resistor-colors: Implement exercise

config.json

@@ -1554,6 +1554,16 @@
       "topics": [
         "arrays"
       ]
+    },
+    {
+      "slug": "resistor-colors",
+      "uuid": "089f06a6-0759-479c-8c00-d699525a1e22",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "arrays"
+      ]
     }
   ]
 }

exercises/resistor-colors/README.md

@@ -0,0 +1,72 @@
+# Resistor Colors
+
+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 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 two colors as input, and output the correct number.
+
+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
+
+
+## Exception messages
+
+Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
+indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
+every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
+a message.
+
+To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
+`raise Exception`, you should write:
+
+```python
+raise Exception("Meaningful message indicating the source of the error")
+```
+
+## Running the tests
+
+To run the tests, run the appropriate command below ([why they are different](https://github.com/pytest-dev/pytest/issues/1629#issue-161422224)):
+
+- Python 2.7: `py.test resistor_colors_test.py`
+- Python 3.4+: `pytest resistor_colors_test.py`
+
+Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
+`python -m pytest resistor_colors_test.py`
+
+### Common `pytest` options
+
+- `-v` : enable verbose output
+- `-x` : stop running tests on first failure
+- `--ff` : run failures from previous test before running other test cases
+
+For other options, see `python -m pytest -h`
+
+## Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/resistor-colors` directory.
+
+You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.
+
+For more detailed information about running tests, code style and linting,
+please see [Running the Tests](http://exercism.io/tracks/python/tests).
+
+## Source
+
+Maud de Vries, Erik Schierboom [https://github.com/exercism/problem-specifications/issues/1464](https://github.com/exercism/problem-specifications/issues/1464)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/resistor-colors/example.py

@@ -0,0 +1,16 @@
+COLORS = [
+    'black',
+    'brown',
+    'red',
+    'orange',
+    'yellow',
+    'green',
+    'blue',
+    'violet',
+    'grey',
+    'white'
+]
+
+
+def value(colors):
+    return 10 * COLORS.index(colors[0]) + COLORS.index(colors[1])

exercises/resistor-colors/resistor_colors.py

@@ -0,0 +1,2 @@
+def value(colors):
+    pass

exercises/resistor-colors/resistor_colors_test.py

@@ -0,0 +1,23 @@
+import unittest
+
+from resistor_colors import value
+
+
+# Tests adapted from `problem-specifications//canonical-data.json` @ v1.0.0
+
+class ResistorColorsTest(unittest.TestCase):
+    def test_brown_and_black(self):
+        self.assertEqual(value(['brown', 'black']), 10)
+
+    def test_blue_and_grey(self):
+        self.assertEqual(value(['blue', 'grey']), 68)
+
+    def test_yellow_and_violet(self):
+        self.assertEqual(value(['yellow', 'violet']), 47)
+
+    def test_orange_and_orange(self):
+        self.assertEqual(value(['orange', 'orange']), 33)
+
+
+if __name__ == '__main__':
+    unittest.main()