Fix the TeoriaInterval#octaves() method

saebekassebil · Jan 26, 2014 · 87b5f42 · 87b5f42
1 parent dd8e383
commit 87b5f42
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Showing 2 changed files with 25 additions and 2 deletions.
diff --git a/src/interval.js b/src/interval.js
@@ -68,8 +68,15 @@ TeoriaInterval.prototype = {
   },
 
   octaves: function() {
-    var without = sub(this.coord, mul(sharp, this.qualityValue()));
-    var octaves = without[0] - intervals[this.base()][0];
+    var without, octaves;
+
+    if (this.direction() === 'up') {
+      without = sub(this.coord, mul(sharp, this.qualityValue()));
+      octaves = without[0] - intervals[this.base()][0];
+    } else {
+      without = sub(this.coord, mul(sharp, -this.qualityValue()));
+      octaves = -(without[0] + intervals[this.base()][0]);
+    }
 
     return octaves;
   },

diff --git a/test/intervals.js b/test/intervals.js
@@ -322,6 +322,22 @@ vows.describe('Intervals').addBatch({
       assert.equal(teoria.interval('P22').octaves(), 2);
     },
 
+    'A descending fourth has no compound octaves': function() {
+      assert.equal(teoria.interval('P-4').octaves(), 0);
+    },
+
+    'A descending eleventh has one compound octave': function() {
+      assert.equal(teoria.interval('P-11').octaves(), 1);
+    },
+
+    'A descending augmented third has no compound octaves': function() {
+      assert.equal(teoria.interval('A-3').octaves(), 0);
+    },
+
+    'A descending major 16th has two compound octaves': function() {
+      assert.equal(teoria.interval('M-16').octaves(), 2);
+    },
+
     'A major seventh is greater than a minor seventh': function() {
       assert.equal(teoria.interval('M7').greater(teoria.interval('m7')), true);
     },