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to Twelve Days in the Java Track

Published at Jul 13 2018 · 0 comments
Instructions
Test suite
Solution

Note:

This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code 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.

Running the tests

You can run all the tests for an exercise by entering

$ gradle test

in your terminal.

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.

TwelveDaysTest.java

import org.junit.Before;
import org.junit.Ignore;
import org.junit.Test;

import static org.junit.Assert.assertEquals;

public class TwelveDaysTest {
    private TwelveDays twelveDays;

    @Before
    public void setup() {
        twelveDays = new TwelveDays();
    }

    @Test
    public void testVerseOne() {
        String expectedVerseOne = "On the first day of Christmas my true love gave to me, " +
                "a Partridge in a Pear Tree.\n";
        assertEquals(expectedVerseOne, twelveDays.verse(1));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseTwo() {
        String expectedVerseTwo = "On the second day of Christmas my true love gave to me, two Turtle Doves, " +
                "and a Partridge in a Pear Tree.\n";
        assertEquals(expectedVerseTwo, twelveDays.verse(2));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseThree() {
        String expectedVerseThree = "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.\n";
        assertEquals(expectedVerseThree, twelveDays.verse(3));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseFour() {
        String expectedVerseFour = "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.\n";
        assertEquals(expectedVerseFour, twelveDays.verse(4));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseFive() {
        String expectedVerseFive = "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.\n";
        assertEquals(expectedVerseFive, twelveDays.verse(5));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseSix() {
        String expectedVerseSix = "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.\n";
        assertEquals(expectedVerseSix, twelveDays.verse(6));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseSeven() {
        String expectedVerseSeven = "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.\n";
        assertEquals(expectedVerseSeven, twelveDays.verse(7));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseEight() {
        String expectedVerseEight = "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.\n";
        assertEquals(expectedVerseEight, twelveDays.verse(8));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseNine() {
        String expectedVerseNine = "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.\n";
        assertEquals(expectedVerseNine, twelveDays.verse(9));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseTen() {
        String expectedVerseTen = "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.\n";
        assertEquals(expectedVerseTen, twelveDays.verse(10));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseEleven() {
        String expectedVerseEleven = "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.\n";
        assertEquals(expectedVerseEleven, twelveDays.verse(11));
    }

    @Ignore("Remove to run test")
    @Test
    public void testVerseTwelve() {
        String expectedVerseTwelve = "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.\n";
        assertEquals(expectedVerseTwelve, twelveDays.verse(12));
    }

    @Ignore("Remove to run test")
    @Test
    public void testFirstThreeVerses() {
        String expectedVersesOneToThree = "On the first day of Christmas my true love gave to me, " +
                "a Partridge in a Pear Tree.\n\n" +
                "On the second day of Christmas my true love gave to me, two Turtle Doves, " +
                "and a Partridge in a Pear Tree.\n\n" +
                "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.\n";
        assertEquals(expectedVersesOneToThree, twelveDays.verses(1, 3));
    }

    @Ignore("Remove to run test")
    @Test
    public void testFourthToSixthVerses() {
        String expectedVersesFourToSix = "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.\n\n" +
                "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.\n\n" +
                "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.\n";
        assertEquals(expectedVersesFourToSix, twelveDays.verses(4, 6));
    }

    @Ignore("Remove to run test")
    @Test
    public void testSingWholeSong() {
        String expectedSong = "On the first day of Christmas my true love gave to me, a Partridge in a Pear Tree.\n" +
                "\n" +
                "On the second day of Christmas my true love gave to me, two Turtle Doves, " +
                "and a Partridge in a Pear Tree.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n" +
                "\n" +
                "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.\n";
        assertEquals(expectedSong, twelveDays.sing());
    }
}
import java.util.HashMap;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

class Verse {

  private static final Map<Integer, String> NUMBER_TO_ORDINAL = numberToOrdinal();
  private static final Map<Integer, String> NUMBER_TO_GIFT = numberToGift();

  static String toString(int verseIndex) {
    return prefix(verseIndex) + body(verseIndex) + suffix(verseIndex);
  }

  private static String prefix(int verseIndex) {
    return String.format("On the %s day of Christmas my true love gave to me, ", ordinal(verseIndex));
  }

  private static String body(int verseIndex) {
    return revRangeClosed(1, verseIndex)
            .mapToObj(Verse::gifts)
            .collect(Collectors.joining(", "));
  }

  private static String suffix(int verseIndex) {
    if (verseIndex > 1) {
      return ", and a Partridge in a Pear Tree.\n";
    }
    return "a Partridge in a Pear Tree.\n";
  }

  private static String ordinal(int number) {
    return NUMBER_TO_ORDINAL.get(number);
  }

  private static String gifts(int giftIndex) {
    return NUMBER_TO_GIFT.get(giftIndex);
  }

  private static Map<Integer, String> numberToGift() {
    Map<Integer, String> numberToGift = new HashMap<>();
    numberToGift.put(2, "two Turtle Doves");
    numberToGift.put(3, "three French Hens");
    numberToGift.put(4, "four Calling Birds");
    numberToGift.put(5, "five Gold Rings");
    numberToGift.put(6, "six Geese-a-Laying");
    numberToGift.put(7, "seven Swans-a-Swimming");
    numberToGift.put(8, "eight Maids-a-Milking");
    numberToGift.put(9, "nine Ladies Dancing");
    numberToGift.put(10, "ten Lords-a-Leaping");
    numberToGift.put(11, "eleven Pipers Piping");
    numberToGift.put(12, "twelve Drummers Drumming");
    return numberToGift;
  }

  private static Map<Integer, String> numberToOrdinal() {
    Map<Integer, String> numberToOrdinal = new HashMap<>();
    numberToOrdinal.put(1, "first");
    numberToOrdinal.put(2, "second");
    numberToOrdinal.put(3, "third");
    numberToOrdinal.put(4, "fourth");
    numberToOrdinal.put(5, "fifth");
    numberToOrdinal.put(6, "sixth");
    numberToOrdinal.put(7, "seventh");
    numberToOrdinal.put(8, "eighth");
    numberToOrdinal.put(9, "ninth");
    numberToOrdinal.put(10, "tenth");
    numberToOrdinal.put(11, "eleventh");
    numberToOrdinal.put(12, "twelfth");
    return numberToOrdinal;
  }

  private static IntStream revRangeClosed(int from, int to) {
    return IntStream.range(from, to)
            .map(i -> to - i + from);
  }

}

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