add ChordInvertTests

implements Chord.Invert() tests for common triads and seventh chords
michaldivis · Oct 31, 2023 · 07e5e7a · 07e5e7a
1 parent 5331b16
commit 07e5e7a
Showing 1 changed file with 152 additions and 0 deletions.
diff --git a/tests/DarkMusicConcepts.Tests/Chords/ChordInvertTests.cs b/tests/DarkMusicConcepts.Tests/Chords/ChordInvertTests.cs
@@ -0,0 +1,152 @@
+namespace DarkMusicConcepts;
+
+public class ChordInvertTests
+{
+    public static IEnumerable<Note> NotesUpTo7ThOctave => Notes.All.Where(a => a.Octave <= Octave.Seven);
+
+    public class InvertCommonTriadsTests
+    {
+        private static readonly ChordFormula[] commonTriads =
+        {
+            ChordFormulas.Major,
+            ChordFormulas.Minor,
+            ChordFormulas.Diminished,
+            ChordFormulas.Augmented
+        };
+
+        public static IEnumerable<object[]> CommonTriadsTestData
+        {
+            get
+            {
+                foreach (var chordFormula in commonTriads)
+                foreach (var rootNote in NotesUpTo7ThOctave)
+                    yield return new object[] { chordFormula, rootNote };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonTriadsTestData))]
+        public void Invert_Once_ShouldReturn_FirstInversion(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion1 = chord.Invert();
+
+            inversion1.Notes.Should().Equal(chord.Notes[1], chord.Notes[2], chord.Notes[0].TransposeUp(Intervals.PerfectOctave));
+            inversion1.Inversion.Should().Be(1);
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonTriadsTestData))]
+        public void Invert_Twice_ShouldReturn_SecondInversion(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion2 = chord.Invert().Invert();
+
+            inversion2.Notes.Should().Equal(chord.Notes[2], chord.Notes[0].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[1].TransposeUp(Intervals.PerfectOctave));
+            inversion2.Inversion.Should().Be(2);
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonTriadsTestData))]
+        public void Invert_ThreeTimes_ShouldReturn_InitialTriad_OneOctaveHigher(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion2 = chord.Invert().Invert().Invert();
+
+            inversion2.Notes.Should().Equal(
+                chord.Notes[0].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[1].TransposeUp(Intervals.PerfectOctave), chord.Notes[2].TransposeUp(Intervals.PerfectOctave));
+            inversion2.Inversion.Should().Be(0);
+        }
+    }
+
+    public class InvertCommonSeventhChordsTests
+    {
+        private static readonly ChordFormula[] commonTriads =
+        {
+            ChordFormulas.DominantSeventh,
+            ChordFormulas.MajorSeventh,
+            ChordFormulas.MinorSeventh,
+            ChordFormulas.MinorMajorSeventh,
+            ChordFormulas.DiminishedSeventh
+        };
+
+        public static IEnumerable<object[]> CommonSeventhChordsTestData
+        {
+            get
+            {
+                foreach (var chordFormula in commonTriads)
+                foreach (var rootNote in NotesUpTo7ThOctave)
+                    yield return new object[] { chordFormula, rootNote };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonSeventhChordsTestData))]
+        public void Invert_Once_ShouldReturn_FirstInversion(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion1 = chord.Invert();
+
+            inversion1.Notes.Should().Equal(
+                chord.Notes[1],
+                chord.Notes[2],
+                chord.Notes[3],
+                chord.Notes[0].TransposeUp(Intervals.PerfectOctave));
+            inversion1.Inversion.Should().Be(1);
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonSeventhChordsTestData))]
+        public void Invert_Twice_ShouldReturn_SecondInversion(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion2 = chord.Invert().Invert();
+
+            inversion2.Notes.Should().Equal(
+                chord.Notes[2],
+                chord.Notes[3],
+                chord.Notes[0].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[1].TransposeUp(Intervals.PerfectOctave));
+            inversion2.Inversion.Should().Be(2);
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonSeventhChordsTestData))]
+        public void Invert_ThreeTimes_ShouldReturn_ThirdInversion(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion2 = chord.Invert().Invert().Invert();
+
+            inversion2.Notes.Should().Equal(
+                chord.Notes[3],
+                chord.Notes[0].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[1].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[2].TransposeUp(Intervals.PerfectOctave));
+            inversion2.Inversion.Should().Be(3);
+        }
+
+        [Theory]
+        [MemberData(nameof(CommonSeventhChordsTestData))]
+        public void Invert_FourTimes_ShouldReturn_InitialSeventhChord_OneOctaveHigher(ChordFormula chordFormula, Note root)
+        {
+            var chord = Chord.Create(root, chordFormula);
+
+            var inversion2 = chord.Invert().Invert().Invert().Invert();
+
+            inversion2.Notes.Should().Equal(
+                chord.Notes[0].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[1].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[2].TransposeUp(Intervals.PerfectOctave),
+                chord.Notes[3].TransposeUp(Intervals.PerfectOctave));
+            inversion2.Inversion.Should().Be(0);
+        }
+    }
+}