add colorMixCMYK tests

tests/color/colorMixCMYK.test.ts

@@ -0,0 +1,37 @@
+import * as _ from 'radashi'
+import { Color } from 'radashi'
+
+describe('colorMixCMYK', () => {
+  test('mixes black and white', () => {
+    expect(_.colorMixCMYK('#000000', '#FFFFFF', 0.5)).toEqual(
+      new Color(0.5, 0.5, 0.5, 1),
+    )
+  })
+  test('mixes blue and yellow', () => {
+    expect(_.colorMixCMYK('#0000FF', '#FFFF00', 0.5)).toEqual(
+      new Color(0.5, 0.5, 0.5, 1),
+    )
+  })
+  test('mixes red and green with different ratios', () => {
+    expect(_.colorMixCMYK('#FF0000', '#00FF00', 0.25)).toEqual(
+      new Color(0.75, 0, 0.25, 1),
+    )
+    expect(_.colorMixCMYK('#FF0000', '#00FF00', 0.75)).toEqual(
+      new Color(0.25, 0, 0.75, 1),
+    )
+  })
+  test('handles alpha channel', () => {
+    expect(_.colorMixCMYK('#FF0000', '#00FF0000', 0.5)).toEqual(
+      new Color(0.5, 0, 0.5, 0.5),
+    )
+  })
+  test('mixes CMYK colors', () => {
+    expect(
+      _.colorMixCMYK(
+        { cyan: 0, magenta: 1, yellow: 0.75, key: 0.5, alpha: 1 },
+        { cyan: 1, magenta: 0.5, yellow: 0.25, key: 0, alpha: 1 },
+        0.5,
+      ),
+    ).toEqual(new Color(0.375, 0.375, 0.1875, 1))
+  })
+})