diff --git a/test/unit/color/hsb.js b/test/unit/color/hsb.js
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+/**
+ * Tests for the HSB (Hue, Saturation, Brightness) color space.
+ *
+ * The HSB color space is defined in src/color/color_spaces/hsb.js and provides
+ * conversions between RGB (base) and HSB color representations.
+ *
+ * HSB ranges:
+ * - Hue: 0-360 (degrees on color wheel)
+ * - Saturation: 0-100 (percentage)
+ * - Brightness: 0-100 (percentage)
+ *
+ * RGB ranges (in colorjs.io):
+ * - R, G, B: 0-1 (normalized)
+ */
+
+import HSBSpace from '../../../src/color/color_spaces/hsb.js';
+
+suite('color/HSB Color Space', function() {
+  const accuracy = 0.01;
+
+  suite('HSB to RGB conversion (toBase)', function() {
+    suite('Primary Colors', function() {
+      test('pure red: HSB(0, 100, 100) → RGB(1, 0, 0)', function() {
+        const result = HSBSpace.toBase([0, 100, 100]);
+        assert.approximately(result[0], 1, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+
+      test('pure green: HSB(120, 100, 100) → RGB(0, 1, 0)', function() {
+        const result = HSBSpace.toBase([120, 100, 100]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 1, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+
+      test('pure blue: HSB(240, 100, 100) → RGB(0, 0, 1)', function() {
+        const result = HSBSpace.toBase([240, 100, 100]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 1, accuracy);
+      });
+    });
+
+    suite('Secondary Colors', function() {
+      test('yellow: HSB(60, 100, 100) → RGB(1, 1, 0)', function() {
+        const result = HSBSpace.toBase([60, 100, 100]);
+        assert.approximately(result[0], 1, accuracy);
+        assert.approximately(result[1], 1, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+
+      test('cyan: HSB(180, 100, 100) → RGB(0, 1, 1)', function() {
+        const result = HSBSpace.toBase([180, 100, 100]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 1, accuracy);
+        assert.approximately(result[2], 1, accuracy);
+      });
+
+      test('magenta: HSB(300, 100, 100) → RGB(1, 0, 1)', function() {
+        const result = HSBSpace.toBase([300, 100, 100]);
+        assert.approximately(result[0], 1, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 1, accuracy);
+      });
+    });
+
+    suite('Grayscale (Saturation = 0)', function() {
+      test('white: HSB(0, 0, 100) → RGB(1, 1, 1)', function() {
+        const result = HSBSpace.toBase([0, 0, 100]);
+        assert.approximately(result[0], 1, accuracy);
+        assert.approximately(result[1], 1, accuracy);
+        assert.approximately(result[2], 1, accuracy);
+      });
+
+      test('black: HSB(0, 0, 0) → RGB(0, 0, 0)', function() {
+        const result = HSBSpace.toBase([0, 0, 0]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+
+      test('mid gray: HSB(0, 0, 50) → RGB(0.5, 0.5, 0.5)', function() {
+        const result = HSBSpace.toBase([0, 0, 50]);
+        assert.approximately(result[0], 0.5, accuracy);
+        assert.approximately(result[1], 0.5, accuracy);
+        assert.approximately(result[2], 0.5, accuracy);
+      });
+
+      test('grayscale ignores hue: HSB(180, 0, 50) → RGB(0.5, 0.5, 0.5)', function() {
+        const result = HSBSpace.toBase([180, 0, 50]);
+        assert.approximately(result[0], 0.5, accuracy);
+        assert.approximately(result[1], 0.5, accuracy);
+        assert.approximately(result[2], 0.5, accuracy);
+      });
+    });
+
+    suite('Partial Saturation', function() {
+      test('50% saturation red: HSB(0, 50, 100) → RGB(1, 0.5, 0.5)', function() {
+        const result = HSBSpace.toBase([0, 50, 100]);
+        assert.approximately(result[0], 1, accuracy);
+        assert.approximately(result[1], 0.5, accuracy);
+        assert.approximately(result[2], 0.5, accuracy);
+      });
+
+      test('50% brightness red: HSB(0, 100, 50) → RGB(0.5, 0, 0)', function() {
+        const result = HSBSpace.toBase([0, 100, 50]);
+        assert.approximately(result[0], 0.5, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+    });
+
+    suite('Edge Cases', function() {
+      test('hue at 360 should be same as 0 (red)', function() {
+        const result = HSBSpace.toBase([360, 100, 100]);
+        assert.approximately(result[0], 1, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+
+      test('brightness 0 produces black regardless of hue/saturation', function() {
+        const result = HSBSpace.toBase([120, 100, 0]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+    });
+  });
+
+  suite('RGB to HSB conversion (fromBase)', function() {
+    suite('Primary Colors', function() {
+      test('pure red: RGB(1, 0, 0) → HSB(0, 100, 100)', function() {
+        const result = HSBSpace.fromBase([1, 0, 0]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+
+      test('pure green: RGB(0, 1, 0) → HSB(120, 100, 100)', function() {
+        const result = HSBSpace.fromBase([0, 1, 0]);
+        assert.approximately(result[0], 120, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+
+      test('pure blue: RGB(0, 0, 1) → HSB(240, 100, 100)', function() {
+        const result = HSBSpace.fromBase([0, 0, 1]);
+        assert.approximately(result[0], 240, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+    });
+
+    suite('Secondary Colors', function() {
+      test('yellow: RGB(1, 1, 0) → HSB(60, 100, 100)', function() {
+        const result = HSBSpace.fromBase([1, 1, 0]);
+        assert.approximately(result[0], 60, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+
+      test('cyan: RGB(0, 1, 1) → HSB(180, 100, 100)', function() {
+        const result = HSBSpace.fromBase([0, 1, 1]);
+        assert.approximately(result[0], 180, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+
+      test('magenta: RGB(1, 0, 1) → HSB(300, 100, 100)', function() {
+        const result = HSBSpace.fromBase([1, 0, 1]);
+        assert.approximately(result[0], 300, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+    });
+
+    suite('Grayscale', function() {
+      test('white: RGB(1, 1, 1) → HSB(0, 0, 100)', function() {
+        const result = HSBSpace.fromBase([1, 1, 1]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+
+      test('black: RGB(0, 0, 0) → HSB(0, 0, 0)', function() {
+        const result = HSBSpace.fromBase([0, 0, 0]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 0, accuracy);
+      });
+
+      test('mid gray: RGB(0.5, 0.5, 0.5) → HSB(0, 0, 50)', function() {
+        const result = HSBSpace.fromBase([0.5, 0.5, 0.5]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 0, accuracy);
+        assert.approximately(result[2], 50, accuracy);
+      });
+    });
+
+    suite('Partial Values', function() {
+      test('dark red: RGB(0.5, 0, 0) → HSB(0, 100, 50)', function() {
+        const result = HSBSpace.fromBase([0.5, 0, 0]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 100, accuracy);
+        assert.approximately(result[2], 50, accuracy);
+      });
+
+      test('light red (pink): RGB(1, 0.5, 0.5) → HSB(0, 50, 100)', function() {
+        const result = HSBSpace.fromBase([1, 0.5, 0.5]);
+        assert.approximately(result[0], 0, accuracy);
+        assert.approximately(result[1], 50, accuracy);
+        assert.approximately(result[2], 100, accuracy);
+      });
+    });
+  });
+
+  suite('Round-trip conversion', function() {
+    test('HSB → RGB → HSB should preserve values', function() {
+      const originalHSB = [210, 75, 80];
+      const rgb = HSBSpace.toBase(originalHSB);
+      const resultHSB = HSBSpace.fromBase(rgb);
+
+      assert.approximately(resultHSB[0], originalHSB[0], 0.1);
+      assert.approximately(resultHSB[1], originalHSB[1], 0.1);
+      assert.approximately(resultHSB[2], originalHSB[2], 0.1);
+    });
+
+    test('RGB → HSB → RGB should preserve values', function() {
+      const originalRGB = [0.7, 0.3, 0.5];
+      const hsb = HSBSpace.fromBase(originalRGB);
+      const resultRGB = HSBSpace.toBase(hsb);
+
+      assert.approximately(resultRGB[0], originalRGB[0], 0.01);
+      assert.approximately(resultRGB[1], originalRGB[1], 0.01);
+      assert.approximately(resultRGB[2], originalRGB[2], 0.01);
+    });
+  });
+});