Add resistor-color-trio exercise (#53)

* Add resistor-color-trio exercise

* Fix spacing

Fix spacing so methods are 2 empty lines apart.

* Update space

* Update example.gd

Fix another spacing issue

Author: glaxxie

config.json

@@ -51,6 +51,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "resistor-color-trio",
+        "name": "Resistor Color Trio",
+        "uuid": "bf63aff6-54bf-484a-b00d-9a038db249aa",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "uuid": "c3b37c54-cc4e-49a5-a869-cd7700b0e448",
         "slug": "leap",

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

@@ -0,0 +1,56 @@
+# Instructions
+
+If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
+For this exercise, you need to know only three 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 acts as a digit of a 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 3 colors as input, and outputs the correct value, in ohms.
+  The color bands are encoded as follows:
+
+- Black: 0
+- Brown: 1
+- Red: 2
+- Orange: 3
+- Yellow: 4
+- Green: 5
+- Blue: 6
+- Violet: 7
+- Grey: 8
+- White: 9
+
+In Resistor Color Duo you decoded the first two colors.
+For instance: orange-orange got the main value `33`.
+The third color stands for how many zeros need to be added to the main value.
+The main value plus the zeros gives us a value in ohms.
+For the exercise it doesn't matter what ohms really are.
+For example:
+
+- orange-orange-black would be 33 and no zeros, which becomes 33 ohms.
+- orange-orange-red would be 33 and 2 zeros, which becomes 3300 ohms.
+- orange-orange-orange would be 33 and 3 zeros, which becomes 33000 ohms.
+
+(If Math is your thing, you may want to think of the zeros as exponents of 10.
+If Math is not your thing, go with the zeros.
+It really is the same thing, just in plain English instead of Math lingo.)
+
+This exercise is about translating the colors into a label:
+
+> "... ohms"
+
+So an input of `"orange", "orange", "black"` should return:
+
+> "33 ohms"
+
+When we get to larger resistors, a [metric prefix][metric-prefix] is used to indicate a larger magnitude of ohms, such as "kiloohms".
+That is similar to saying "2 kilometers" instead of "2000 meters", or "2 kilograms" for "2000 grams".
+
+For example, an input of `"orange", "orange", "orange"` should return:
+
+> "33 kiloohms"
+
+[metric-prefix]: https://en.wikipedia.org/wiki/Metric_prefix

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "glaxxie"
+  ],
+  "files": {
+    "solution": [
+      "resistor_color_trio.gd"
+    ],
+    "test": [
+      "resistor_color_trio_test.gd"
+    ],
+    "example": [
+      ".meta/example.gd"
+    ]
+  },
+  "blurb": "Convert color codes, as used on resistors, to a human-readable label.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1549"
+}

exercises/practice/resistor-color-trio/.meta/example.gd

@@ -0,0 +1,18 @@
+func color_code(colors):
+	var colors_code = ["black", "brown", "red", "orange", "yellow", "green", "blue", "violet", "grey", "white"]
+
+	var units = {
+		1e9: "gigaohms",
+		1e6: "megaohms",
+		1e3: "kiloohms"
+		}
+
+	var base_value = colors_code.find(colors[0]) * 10 + colors_code.find(colors[1])
+	var magnitude = 10 ** colors_code.find(colors[2])
+	var total = base_value * magnitude
+
+	for key in units.keys():
+		if total >= key:
+			return str(total / key) + " " + units[key]
+
+	return str(total) + " ohms"

exercises/practice/resistor-color-trio/resistor_color_trio.gd

@@ -0,0 +1,2 @@
+func color_code(colors):
+	pass

exercises/practice/resistor-color-trio/resistor_color_trio_test.gd

@@ -0,0 +1,59 @@
+func test_orange_and_orange_and_black(solution_script):
+	var colors   = ["orange", "orange", "black"]
+	var expected = "33 ohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_blue_and_grey_and_brown(solution_script):
+	var colors   = ["blue", "grey", "brown"]
+	var expected = "680 ohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_red_and_black_and_red(solution_script):
+	var colors   = ["red", "black", "red"]
+	var expected = "2 kiloohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_green_and_brown_and_orange(solution_script):
+	var colors   = ["green", "brown", "orange"]
+	var expected = "51 kiloohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_yellow_and_violet_and_yellow(solution_script):
+	var colors   = ["yellow", "violet", "yellow"]
+	var expected = "470 kiloohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_blue_and_violet_and_blue(solution_script):
+	var colors   = ["blue", "violet", "blue"]
+	var expected = "67 megaohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_minimum_possible_value(solution_script):
+	var colors   = ["black", "black", "black"]
+	var expected = "0 ohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_maximum_possible_value(solution_script):
+	var colors   = ["white", "white", "white"]
+	var expected = "99 gigaohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_first_two_colors_make_an_invalid_octal_number(solution_script):
+	var colors   = ["black", "grey", "black"]
+	var expected = "8 ohms"
+	return [expected, solution_script.color_code(colors)]
+
+
+func test_ignore_extra_colors(solution_script):
+	var colors   = ["blue", "green", "yellow", "orange"]
+	var expected = "650 kiloohms"
+	return [expected, solution_script.color_code(colors)]
+