Refactor: add color type helper

src/color/hslToColorString.js

@@ -2,6 +2,7 @@
 import hsl from './hsl'
 import hsla from './hsla'
 import PolishedError from '../internalHelpers/_errors'
+import colorObjectType from '../internalHelpers/_colorObjectType'
 
 import type { HslColor, HslaColor } from '../types/color'
 
@@ -29,28 +30,24 @@ import type { HslColor, HslaColor } from '../types/color'
  *   background: "rgba(179,25,25,0.72)";
  * }
  */
-export default function hslToColorString(color: HslColor | HslaColor | number): string {
-  if (
-    typeof color === 'object'
-    && typeof color.hue === 'number'
-    && typeof color.saturation === 'number'
-    && typeof color.lightness === 'number'
-  ) {
-    if (color.alpha && typeof color.alpha === 'number') {
-      return hsla({
-        hue: color.hue,
-        saturation: color.saturation,
-        lightness: color.lightness,
-        alpha: color.alpha,
-      })
-    }
+export default function hslToColorString(color: HslColor | HslaColor): string {
+  const colorType = colorObjectType({
+    color,
+    expectedTypes: ['hsl', 'hsla'],
+    typeError: new PolishedError(45),
+  })
 
-    return hsl({
-      hue: color.hue,
-      saturation: color.saturation,
-      lightness: color.lightness,
+  if (colorType === 'hsla') {
+    const hslaColor: HslaColor = (color: any)
+    return hsla({
+      hue: hslaColor.hue,
+      saturation: hslaColor.saturation,
+      lightness: hslaColor.lightness,
+      alpha: hslaColor.alpha,
     })
   }
 
-  throw new PolishedError(45)
+  return hsl({
+    hue: color.hue, saturation: color.saturation, lightness: color.lightness,
+  })
 }

src/color/rgbToColorString.js

@@ -2,6 +2,7 @@
 import rgb from './rgb'
 import rgba from './rgba'
 import PolishedError from '../internalHelpers/_errors'
+import colorObjectType from '../internalHelpers/_colorObjectType'
 
 import type { RgbColor, RgbaColor } from '../types/color'
 
@@ -30,23 +31,21 @@ import type { RgbColor, RgbaColor } from '../types/color'
  * }
  */
 export default function rgbToColorString(color: RgbColor | RgbaColor): string {
-  if (
-    typeof color === 'object'
-    && typeof color.red === 'number'
-    && typeof color.green === 'number'
-    && typeof color.blue === 'number'
-  ) {
-    if (typeof color.alpha === 'number') {
-      return rgba({
-        red: color.red,
-        green: color.green,
-        blue: color.blue,
-        alpha: color.alpha,
-      })
-    }
+  const colorType = colorObjectType({
+    color,
+    expectedTypes: ['rgb', 'rgba'],
+    typeError: new PolishedError(46),
+  })
 
-    return rgb({ red: color.red, green: color.green, blue: color.blue })
+  if (colorType === 'rgba') {
+    const rgbaColor: RgbaColor = (color: any)
+    return rgba({
+      red: rgbaColor.red,
+      green: rgbaColor.green,
+      blue: rgbaColor.blue,
+      alpha: rgbaColor.alpha,
+    })
   }
 
-  throw new PolishedError(46)
+  return rgb({ red: color.red, green: color.green, blue: color.blue })
 }

src/color/toColorString.js

@@ -4,26 +4,7 @@ import hsla from './hsla'
 import rgb from './rgb'
 import rgba from './rgba'
 import PolishedError from '../internalHelpers/_errors'
-
-const isRgb = (color: Object): boolean => typeof color.red === 'number'
-  && typeof color.green === 'number'
-  && typeof color.blue === 'number'
-  && (typeof color.alpha !== 'number' || typeof color.alpha === 'undefined')
-
-const isRgba = (color: Object): boolean => typeof color.red === 'number'
-  && typeof color.green === 'number'
-  && typeof color.blue === 'number'
-  && typeof color.alpha === 'number'
-
-const isHsl = (color: Object): boolean => typeof color.hue === 'number'
-  && typeof color.saturation === 'number'
-  && typeof color.lightness === 'number'
-  && (typeof color.alpha !== 'number' || typeof color.alpha === 'undefined')
-
-const isHsla = (color: Object): boolean => typeof color.hue === 'number'
-  && typeof color.saturation === 'number'
-  && typeof color.lightness === 'number'
-  && typeof color.alpha === 'number'
+import colorObjectType from '../internalHelpers/_colorObjectType'
 
 /**
  * Converts a RgbColor, RgbaColor, HslColor or HslaColor object to a color string.
@@ -57,11 +38,15 @@ const isHsla = (color: Object): boolean => typeof color.hue === 'number'
  */
 
 export default function toColorString(color: Object): string {
-  if (typeof color !== 'object') throw new PolishedError(8)
-  if (isRgba(color)) return rgba(color)
-  if (isRgb(color)) return rgb(color)
-  if (isHsla(color)) return hsla(color)
-  if (isHsl(color)) return hsl(color)
+  const colorType = colorObjectType({
+    color,
+    expectedTypes: ['rgb', 'rgba', 'hsl', 'hsla'],
+    typeError: new PolishedError(8),
+  })
+
+  if (colorType === 'rgba') return rgba(color)
+  if (colorType === 'rgb') return rgb(color)
+  if (colorType === 'hsla') return hsla(color)
 
-  throw new PolishedError(8)
+  return hsl(color)
 }

src/internalHelpers/_colorObjectType.js

@@ -0,0 +1,32 @@
+// @flow
+import PolishedError from './_errors'
+
+const TYPE_KEYS = {
+  rgb: ['red', 'green', 'blue'],
+  rgba: ['red', 'green', 'blue', 'alpha'],
+  hsl: ['hue', 'saturation', 'lightness'],
+  hsla: ['hue', 'saturation', 'lightness', 'alpha'],
+}
+
+const matchType = (color: Object, type: string) => {
+  const keys = TYPE_KEYS[type]
+  return keys.every(key => typeof color[key] === 'number')
+    && (typeof color.alpha === 'number' ? keys.indexOf('alpha') > -1 : true)
+}
+
+/**
+ * Check color object type
+ * @private
+ */
+export default function colorObjectType({
+  color,
+  expectedTypes = ['rgb', 'rgba', 'hsl', 'hsla'],
+  typeError = new PolishedError(8),
+}:{ color: Object, expectedTypes?: string[], typeError?: PolishedError }): string {
+  if (typeof color !== 'object') throw typeError
+
+  const matchedType = expectedTypes.find(type => matchType(color, type))
+  if (matchedType) return matchedType
+
+  throw typeError
+}

src/internalHelpers/test/_colorObjectType.test.js

@@ -0,0 +1,95 @@
+// @flow
+import colorObjectType from '../_colorObjectType'
+import MockedError from '../_errors'
+
+jest.mock('../_errors', () => jest.fn().mockImplementation((errorNumber = 0) => new Error(`Error ${errorNumber}`)))
+
+const DEFAULT_TYPE_ERROR = 'Error 8'
+
+describe('colorObjectType', () => {
+  it('identifies color object type', () => {
+    expect(colorObjectType({
+      color: { red: 255, green: 205, blue: 100 },
+    })).toEqual('rgb')
+
+    expect(colorObjectType({
+      color: {
+        red: 255, green: 205, blue: 100, alpha: 0.5,
+      },
+    })).toEqual('rgba')
+
+    expect(colorObjectType({
+      color: { hue: 100, saturation: 0.5, lightness: 0.5 },
+    })).toEqual('hsl')
+
+    expect(colorObjectType({
+      color: {
+        hue: 100, saturation: 0.5, lightness: 0.5, alpha: 0.5,
+      },
+    })).toEqual('hsla')
+  })
+
+  it('throws error if color object is invalid', () => {
+    expect(() => colorObjectType({
+      color: {
+        not: 123, a: 123, color: 123,
+      },
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+
+    expect(() => colorObjectType({
+      color: {
+        red: 255, green: 205, notBlue: 123,
+      },
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+
+    expect(() => colorObjectType({
+      color: {},
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+  })
+
+  it('throws error if color object is missing', () => {
+    expect(() => colorObjectType({ color: undefined })).toThrowError(DEFAULT_TYPE_ERROR)
+  })
+
+  it('throws error if color object is not an object', () => {
+    expect(() => colorObjectType({ color: 'not an object' })).toThrowError(DEFAULT_TYPE_ERROR)
+  })
+
+  it('throws error for unexpected color types', () => {
+    expect(() => colorObjectType({
+      color: { red: 255, green: 205, blue: 100 },
+      expectedTypes: ['hsl', 'hsla'],
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+
+    expect(() => colorObjectType({
+      color: { hue: 100, saturation: 0.5, lightness: 0.5 },
+      expectedTypes: ['rgb', 'rgba'],
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+
+    expect(() => colorObjectType({
+      color: { hue: 100, saturation: 0.5, lightness: 0.5 },
+      expectedTypes: ['hsla'],
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+
+    expect(() => colorObjectType({
+      color: { red: 255, green: 205, blue: 100 },
+      expectedTypes: ['rgba'],
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+
+    expect(() => colorObjectType({
+      color: {
+        red: 255, green: 205, blue: 100, alpha: 0.5,
+      },
+      expectedTypes: ['rgb'],
+    })).toThrowError(DEFAULT_TYPE_ERROR)
+  })
+
+  it('throws custom errors', () => {
+    expect(() => colorObjectType({
+      color: {
+        not: 123, a: 123, color: 123,
+      },
+      typeError: new MockedError(99),
+    })).toThrowError('Error 99')
+  })
+})