```ruby
begin
  require 'simplecov'
  SimpleCov.start
rescue LoadError
  # okay
end

require File.dirname(__FILE__) + '/../lib/ice_cube'

DAY = Time.utc(2010, 3, 1)
WEDNESDAY = Time.utc(2010, 6, 23, 5, 0, 0)

RSpec.configure do |config|

  config.around :each, :if_active_support_time => true do |example|
    example.run if defined? ActiveSupport::Time
  end

  config.around :each, :if_active_support_time => false do |example|
    example.run unless defined? ActiveSupport::Time
  end

end
```

Add helper for system environment TZ testing
user
```ruby
begin
  require 'simplecov'
  SimpleCov.start
rescue LoadError
  # okay
end

require File.dirname(__FILE__) + '/../lib/ice_cube'

DAY = Time.utc(2010, 3, 1)
WEDNESDAY = Time.utc(2010, 6, 23, 5, 0, 0)
WORLD_TIME_ZONES = [
  'Pacific/Midway',     # -1100
  'America/Adak',       # -1000 / -0900
  'Europe/London',      # +0000 / +0100
  'Pacific/Wellington', # +1200 / +1300
  'Pacific/Fiji'        # +1200
]

RSpec.configure do |config|

  config.around :each, :if_active_support_time => true do |example|
    example.run if defined? ActiveSupport::Time
  end

  config.around :each, :if_active_support_time => false do |example|
    example.run unless defined? ActiveSupport::Time
  end

  config.around :each do |example|
    if zone = example.metadata[:system_time_zone]
      @orig_zone = ENV['TZ']
      ENV['TZ'] = zone
      example.run
      ENV['TZ'] = @orig_zone
    else
      example.run
    end
  end

  config.before :each do
    if time_args = @example.metadata[:system_time]
      case time_args
      when Array then Time.stub!(:now).and_return Time.local(*time_args)
      when Time  then Time.stub!(:now).and_return time_args
      end
    end
  end
end
```
assistant