Add resistor-color exercise (#363)

config.json

@@ -737,6 +737,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "resistor-color",
+        "name": "Resistor Color",
+        "uuid": "8af70f6c-85e2-41de-b5a3-20aaacb32a26",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1
+      },
       {
         "slug": "simple-cipher",
         "name": "Simple Cipher",

exercises/practice/resistor-color/.docs/instructions.md

@@ -0,0 +1,39 @@
+# 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.
+
+In this exercise you are going to create a helpful program so that you don't have to remember the values of the bands.
+
+These 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
+
+The goal of this exercise is to create a way:
+
+- to look up the numerical value associated with a particular color band
+- to list the different band colors
+
+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][e-color-code].
+
+[e-color-code]: https://en.wikipedia.org/wiki/Electronic_color_code

exercises/practice/resistor-color/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "erikschierboom"
+  ],
+  "files": {
+    "solution": [
+      "resistor-color.R"
+    ],
+    "test": [
+      "test_resistor-color.R"
+    ],
+    "example": [
+      ".meta/example.R"
+    ]
+  },
+  "blurb": "Convert a resistor band's color to its numeric representation.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1458"
+}

exercises/practice/resistor-color/.meta/example.R

@@ -0,0 +1,5 @@
+colors <- c("black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white") # nolint
+
+color_code <- function(color) {
+  match(color, colors) - 1
+}

exercises/practice/resistor-color/.meta/tests.toml

@@ -0,0 +1,22 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[49eb31c5-10a8-4180-9f7f-fea632ab87ef]
+description = "Color codes -> Black"
+
+[0a4df94b-92da-4579-a907-65040ce0b3fc]
+description = "Color codes -> White"
+
+[5f81608d-f36f-4190-8084-f45116b6f380]
+description = "Color codes -> Orange"
+
+[581d68fa-f968-4be2-9f9d-880f2fb73cf7]
+description = "Colors"

exercises/practice/resistor-color/resistor-color.R

@@ -0,0 +1,5 @@
+# TODO: define `colors` variable
+
+color_code <- function(color) {
+
+}

exercises/practice/resistor-color/test_resistor-color.R

@@ -0,0 +1,19 @@
+source("./resistor-color.R")
+library(testthat)
+
+test_that("Colors", {
+  expected <- c("black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white") # nolint
+  expect_equal(colors, expected)
+})
+
+test_that("Black", {
+  expect_equal(color_code("black"), 0)
+})
+
+test_that("White", {
+  expect_equal(color_code("white"), 9)
+})
+
+test_that("Orange", {
+  expect_equal(color_code("orange"), 3)
+})