# paulfioravanti's solution

## to Gigasecond in the Elixir Track

Published at Jun 19 2019 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

Calculate the moment when someone has lived for 10^9 seconds.

A gigasecond is 10^9 (1,000,000,000) seconds.

## Running tests

Execute the tests with:

``````\$ elixir gigasecond_test.exs
``````

### Pending tests

In the test suites, all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.

For example:

``````# @tag :pending
test "shouting" do
assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end
``````

Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the test suite.

``````# ExUnit.configure exclude: :pending, trace: true
``````

If you're stuck on something, it may help to look at some of the available resources out there where answers might be found.

## 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.exs

``````if !System.get_env("EXERCISM_TEST_EXAMPLES") do
Code.load_file("gigasecond.exs", __DIR__)
end

ExUnit.start()
ExUnit.configure(exclude: :pending, trace: true)

defmodule GigasecondTest do
use ExUnit.Case

# @tag :pending
test "from 4/25/2011" do
assert Gigasecond.from({{2011, 4, 25}, {0, 0, 0}}) == {{2043, 1, 1}, {1, 46, 40}}
end

@tag :pending
test "from 6/13/1977" do
assert Gigasecond.from({{1977, 6, 13}, {0, 0, 0}}) == {{2009, 2, 19}, {1, 46, 40}}
end

@tag :pending
test "from 7/19/1959" do
assert Gigasecond.from({{1959, 7, 19}, {0, 0, 0}}) == {{1991, 3, 27}, {1, 46, 40}}
end

@tag :pending
test "yourself" do
# customize these values for yourself
# your_birthday = {{year1, month1, day1}, {0, 0, 0}}
# assert Gigasecond.from(your_birthday) == {{year2, month2, day2}, {hours, minutes, seconds}}
end
end``````
``````defmodule Gigasecond do
@seconds :math.pow(10, 9)
|> round()

@doc """
Calculate a date one billion seconds after an input date.
"""
@spec from(
{{pos_integer, pos_integer, pos_integer},
{pos_integer, pos_integer, pos_integer}}
) ::
:calendar.datetime()

def from(erl_datetime) do
erl_datetime
|> NaiveDateTime.from_erl!()
|> NaiveDateTime.add(@seconds)
|> NaiveDateTime.to_erl()
end
end``````

## Community comments

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### What can you learn from this solution?

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