Ways of dealing with time in Ruby. These are meant to be alternatives to the many options of constructor/parameter injection of mocked time objects in static languages or ambitious architects.

1_timecop.rb

require 'time'
require 'timecop'

Timecop.freeze Time.parse('1/1/2011')

# All Ruby date functions have been overridden,
# so I can access them in my code directly without 
# constructor or parameter injection.

Time.now # 2011-01-01 00:00:00 -0600

Date.today # <Date: 2011-01-01 ((2455563j,0s,0n),+0s,2299161j)>

# let's return back to the correct date

Timecop.return

Date.today # <Date: 2013-11-26 ((2456623j,0s,0n),+0s,2299161j)>

2_mock_time.rb

require 'mocha/setup'
require 'time'

# I can mock Time.now directly, returning a specific date...
Time.stubs(:now).returns Time.parse('1/1/2011')
Time.now #2011-01-01 00:00:00 -0600

# ... but doing so binds me to one particular way of getting the mocked date/time.
Date.today #<Date: 2013-11-26 ((2456623j,0s,0n),+0s,2299161j)>

# If I'm merely passing the time along to another method or class,
# I can even use an object reference to easily verify that the 
# right value was used.
my_time = Object.new #<Object:0x007fdf7489ed78>
Time.stubs(:now).returns my_time
Time.now #<Object:0x007fdf7489ed78>

3_override_time_directly.rb

# I can even override Time itself, changing its behavior
# for my app.
def Time.now
  1
end

Time.now # 1

# Obviously, I don't do this, but this just shows how
# flexible Ruby can be.