Sync scale-generator with problem-specifications

This brought in a slew of changes that required updating
the sample solution.

The TL;DR is that the last character pattern passed to the interval
was being ignored before, when it should not be.

Author: kytrinyx

exercises/practice/scale-generator/.docs/instructions.md

@@ -1,49 +1,68 @@
 # Instructions
 
-Given a tonic, or starting note, and a set of intervals, generate
-the musical scale starting with the tonic and following the
-specified interval pattern.
+## Chromatic Scales
 
-Scales in Western music are based on the chromatic (12-note) scale. This
-scale can be expressed as the following group of pitches:
+Scales in Western music are based on the chromatic (12-note) scale.
+This scale can be expressed as the following group of pitches:
 
-A, A#, B, C, C#, D, D#, E, F, F#, G, G#
+> A, A♯, B, C, C♯, D, D♯, E, F, F♯, G, G♯
 
-A given sharp note (indicated by a #) can also be expressed as the flat
-of the note above it (indicated by a b) so the chromatic scale can also be
-written like this:
+A given sharp note (indicated by a ♯) can also be expressed as the flat of the note above it (indicated by a ♭) so the chromatic scale can also be written like this:
 
-A, Bb, B, C, Db, D, Eb, E, F, Gb, G, Ab
+> A, B♭, B, C, D♭, D, E♭, E, F, G♭, G, A♭
 
-The major and minor scale and modes are subsets of this twelve-pitch
-collection. They have seven pitches, and are called diatonic scales.
-The collection of notes in these scales is written with either sharps or
-flats, depending on the tonic. Here is a list of which are which:
+The major and minor scale and modes are subsets of this twelve-pitch collection.
+They have seven pitches, and are called diatonic scales.
+The collection of notes in these scales is written with either sharps or flats, depending on the tonic (starting note).
+Here is a table indicating whether the flat expression or sharp expression of the scale would be used for a given tonic:
 
-No Sharps or Flats:
-C major
-a minor
+| Key Signature | Major                 | Minor                |
+| ------------- | --------------------- | -------------------- |
+| Natural       | C                     | a                    |
+| Sharp         | G, D, A, E, B, F♯     | e, b, f♯, c♯, g♯, d♯ |
+| Flat          | F, B♭, E♭, A♭, D♭, G♭ | d, g, c, f, b♭, e♭   |
 
-Use Sharps:
-G, D, A, E, B, F# major
-e, b, f#, c#, g#, d# minor
+Note that by common music theory convention the natural notes "C" and "a" follow the sharps scale when ascending and the flats scale when descending.
+For the scope of this exercise the scale is only ascending.
 
-Use Flats:
-F, Bb, Eb, Ab, Db, Gb major
-d, g, c, f, bb, eb minor
+### Task
 
-The diatonic scales, and all other scales that derive from the
-chromatic scale, are built upon intervals. An interval is the space
-between two pitches.
+Given a tonic, generate the 12 note chromatic scale starting with the tonic.
 
-The simplest interval is between two adjacent notes, and is called a
-"half step", or "minor second" (sometimes written as a lower-case "m").
-The interval between two notes that have an interceding note is called
-a "whole step" or "major second" (written as an upper-case "M"). The
-diatonic scales are built using only these two intervals between
-adjacent notes.
+- Shift the base scale appropriately so that all 12 notes are returned starting with the given tonic.
+- For the given tonic, determine if the scale is to be returned with flats or sharps.
+- Return all notes in uppercase letters (except for the `b` for flats) irrespective of the casing of the given tonic.
 
-Non-diatonic scales can contain other intervals.  An "augmented second"
-interval, written "A", has two interceding notes (e.g., from A to C or Db to E)
-or a "whole step" plus a "half step". There are also smaller and larger
-intervals, but they will not figure into this exercise.
+## Diatonic Scales
+
+The diatonic scales, and all other scales that derive from the chromatic scale, are built upon intervals.
+An interval is the space between two pitches.
+
+The simplest interval is between two adjacent notes, and is called a "half step", or "minor second" (sometimes written as a lower-case "m").
+The interval between two notes that have an interceding note is called a "whole step" or "major second" (written as an upper-case "M").
+The diatonic scales are built using only these two intervals between adjacent notes.
+
+Non-diatonic scales can contain other intervals.
+An "augmented second" interval, written "A", has two interceding notes (e.g., from A to C or D♭ to E) or a "whole step" plus a "half step".
+There are also smaller and larger intervals, but they will not figure into this exercise.
+
+### Task
+
+Given a tonic and a set of intervals, generate the musical scale starting with the tonic and following the specified interval pattern.
+
+This is similar to generating chromatic scales except that instead of returning 12 notes, you will return N+1 notes for N intervals.
+The first note is always the given tonic.
+Then, for each interval in the pattern, the next note is determined by starting from the previous note and skipping the number of notes indicated by the interval.
+
+For example, starting with G and using the seven intervals MMmMMMm, there would be the following eight notes:
+
+Note | Reason
+--|--
+G | Tonic
+A | M indicates a whole step from G, skipping G♯
+B | M indicates a whole step from A, skipping A♯
+C | m indicates a half step from B, skipping nothing
+D | M indicates a whole step from C, skipping C♯
+E | M indicates a whole step from D, skipping D♯
+F♯ | M indicates a whole step from E, skipping F
+G | m indicates a half step from F♯, skipping nothing

exercises/practice/scale-generator/.meta/config.json

@@ -1,5 +1,5 @@
 {
-  "blurb": "Generate musical scales, given a starting note and a set of intervals. ",
+  "blurb": "Generate musical scales, given a starting note and a set of intervals.",
   "authors": [
     "fluxusfrequency"
   ],

exercises/practice/scale-generator/.meta/example.rb

@@ -14,10 +14,10 @@ def chromatic
   end
 
   def interval(pattern)
-    last_index = 0
-    scale = pattern.each_char.with_object([]) do |c, collector|
-      collector << reorder_chromatic_scale[last_index]
-      last_index += ASCENDING_INTERVALS.index(c) + 1
+    index = 0
+    pattern.each_char.with_object([reorder_chromatic_scale[index]]) do |char, scale|
+      index = (index + (ASCENDING_INTERVALS.index(char) + 1)) % 12
+      scale << reorder_chromatic_scale[index]
     end
   end
 

exercises/practice/scale-generator/.meta/tests.toml

@@ -10,52 +10,127 @@
 # is regenerated, comments can be added via a `comment` key.
 
 [10ea7b14-8a49-40be-ac55-7c62b55f9b47]
-description = "Chromatic scale with sharps"
+description = "Chromatic scales -> Chromatic scale with sharps"
 
 [af8381de-9a72-4efd-823a-48374dbfe76f]
-description = "Chromatic scale with flats"
+description = "Chromatic scales -> Chromatic scale with flats"
+
+[7195998a-7be7-40c9-8877-a1d7949e061b]
+description = "Scales with specified intervals -> Simple major scale"
+reimplements = "6f5b1410-1dd7-4c6c-b410-6b7e986f6f1e"
+
+[fe853b97-1878-4090-b218-4029246abb91]
+description = "Scales with specified intervals -> Major scale with sharps"
+reimplements = "13a92f89-a83e-40b5-b9d4-01136931ba02"
+
+[d60cb414-cc02-4fcb-ad7a-fc7ef0a9eead]
+description = "Scales with specified intervals -> Major scale with flats"
+reimplements = "aa3320f6-a761-49a1-bcf6-978e0c81080a"
+
+[77dab9b3-1bbc-4f9a-afd8-06da693bcc67]
+description = "Scales with specified intervals -> Minor scale with sharps"
+reimplements = "63daeb2f-c3f9-4c45-92be-5bf97f61ff94"
+
+[5fa1728f-5b66-4b43-9b7c-84359b7069d4]
+description = "Scales with specified intervals -> Minor scale with flats"
+reimplements = "616594d0-9c48-4301-949e-af1d4fad16fd"
+
+[f3f1c353-8f7b-4a85-a5b5-ae06c2645823]
+description = "Scales with specified intervals -> Dorian mode"
+reimplements = "390bd12c-5ac7-4ec7-bdde-4e58d5c78b0a"
+
+[5fe14e5a-3ddc-4202-a158-2c1158beb5d0]
+description = "Scales with specified intervals -> Mixolydian mode"
+reimplements = "846d0862-0f3e-4f3b-8a2d-9cc74f017848"
+
+[e6307799-b7f6-43fc-a6d8-a4834d6e2bdb]
+description = "Scales with specified intervals -> Lydian mode"
+reimplements = "7d49a8bb-b5f7-46ad-a207-83bd5032291a"
+
+[7c4a95cd-ecf4-448d-99bc-dbbca51856e0]
+description = "Scales with specified intervals -> Phrygian mode"
+reimplements = "a4e4dac5-1891-4160-a19f-bb06d653d4d0"
+
+[f476f9c9-5a13-473d-bb6c-f884cf8fd9f2]
+description = "Scales with specified intervals -> Locrian mode"
+reimplements = "ef3650af-90f8-4ad9-9ef6-fdbeae07dcaa"
+
+[87fdbcca-d3dd-46d5-9c56-ec79e25b19f4]
+description = "Scales with specified intervals -> Harmonic minor"
+reimplements = "70517400-12b7-4530-b861-fa940ae69ee8"
+
+[b28ecc18-88db-4fd5-a973-cfe6361e2b24]
+description = "Scales with specified intervals -> Octatonic"
+reimplements = "37114c0b-c54d-45da-9f4b-3848201470b0"
+
+[a1c7d333-6fb3-4f3b-9178-8a0cbe043134]
+description = "Scales with specified intervals -> Hexatonic"
+reimplements = "496466e7-aa45-4bbd-a64d-f41030feed9c"
+
+[9acfd139-0781-4926-8273-66a478c3b287]
+description = "Scales with specified intervals -> Pentatonic"
+reimplements = "bee5d9ec-e226-47b6-b62b-847a9241f3cc"
+
+[31c933ca-2251-4a5b-92dd-9d5831bc84ad]
+description = "Scales with specified intervals -> Enigmatic"
+reimplements = "dbee06a6-7535-4ab7-98e8-d8a36c8402d1"
 
 [6f5b1410-1dd7-4c6c-b410-6b7e986f6f1e]
-description = "Simple major scale"
+description = "Scales with specified intervals -> Simple major scale"
+include = false
 
 [13a92f89-a83e-40b5-b9d4-01136931ba02]
-description = "Major scale with sharps"
+description = "Scales with specified intervals -> Major scale with sharps"
+include = false
 
 [aa3320f6-a761-49a1-bcf6-978e0c81080a]
-description = "Major scale with flats"
+description = "Scales with specified intervals -> Major scale with flats"
+include = false
 
 [63daeb2f-c3f9-4c45-92be-5bf97f61ff94]
-description = "Minor scale with sharps"
+description = "Scales with specified intervals -> Minor scale with sharps"
+include = false
 
 [616594d0-9c48-4301-949e-af1d4fad16fd]
-description = "Minor scale with flats"
+description = "Scales with specified intervals -> Minor scale with flats"
+include = false
 
 [390bd12c-5ac7-4ec7-bdde-4e58d5c78b0a]
-description = "Dorian mode"
+description = "Scales with specified intervals -> Dorian mode"
+include = false
 
 [846d0862-0f3e-4f3b-8a2d-9cc74f017848]
-description = "Mixolydian mode"
+description = "Scales with specified intervals -> Mixolydian mode"
+include = false
 
 [7d49a8bb-b5f7-46ad-a207-83bd5032291a]
-description = "Lydian mode"
+description = "Scales with specified intervals -> Lydian mode"
+include = false
 
 [a4e4dac5-1891-4160-a19f-bb06d653d4d0]
-description = "Phrygian mode"
+description = "Scales with specified intervals -> Phrygian mode"
+include = false
 
 [ef3650af-90f8-4ad9-9ef6-fdbeae07dcaa]
-description = "Locrian mode"
+description = "Scales with specified intervals -> Locrian mode"
+include = false
 
 [70517400-12b7-4530-b861-fa940ae69ee8]
-description = "Harmonic minor"
+description = "Scales with specified intervals -> Harmonic minor"
+include = false
 
 [37114c0b-c54d-45da-9f4b-3848201470b0]
-description = "Octatonic"
+description = "Scales with specified intervals -> Octatonic"
+include = false
 
 [496466e7-aa45-4bbd-a64d-f41030feed9c]
-description = "Hexatonic"
+description = "Scales with specified intervals -> Hexatonic"
+include = false
 
 [bee5d9ec-e226-47b6-b62b-847a9241f3cc]
-description = "Pentatonic"
+description = "Scales with specified intervals -> Pentatonic"
+include = false
 
 [dbee06a6-7535-4ab7-98e8-d8a36c8402d1]
-description = "Enigmatic"
+description = "Scales with specified intervals -> Enigmatic"
+include = false

exercises/practice/scale-generator/scale_generator_test.rb

@@ -17,90 +17,90 @@ def test_chromatic_scales_chromatic_scale_with_flats
   def test_scales_with_specified_intervals_simple_major_scale
     skip
     scale = Scale.new("C")
-    assert_equal %w[C D E F G A B], scale.interval("MMmMMMm")
+    assert_equal %w[C D E F G A B C], scale.interval("MMmMMMm")
   end
 
   def test_scales_with_specified_intervals_major_scale_with_sharps
     skip
     scale = Scale.new("G")
-    assert_equal ["G", "A", "B", "C", "D", "E", "F#"], scale.interval("MMmMMMm")
+    assert_equal ["G", "A", "B", "C", "D", "E", "F#", "G"], scale.interval("MMmMMMm")
   end
 
   def test_scales_with_specified_intervals_major_scale_with_flats
     skip
     scale = Scale.new("F")
-    assert_equal %w[F G A Bb C D E], scale.interval("MMmMMMm")
+    assert_equal %w[F G A Bb C D E F], scale.interval("MMmMMMm")
   end
 
   def test_scales_with_specified_intervals_minor_scale_with_sharps
     skip
     scale = Scale.new("f#")
-    assert_equal ["F#", "G#", "A", "B", "C#", "D", "E"], scale.interval("MmMMmMM")
+    assert_equal ["F#", "G#", "A", "B", "C#", "D", "E", "F#"], scale.interval("MmMMmMM")
   end
 
   def test_scales_with_specified_intervals_minor_scale_with_flats
     skip
     scale = Scale.new("bb")
-    assert_equal %w[Bb C Db Eb F Gb Ab], scale.interval("MmMMmMM")
+    assert_equal %w[Bb C Db Eb F Gb Ab Bb], scale.interval("MmMMmMM")
   end
 
   def test_scales_with_specified_intervals_dorian_mode
     skip
     scale = Scale.new("d")
-    assert_equal %w[D E F G A B C], scale.interval("MmMMMmM")
+    assert_equal %w[D E F G A B C D], scale.interval("MmMMMmM")
   end
 
   def test_scales_with_specified_intervals_mixolydian_mode
     skip
     scale = Scale.new("Eb")
-    assert_equal %w[Eb F G Ab Bb C Db], scale.interval("MMmMMmM")
+    assert_equal %w[Eb F G Ab Bb C Db Eb], scale.interval("MMmMMmM")
   end
 
   def test_scales_with_specified_intervals_lydian_mode
     skip
     scale = Scale.new("a")
-    assert_equal ["A", "B", "C#", "D#", "E", "F#", "G#"], scale.interval("MMMmMMm")
+    assert_equal ["A", "B", "C#", "D#", "E", "F#", "G#", "A"], scale.interval("MMMmMMm")
   end
 
   def test_scales_with_specified_intervals_phrygian_mode
     skip
     scale = Scale.new("e")
-    assert_equal %w[E F G A B C D], scale.interval("mMMMmMM")
+    assert_equal %w[E F G A B C D E], scale.interval("mMMMmMM")
   end
 
   def test_scales_with_specified_intervals_locrian_mode
     skip
     scale = Scale.new("g")
-    assert_equal %w[G Ab Bb C Db Eb F], scale.interval("mMMmMMM")
+    assert_equal %w[G Ab Bb C Db Eb F G], scale.interval("mMMmMMM")
   end
 
   def test_scales_with_specified_intervals_harmonic_minor
     skip
     scale = Scale.new("d")
-    assert_equal %w[D E F G A Bb Db], scale.interval("MmMMmAm")
+    assert_equal %w[D E F G A Bb Db D], scale.interval("MmMMmAm")
   end
 
   def test_scales_with_specified_intervals_octatonic
     skip
     scale = Scale.new("C")
-    assert_equal ["C", "D", "D#", "F", "F#", "G#", "A", "B"], scale.interval("MmMmMmMm")
+    assert_equal ["C", "D", "D#", "F", "F#", "G#", "A", "B", "C"], scale.interval("MmMmMmMm")
   end
 
   def test_scales_with_specified_intervals_hexatonic
     skip
     scale = Scale.new("Db")
-    assert_equal %w[Db Eb F G A B], scale.interval("MMMMMM")
+    assert_equal %w[Db Eb F G A B Db], scale.interval("MMMMMM")
   end
 
   def test_scales_with_specified_intervals_pentatonic
     skip
     scale = Scale.new("A")
-    assert_equal ["A", "B", "C#", "E", "F#"], scale.interval("MMAMA")
+    assert_equal ["A", "B", "C#", "E", "F#", "A"], scale.interval("MMAMA")
   end
 
   def test_scales_with_specified_intervals_enigmatic
     skip
     scale = Scale.new("G")
-    assert_equal ["G", "G#", "B", "C#", "D#", "F", "F#"], scale.interval("mAMMMmm")
+    assert_equal ["G", "G#", "B", "C#", "D#", "F", "F#", "G"], scale.interval("mAMMMmm")
   end
 end