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angelikatyborska's solution

to Phone Number in the Ruby Track

Published at Jul 13 2018 · 2 comments
Instructions
Test suite
Solution

Note:

This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code was written.

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 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 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: 1.2.0 39cba0d
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_does_not_start_with_2_9
    skip
    assert_nil PhoneNumber.clean("(123) 456-7890")
  end

  def test_invalid_if_exchange_code_does_not_start_with_2_9
    skip
    assert_nil PhoneNumber.clean("(223) 056-7890")
  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,
  # not your solution.
  #
  # 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
  #
  # If you are curious, read more about constants on RubyDoc:
  # http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html

  def test_bookkeeping
    skip
    assert_equal 2, BookKeeping::VERSION
  end
end
class PhoneNumber
  def initialize(string)
    @number = self.class.valid_phone_number?(string) ? self.class.sanitize(string) : 0
  end

  def number
    "#{format('%010d', @number)}"
  end

  def area_code
    number[0..2]
  end

  def core_number
    number[3..9]
  end

  def to_s
    "(#{ area_code }) #{ core_number[0..2] }-#{ core_number[3..6] }"
  end

  class << self
    def valid_phone_number?(string)
      regexp.match(string)
    end

    def sanitize(phone_number)
      with_digits_only = remove_non_digits(phone_number)
      trim_country_code(with_digits_only)
    end

    private

    # Matches phone numbers from the USA, examples:
    # 5556667777
    # (555) 666-7777
    # +1 555 666 7777
    # (+1.555).666.7777
    def regexp
      delimiter = '[\.\-\s]?'
      prefix = '\(?\+?1?' + delimiter + '\d{3}\)?'
      Regexp.new('\A' + prefix + delimiter + '\d{3}' + delimiter + '\d{4}\z')
    end

    def remove_non_digits(phone_number)
      phone_number.gsub(/\D/, '')
    end

    def trim_country_code(phone_number)
      length_with_country_code = 11
      starting_index = phone_number.length == length_with_country_code ? 1 : 0
      phone_number[starting_index..-1]
    end
  end
end

Community comments

Find this solution interesting? Ask the author a question to learn more.
Avatar of angelikatyborska

When I first wrote the method to_s like so def to_s "(#{ area_code }) #{ number[0..2] }-#{ number[3..6] }" end

I felt like I was mixing two levels of abstraction, so to make things even I introduced the core_number method.

I really wanted the sanitize method to be private, because I don't feel that it should be a part of the public interface, but, as I found out, in Ruby you can't call private class methods from instance methods (which makes perfect sense when you know how Ruby works, but still came to me as a surprise). I didn't want to implement this method as a private instance method since it has nothing to do with the object state, but maybe I should in this situation? I read in Practical OO Design by Sandi Metz about a convention to leave all methods public and single out those that are not part of the public interface by prefixing their names with "_", but I'm not sure if I should start using that convention, it doesn't seem popular.

BTW. I'm not exactly sure if the optional "+1" should be inside ((+1 555) 555 5555) or outside (+1 (555) 555 5555) the optional parentheses.

Avatar of barberj

i like your use of class methods. i had a similar approach, but without class methods.

What can you learn from this solution?

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