fix: rgbToHsl no longer mutates its input array

rgbToHsl aliased its argument with colorHsl = colorRgb instead of
copying it, then overwrote colorHsl in place and returned that same
array, destroying the caller's original RGB values. Copy the input
with [...colorRgb] instead, and add a regression test asserting the
input is left unchanged.

Author: InukaWijerathna

Conversions/RgbHslConversion.js

@@ -22,7 +22,7 @@ const rgbToHsl = (colorRgb) => {
     throw new Error('Input is not a valid RGB color.')
   }
 
-  let colorHsl = colorRgb
+  let colorHsl = [...colorRgb]
 
   let red = Math.round(colorRgb[0])
   let green = Math.round(colorRgb[1])

Conversions/test/RgbHslConversion.test.js

@@ -40,4 +40,11 @@ describe('RgbHslConversion', () => {
   ])('Should return the error message.', (colorRgb, expected) => {
     expect(() => rgbToHsl(colorRgb)).toThrowError(expected)
   })
+
+  test('Should not mutate the input array.', () => {
+    const colorRgb = [24, 98, 118]
+    const result = rgbToHsl(colorRgb)
+    expect(colorRgb).toEqual([24, 98, 118])
+    expect(result).not.toBe(colorRgb)
+  })
 })