date, :today) { jd(now.to_date.jd) }
        simple_stubs.stub_object(DateTime, :now) { jd(now.to_date.jd, now.hour, now.min, now.sec, Rational(now.utc_offset, 86400)) }

        if block_given?
          begin
            yield
          ensure
            travel_back
          end
        end
      end