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Instructions
Test Suite
Solution

# Gigasecond

Calculate the moment when someone has lived for 109 seconds.

A gigasecond is 109 (1,000,000,000) seconds.

For installation and learning resources, refer to the exercism help page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

``````gem install minitest
``````

If you would like color output, you can `require 'minitest/pride'` in the test file, or note the alternative instruction, below, for running the test file.

Run the tests from the exercise directory using the following command:

``````ruby gigasecond_test.rb
``````

To include color from the command line:

``````ruby -r minitest/pride gigasecond_test.rb
``````

## Source

Chapter 9 in Chris Pine's online Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=09

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### gigasecond_test.rb

``````require 'minitest/autorun'
require_relative 'gigasecond'

# Common test data version: 1.0.0 61e7d70
class GigasecondTest < Minitest::Test
def test_date_only_specification_of_time
# skip
assert_equal Time.utc(2043, 1, 1, 1, 46, 40), Gigasecond.from(Time.utc(2011, 4, 25, 0, 0, 0))
end

def test_second_test_for_date_only_specification_of_time
skip
assert_equal Time.utc(2009, 2, 19, 1, 46, 40), Gigasecond.from(Time.utc(1977, 6, 13, 0, 0, 0))
end

def test_third_test_for_date_only_specification_of_time
skip
assert_equal Time.utc(1991, 3, 27, 1, 46, 40), Gigasecond.from(Time.utc(1959, 7, 19, 0, 0, 0))
end

def test_full_time_specified
skip
assert_equal Time.utc(2046, 10, 2, 23, 46, 40), Gigasecond.from(Time.utc(2015, 1, 24, 22, 0, 0))
end

def test_full_time_with_day_roll_over
skip
assert_equal Time.utc(2046, 10, 3, 1, 46, 39), Gigasecond.from(Time.utc(2015, 1, 24, 23, 59, 59))
end

# Problems in exercism evolve over time, as we find better ways to ask
# questions.
# The version number refers to the version of the problem you solved,
#
# Define a constant named VERSION inside of the top level BookKeeping
# module, which may be placed near the end of your file.
#
# In your file, it will look like this:
#
# module BookKeeping
#   VERSION = 1 # Where the version number matches the one in the test.
# end
#
# http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html

def test_bookkeeping
skip
assert_equal 6, BookKeeping::VERSION
end
end``````
``````class Gigasecond
ONE_GIGASECOND = 10**9

def self.from(date)
(date.to_time + ONE_GIGASECOND).to_date
end
end``````

### What can you learn from this solution?

A huge amount can be learnt from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

• What compromises have been made?
• Are there new concepts here that I could read more about to develop my understanding?

over 3 years ago

@sprunger thanks so I tried removing to_time and to_date, thinking that when I added ONE_GIGASECOND to date, ruby might stick with the date convention but this didn't work. Could you elaborate?

here's what didn't work:
(date + ONE_GIGASECOND)

over 3 years ago
sprunger says

Looks good! Did you know that Ruby is pretty good at using convention, meaning you only need to specify unconventional aspects. See what happens when you just add a number to a Date.

over 3 years ago