Resistors have color coded bands, where each color maps to a number. The first 2 bands of a resistor have a simple encoding scheme: each color maps to a single number.
These colors are encoded as follows:
Mnemonics map the colors to the numbers, that, when stored as an array, happen to map to their index in the array: Better Be Right Or Your Great Big Values Go Wrong.
More information on the color encoding of resistors can be found in the Electronic color code Wikipedia article
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:
To include color from the command line:
ruby -r minitest/pride resistor_color_test.rb
Maud de Vries, Erik Schierboom https://github.com/exercism/problem-specifications/issues/1458
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
require 'minitest/autorun' require_relative 'resistor_color' # Common test data version: 1.0.0 edf1778 class ResistorColorTest < Minitest::Test def test_black # skip assert_equal 0, ResistorColor.color_code("black") end def test_white skip assert_equal 9, ResistorColor.color_code("white") end def test_orange skip assert_equal 3, ResistorColor.color_code("orange") end def test_colors skip expected = ["black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white"] assert_equal expected, ResistorColor::COLORS end end
class ResistorColor COLORS = %w[black brown red orange yellow green blue violet grey white].freeze def self.color_code(color) COLORS.index(color.downcase) end end
A huge amount can be learned 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.