Exercism

Instructions

Test suite

Solution

Clean up user-entered phone numbers so that they can be sent SMS messages.

The North American Numbering Plan (NANP) is a telephone numbering system used by many countries in North America like the United States, Canada or Bermuda. All NANP-countries share the same international country code: 1.

NANP numbers are ten-digit numbers consisting of a three-digit Numbering Plan Area code, commonly known as area code, followed by a seven-digit local number. The first three digits of the local number represent the exchange code, followed by the unique four-digit number which is the subscriber number.

The format is usually represented as

(NXX)-NXX-XXXX

where N is any digit from 2 through 9 and X is any digit from 0 through 9.

Your task is to clean up differently formatted telephone numbers by removing punctuation and the country code (1) if present.

For example, the inputs

+1 (613)-995-0253
613-995-0253
1 613 995 0253
613.995.0253

should all produce the output

6139950253

Note: As this exercise only deals with telephone numbers used in NANP-countries, only 1 is considered a valid country code.

For installation and learning resources, refer to the Ruby resources 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 phone_number_test.rb

To include color from the command line:

ruby -r minitest/pride phone_number_test.rb

Source

Event Manager by JumpstartLab http://tutorials.jumpstartlab.com/projects/eventmanager.html

Submitting Incomplete Solutions

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

phone_number_test.rb

require 'minitest/autorun'
require_relative 'phone_number'

# Common test data version: 1.6.0 a317aa4
class PhoneNumberTest < Minitest::Test
  def test_cleans_the_number
    # skip
    assert_equal "2234567890", PhoneNumber.clean("(223) 456-7890")
  end

  def test_cleans_numbers_with_dots
    skip
    assert_equal "2234567890", PhoneNumber.clean("223.456.7890")
  end

  def test_cleans_numbers_with_multiple_spaces
    skip
    assert_equal "2234567890", PhoneNumber.clean("223 456   7890   ")
  end

  def test_invalid_when_9_digits
    skip
    assert_nil PhoneNumber.clean("123456789")
  end

  def test_invalid_when_11_digits_does_not_start_with_a_1
    skip
    assert_nil PhoneNumber.clean("22234567890")
  end

  def test_valid_when_11_digits_and_starting_with_1
    skip
    assert_equal "2234567890", PhoneNumber.clean("12234567890")
  end

  def test_valid_when_11_digits_and_starting_with_1_even_with_punctuation
    skip
    assert_equal "2234567890", PhoneNumber.clean("+1 (223) 456-7890")
  end

  def test_invalid_when_more_than_11_digits
    skip
    assert_nil PhoneNumber.clean("321234567890")
  end

  def test_invalid_with_letters
    skip
    assert_nil PhoneNumber.clean("123-abc-7890")
  end

  def test_invalid_with_punctuations
    skip
    assert_nil PhoneNumber.clean("123-@:!-7890")
  end

  def test_invalid_if_area_code_starts_with_0
    skip
    assert_nil PhoneNumber.clean("(023) 456-7890")
  end

  def test_invalid_if_area_code_starts_with_1
    skip
    assert_nil PhoneNumber.clean("(123) 456-7890")
  end

  def test_invalid_if_exchange_code_starts_with_0
    skip
    assert_nil PhoneNumber.clean("(223) 056-7890")
  end

  def test_invalid_if_exchange_code_starts_with_1
    skip
    assert_nil PhoneNumber.clean("(223) 156-7890")
  end

  def test_invalid_if_area_code_starts_with_0_on_valid_11_digit_number
    skip
    assert_nil PhoneNumber.clean("1 (023) 456-7890")
  end

  def test_invalid_if_area_code_starts_with_1_on_valid_11_digit_number
    skip
    assert_nil PhoneNumber.clean("1 (123) 456-7890")
  end

  def test_invalid_if_exchange_code_starts_with_0_on_valid_11_digit_number
    skip
    assert_nil PhoneNumber.clean("1 (223) 056-7890")
  end

  def test_invalid_if_exchange_code_starts_with_1_on_valid_11_digit_number
    skip
    assert_nil PhoneNumber.clean("1 (223) 156-7890")
  end
end

class PhoneNumber
  def self.clean(input)
    new(input).valid_number
  end

  def initialize(input)
    @phone_number = input
  end

  def valid_number
    remove_nondigits
    remove_leading_one
    phone_number if valid?
  end

  private

  attr_reader :phone_number

  def valid?
    phone_number.length == 10 && area_code_valid? && exchange_code_valid?
  end

  def area_code_valid?
    phone_number[0].match?(/[2-9]/)
  end

  def exchange_code_valid?
    phone_number[3].match?(/[2-9]/)
  end

  def remove_nondigits
    @phone_number.gsub!(/\D/, '')
  end

  def remove_leading_one
    @phone_number.gsub!(/^1/, '')
  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?

PatrickMcSweeny's solution

to Phone Number in the Ruby Track

Source

Submitting Incomplete Solutions

phone_number_test.rb

What can you learn from this solution?