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to Twelve Days in the Python Track

Published at Jul 25 2019 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

Output the lyrics to 'The Twelve Days of Christmas'.

On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.

On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.

On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.

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:

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):

  • Python 2.7: py.test twelve_days_test.py
  • Python 3.4+: pytest twelve_days_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 twelve_days_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/twelve-days 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.

Source

Wikipedia http://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song)

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

twelve_days_test.py

import unittest

from twelve_days import recite


# Tests adapted from `problem-specifications//canonical-data.json` @ v1.2.0

class TwelveDaysTest(unittest.TestCase):
    def test_verse1(self):
        expected = ["On the first day of Christmas my true love gave to me: "
                    "a Partridge in a Pear Tree."]
        self.assertEqual(recite(1, 1), expected)

    def test_verse2(self):
        expected = ["On the second day of Christmas my true love gave to me: "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(2, 2), expected)

    def test_verse3(self):
        expected = ["On the third day of Christmas my true love gave to me: "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(3, 3), expected)

    def test_verse4(self):
        expected = ["On the fourth day of Christmas my true love gave to me: "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(4, 4), expected)

    def test_verse5(self):
        expected = ["On the fifth day of Christmas my true love gave to me: "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(5, 5), expected)

    def test_verse6(self):
        expected = ["On the sixth day of Christmas my true love gave to me: "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(6, 6), expected)

    def test_verse7(self):
        expected = ["On the seventh day of Christmas my true love gave to me: "
                    "seven Swans-a-Swimming, "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(7, 7), expected)

    def test_verse8(self):
        expected = ["On the eighth day of Christmas my true love gave to me: "
                    "eight Maids-a-Milking, "
                    "seven Swans-a-Swimming, "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(8, 8), expected)

    def test_verse9(self):
        expected = ["On the ninth day of Christmas my true love gave to me: "
                    "nine Ladies Dancing, "
                    "eight Maids-a-Milking, "
                    "seven Swans-a-Swimming, "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(9, 9), expected)

    def test_verse10(self):
        expected = ["On the tenth day of Christmas my true love gave to me: "
                    "ten Lords-a-Leaping, "
                    "nine Ladies Dancing, "
                    "eight Maids-a-Milking, "
                    "seven Swans-a-Swimming, "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(10, 10), expected)

    def test_verse11(self):
        expected = ["On the eleventh day of Christmas "
                    "my true love gave to me: "
                    "eleven Pipers Piping, "
                    "ten Lords-a-Leaping, "
                    "nine Ladies Dancing, "
                    "eight Maids-a-Milking, "
                    "seven Swans-a-Swimming, "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(11, 11), expected)

    def test_verse12(self):
        expected = ["On the twelfth day of Christmas my true love gave to me: "
                    "twelve Drummers Drumming, "
                    "eleven Pipers Piping, "
                    "ten Lords-a-Leaping, "
                    "nine Ladies Dancing, "
                    "eight Maids-a-Milking, "
                    "seven Swans-a-Swimming, "
                    "six Geese-a-Laying, "
                    "five Gold Rings, "
                    "four Calling Birds, "
                    "three French Hens, "
                    "two Turtle Doves, "
                    "and a Partridge in a Pear Tree."]
        self.assertEqual(recite(12, 12), expected)

    def test_first_three_verses_of_the_song(self):
        expected = [recite(n, n)[0] for n in range(1, 4)]
        self.assertEqual(recite(1, 3), expected)

    def test_three_verses_from_the_middle_of_the_song(self):
        expected = [recite(n, n)[0] for n in range(4, 7)]
        self.assertEqual(recite(4, 6), expected)

    def test_the_whole_song(self):
        expected = [recite(n, n)[0] for n in range(1, 13)]
        self.assertEqual(recite(1, 12), expected)


if __name__ == '__main__':
    unittest.main()
BASE = "On the {} day of Christmas my true love gave to me: "

DAY_NAMES = [
    "first",
    "second",
    "third",
    "fourth",
    "fifth",
    "sixth",
    "seventh",
    "eighth",
    "ninth",
    "tenth",
    "eleventh",
    "twelfth"
]

VERSES = [
    "a Partridge in a Pear Tree.",
    "two Turtle Doves",
    "three French Hens",
    "four Calling Birds",
    "five Gold Rings",
    "six Geese-a-Laying",
    "seven Swans-a-Swimming",
    "eight Maids-a-Milking",
    "nine Ladies Dancing",
    "ten Lords-a-Leaping",
    "eleven Pipers Piping",
    "twelve Drummers Drumming"
]

def recite(start_verse, end_verse):
    if not isinstance(start_verse, int): raise ValueError
    if not isinstance(end_verse, int): raise ValueError
    return [verse(n) for n in range(start_verse - 1, end_verse)]

def verse(n):
    middle = ", ".join(VERSES[n:0:-1]) + ", and " if n > 0 else ""
    return BASE.format(DAY_NAMES[n]) + middle + VERSES[0]

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