resistor-color-duo

elixir/resistor-color-duo/.exercism/config.json

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+{
+  "authors": [
+    "jiegillet"
+  ],
+  "files": {
+    "solution": [
+      "lib/resistor_color_duo.ex"
+    ],
+    "test": [
+      "test/resistor_color_duo_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "blurb": "Convert color codes, as used on resistors, to a numeric value.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1464"
+}

elixir/resistor-color-duo/.exercism/metadata.json

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+{"track":"elixir","exercise":"resistor-color-duo","id":"e609b31ae73f414fac5537059d7440c0","url":"https://exercism.org/tracks/elixir/exercises/resistor-color-duo","handle":"negrienko","is_requester":true,"auto_approve":false}

elixir/resistor-color-duo/.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

elixir/resistor-color-duo/.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+resistor_color_duo-*.tar
+

elixir/resistor-color-duo/HELP.md

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+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bash
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be 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:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/resistor_color_duo.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- The [Elixir track's programming category on the forum](https://forum.exercism.org/c/programming/elixir)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.

elixir/resistor-color-duo/README.md

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+# Resistor Color Duo
+
+Welcome to Resistor Color Duo on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
+For this exercise, you need to know two things about them:
+
+- Each resistor has a resistance value.
+- Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.
+
+To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values.
+Each band has a position and a numeric value.
+
+The first 2 bands of a resistor have a simple encoding scheme: each color maps to a single number.
+For example, if they printed a brown band (value 1) followed by a green band (value 5), it would translate to the number 15.
+
+In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands.
+The program will take color names as input and output a two digit number, even if the input is more than two colors!
+
+The band colors are encoded as follows:
+
+- Black: 0
+- Brown: 1
+- Red: 2
+- Orange: 3
+- Yellow: 4
+- Green: 5
+- Blue: 6
+- Violet: 7
+- Grey: 8
+- White: 9
+
+From the example above:
+brown-green should return 15
+brown-green-violet should return 15 too, ignoring the third color.
+
+## Source
+
+### Created by
+
+- @jiegillet
+
+### Based on
+
+Maud de Vries, Erik Schierboom - https://github.com/exercism/problem-specifications/issues/1464

elixir/resistor-color-duo/lib/resistor_color_duo.ex

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+defmodule ResistorColorDuo do
+  @doc """
+  Calculate a resistance value from two colors
+  """
+  @spec value(colors :: [atom]) :: integer
+  def value(colors) do
+    colors
+    |> Enum.take(2)
+    |> Enum.map(&code/1)
+    |> Integer.undigits()
+  end
+
+
+  @spec code(atom) :: integer()
+  defp code(:black), do: 0
+  defp code(:brown), do: 1
+  defp code(:red), do: 2
+  defp code(:orange), do: 3
+  defp code(:yellow), do: 4
+  defp code(:green), do: 5
+  defp code(:blue), do: 6
+  defp code(:violet), do: 7
+  defp code(:grey), do: 8
+  defp code(:white), do: 9
+end

elixir/resistor-color-duo/mix.exs

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+defmodule ResistorColorDuo.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :resistor_color_duo,
+      version: "0.1.0",
+      # elixir: "~> 1.8",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end

elixir/resistor-color-duo/test/resistor_color_duo_test.exs

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+defmodule ResistorColorDuoTest do
+  use ExUnit.Case
+
+  test "Brown and black" do
+    colors = [:brown, :black]
+    output = ResistorColorDuo.value(colors)
+    expected = 10
+
+    assert output == expected
+  end
+
+  test "Blue and grey" do
+    colors = [:blue, :grey]
+    output = ResistorColorDuo.value(colors)
+    expected = 68
+
+    assert output == expected
+  end
+
+  test "Yellow and violet" do
+    colors = [:yellow, :violet]
+    output = ResistorColorDuo.value(colors)
+    expected = 47
+
+    assert output == expected
+  end
+
+  test "White and red" do
+    colors = [:white, :red]
+    output = ResistorColorDuo.value(colors)
+    expected = 92
+
+    assert output == expected
+  end
+
+  test "Orange and orange" do
+    colors = [:orange, :orange]
+    output = ResistorColorDuo.value(colors)
+    expected = 33
+
+    assert output == expected
+  end
+
+  test "Ignore additional colors" do
+    colors = [:green, :brown, :orange]
+    output = ResistorColorDuo.value(colors)
+    expected = 51
+
+    assert output == expected
+  end
+
+  test "Black and brown, one digit" do
+    colors = [:black, :brown]
+    output = ResistorColorDuo.value(colors)
+    expected = 1
+
+    assert output == expected
+  end
+end

elixir/resistor-color-duo/test/test_helper.exs

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