Add resistor-color-duo exercise

config.json

@@ -153,6 +153,14 @@
           "math"
         ]
       },
+      {
+        "slug": "resistor-color-duo",
+        "name": "Resistor Color Duo",
+        "uuid": "f8f53f73-05dd-4732-994f-77eeaea6aa41",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "rna-transcription",
         "name": "Rna Transcription",

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

@@ -0,0 +1,33 @@
+# 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.

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "resistor-color-duo.coffee"
+    ],
+    "test": [
+      "resistor-color-duo.spec.coffee"
+    ],
+    "example": [
+      ".meta/example.coffee"
+    ]
+  },
+  "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"
+}

exercises/practice/resistor-color-duo/.meta/example.coffee

@@ -0,0 +1,18 @@
+class ResistorColorDuo
+  colorBands: [
+        "black"
+        "brown"
+        "red"
+        "orange"
+        "yellow"
+        "green"
+        "blue"
+        "violet"
+        "grey"
+        "white"
+    ]
+
+  value: ([first, second]) ->
+   10 * @colorBands.indexOf(first) + @colorBands.indexOf(second)
+
+module.exports = ResistorColorDuo

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

@@ -0,0 +1,31 @@
+# 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.
+
+[ce11995a-5b93-4950-a5e9-93423693b2fc]
+description = "Brown and black"
+
+[7bf82f7a-af23-48ba-a97d-38d59406a920]
+description = "Blue and grey"
+
+[f1886361-fdfd-4693-acf8-46726fe24e0c]
+description = "Yellow and violet"
+
+[b7a6cbd2-ae3c-470a-93eb-56670b305640]
+description = "White and red"
+
+[77a8293d-2a83-4016-b1af-991acc12b9fe]
+description = "Orange and orange"
+
+[0c4fb44f-db7c-4d03-afa8-054350f156a8]
+description = "Ignore additional colors"
+
+[4a8ceec5-0ab4-4904-88a4-daf953a5e818]
+description = "Black and brown, one-digit"

exercises/practice/resistor-color-duo/resistor-color-duo.coffee

@@ -0,0 +1,5 @@
+class ResistorColorDuo
+
+  value: (colors) ->
+
+module.exports = ResistorColorDuo

exercises/practice/resistor-color-duo/resistor-color-duo.spec.coffee

@@ -0,0 +1,38 @@
+ResistorColorDuo = require './resistor-color-duo'
+
+describe 'ResistorColorDuo', ->
+  rc = new ResistorColorDuo()
+  it 'Brown and black', ->
+    results = rc.value(['brown', 'black'])
+    expected = 10
+    expect(results).toEqual expected
+
+  it 'Blue and grey', ->
+    results = rc.value(['blue', 'grey'])
+    expected = 68
+    expect(results).toEqual expected
+
+  it 'Yellow and violet', ->
+    results = rc.value(['yellow', 'violet'])
+    expected = 47
+    expect(results).toEqual expected
+
+  it 'White and red', ->
+    results = rc.value(['white', 'red'])
+    expected = 92
+    expect(results).toEqual expected
+
+  it 'Orange and orange', ->
+    results = rc.value(['orange', 'orange'])
+    expected = 33
+    expect(results).toEqual expected
+
+  it 'Ignore additional colors', ->
+    results = rc.value(['green', 'brown', 'orange'])
+    expected = 51
+    expect(results).toEqual expected
+
+  it 'Black and brown, one-digit', ->
+    results = rc.value(['black', 'brown'])
+    expected = 1
+    expect(results).toEqual expected