Sample implementation of http://yuji-shimoda.hatenablog.com/entry/2013/04/26/001951
# in irb or pry
> require './calendar_renderer'
> puts CalendarRenderer.new(2013,1).to_s
January 2013
Su Mo Tu We Th Fr Sa
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
$ rspec --color calendar_renderer_spec.rb