diff --git a/pygal/colors.py b/pygal/colors.py
new file mode 100644
index 0000000..4c08f7c
--- /dev/null
+++ b/pygal/colors.py
@@ -0,0 +1,122 @@
+# -*- coding: utf-8 -*-
+# This file is part of pygal
+#
+# A python svg graph plotting library
+# Copyright © 2012-2013 Kozea
+#
+# This library is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option) any
+# later version.
+#
+# This library is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with pygal. If not, see <http://www.gnu.org/licenses/>.
+"""
+Color utils
+
+"""
+from __future__ import division
+
+
+def normalize_float(f):
+    if abs(f - round(f)) < .0000000000001:
+        return round(f)
+    return f
+
+
+def rgb_to_hsl(r, g, b):
+    r /= 255
+    g /= 255
+    b /= 255
+    max_ = max((r, g, b))
+    min_ = min((r, g, b))
+    d = max_ - min_
+
+    if not d:
+        h = 0
+    elif r is max_:
+        h = 60 * (g - b) / d
+    elif g is max_:
+        h = 60 * (b - r) / d + 120
+    else:
+        h = 60 * (r - g) / d + 240
+
+    l = .5 * (max_ + min_)
+    if not d:
+        s = 0
+    elif l < 0.5:
+        s = .5 * d / l
+    else:
+        s = .5 * d / (1 - l)
+    return tuple(map(normalize_float, (h % 360, s * 100, l * 100)))
+
+
+def hsl_to_rgb(h, s, l):
+    h /= 360
+    s /= 100
+    l /= 100
+
+    m2 = l * (s + 1) if l <= .5 else l + s - l * s
+    m1 = 2 * l - m2
+
+    def h_to_rgb(h):
+        h = h % 1
+        if 6 * h < 1:
+            return m1 + 6 * h * (m2 - m1)
+        if 2 * h < 1:
+            return m2
+        if 3 * h < 2:
+            return m1 + 6 * (2 / 3 - h) * (m2 - m1)
+        return m1
+    r, g, b = map(lambda x: round(x * 255),
+                  map(h_to_rgb, (h + 1 / 3, h, h - 1 / 3)))
+
+    return r, g, b
+
+
+def adjust(color, attribute, percent):
+    assert color[0] == '#', '#rrggbb and #rgb format are supported'
+    color = color[1:]
+    assert len(color) in (3, 6), '#rrggbb and #rgb format are supported'
+    if len(color) == 3:
+        color = [a for b in zip(color, color) for a in b]
+
+    bound = lambda x: max(0, min(100, x))
+
+    def _adjust(hsl):
+        hsl = list(hsl)
+        if attribute > 0:
+            hsl[attribute] = bound(hsl[attribute] + percent)
+        else:
+            hsl[attribute] += percent
+
+        return hsl
+    return '#%02x%02x%02x' % hsl_to_rgb(
+        *_adjust(
+            rgb_to_hsl(*map(lambda x: int(''.join(x), 16),
+                            zip(color[::2], color[1::2])))))
+
+
+def rotate(color, percent):
+    return adjust(color, 0, percent)
+
+
+def saturate(color, percent):
+    return adjust(color, 1, percent)
+
+
+def desaturate(color, percent):
+    return adjust(color, 1, -percent)
+
+
+def lighten(color, percent):
+    return adjust(color, 2, percent)
+
+
+def darken(color, percent):
+    return adjust(color, 2, -percent)
diff --git a/pygal/style.py b/pygal/style.py
index 7e2d477..50f9846 100644
--- a/pygal/style.py
+++ b/pygal/style.py
@@ -20,23 +20,7 @@
 Charts styling
 """
 from __future__ import division
-from pygal.util import cycle_fill, rgb_to_hsl, hsl_to_rgb
-
-
-def darken(color, percent):
-    assert color[0] == '#', '#rrggbb and #rgb format are supported'
-    color = color[1:]
-    assert len(color) in (3, 6), '#rrggbb and #rgb format are supported'
-    if len(color) == 3:
-        color = [a for b in zip(color, color) for a in b]
-    return '#%02x%02x%02x' % hsl_to_rgb(
-        *(lambda h, s, l: (h, s, max(0, min(100, l - percent))))(
-            *rgb_to_hsl(*map(lambda x: int(''.join(x), 16),
-                             zip(color[::2], color[1::2])))))
-
-
-def lighten(color, percent):
-    return darken(color, -percent)
+from pygal.util import cycle_fill
 
 
 class Style(object):
diff --git a/pygal/test/test_colors.py b/pygal/test/test_colors.py
new file mode 100644
index 0000000..c60f72b
--- /dev/null
+++ b/pygal/test/test_colors.py
@@ -0,0 +1,446 @@
+from pygal.colors import (
+    rgb_to_hsl, hsl_to_rgb, darken, lighten, saturate, desaturate, rotate)
+
+
+def test_darken():
+    assert darken('#800', 20) == '#220000'
+    assert darken('#800', 0) == '#880000'
+    assert darken('#ffffff', 10) == '#e6e6e6'
+    assert darken('#000000', 10) == '#000000'
+    assert darken('#f3148a', 25) == '#810747'
+    assert darken('#121212', 1) == '#0f0f0f'
+    assert darken('#999999', 100) == '#000000'
+    assert darken('#1479ac', 8) == '#105f87'
+
+
+def test_lighten():
+    assert lighten('#800', 20) == '#ee0000'
+    assert lighten('#800', 0) == '#880000'
+    assert lighten('#ffffff', 10) == '#ffffff'
+    assert lighten('#000000', 10) == '#1a1a1a'
+    assert lighten('#f3148a', 25) == '#f98dc6'
+    assert lighten('#121212', 1) == '#151515'
+    assert lighten('#999999', 100) == '#ffffff'
+    assert lighten('#1479ac', 8) == '#1893d1'
+
+
+def test_saturate():
+    assert saturate('#000', 20) == '#000000'
+    assert saturate('#fff', 20) == '#ffffff'
+    assert saturate('#8a8', 100) == '#33ff33'
+    assert saturate('#855', 20) == '#9e3f3f'
+
+
+def test_desaturate():
+    assert desaturate('#000', 20) == '#000000'
+    assert desaturate('#fff', 20) == '#ffffff'
+    assert desaturate('#8a8', 100) == '#999999'
+    assert desaturate('#855', 20) == '#726b6b'
+
+
+def test_rotate():
+    assert rotate('#000', 45) == '#000000'
+    assert rotate('#fff', 45) == '#ffffff'
+    assert rotate('#811', 45) == '#886a11'
+    assert rotate('#8a8', 360) == '#88aa88'
+    assert rotate('#8a8', 0) == '#88aa88'
+    assert rotate('#8a8', -360) == '#88aa88'
+
+
+def test_hsl_to_rgb_part_0():
+    assert hsl_to_rgb(0, 100, 50) == (255, 0, 0)
+    assert hsl_to_rgb(60, 100, 50) == (255, 255, 0)
+    assert hsl_to_rgb(120, 100, 50) == (0, 255, 0)
+    assert hsl_to_rgb(180, 100, 50) == (0, 255, 255)
+    assert hsl_to_rgb(240, 100, 50) == (0, 0, 255)
+    assert hsl_to_rgb(300, 100, 50) == (255, 0, 255)
+
+
+def test_rgb_to_hsl_part_0():
+    assert rgb_to_hsl(255, 0, 0) == (0, 100, 50)
+    assert rgb_to_hsl(255, 255, 0) == (60, 100, 50)
+    assert rgb_to_hsl(0, 255, 0) == (120, 100, 50)
+    assert rgb_to_hsl(0, 255, 255) == (180, 100, 50)
+    assert rgb_to_hsl(0, 0, 255) == (240, 100, 50)
+    assert rgb_to_hsl(255, 0, 255) == (300, 100, 50)
+
+
+def test_hsl_to_rgb_part_1():
+    assert hsl_to_rgb(-360, 100, 50) == (255, 0, 0)
+    assert hsl_to_rgb(-300, 100, 50) == (255, 255, 0)
+    assert hsl_to_rgb(-240, 100, 50) == (0, 255, 0)
+    assert hsl_to_rgb(-180, 100, 50) == (0, 255, 255)
+    assert hsl_to_rgb(-120, 100, 50) == (0, 0, 255)
+    assert hsl_to_rgb(-60, 100, 50) == (255, 0, 255)
+
+
+def test_rgb_to_hsl_part_1():
+    # assert rgb_to_hsl(255, 0, 0) == (-360, 100, 50)
+    # assert rgb_to_hsl(255, 255, 0) == (-300, 100, 50)
+    # assert rgb_to_hsl(0, 255, 0) == (-240, 100, 50)
+    # assert rgb_to_hsl(0, 255, 255) == (-180, 100, 50)
+    # assert rgb_to_hsl(0, 0, 255) == (-120, 100, 50)
+    # assert rgb_to_hsl(255, 0, 255) == (-60, 100, 50)
+    pass
+
+
+def test_hsl_to_rgb_part_2():
+    assert hsl_to_rgb(360, 100, 50) == (255, 0, 0)
+    assert hsl_to_rgb(420, 100, 50) == (255, 255, 0)
+    assert hsl_to_rgb(480, 100, 50) == (0, 255, 0)
+    assert hsl_to_rgb(540, 100, 50) == (0, 255, 255)
+    assert hsl_to_rgb(600, 100, 50) == (0, 0, 255)
+    assert hsl_to_rgb(660, 100, 50) == (255, 0, 255)
+
+
+def test_rgb_to_hsl_part_2():
+    # assert rgb_to_hsl(255, 0, 0) == (360, 100, 50)
+    # assert rgb_to_hsl(255, 255, 0) == (420, 100, 50)
+    # assert rgb_to_hsl(0, 255, 0) == (480, 100, 50)
+    # assert rgb_to_hsl(0, 255, 255) == (540, 100, 50)
+    # assert rgb_to_hsl(0, 0, 255) == (600, 100, 50)
+    # assert rgb_to_hsl(255, 0, 255) == (660, 100, 50)
+    pass
+
+
+def test_hsl_to_rgb_part_3():
+    assert hsl_to_rgb(6120, 100, 50) == (255, 0, 0)
+    assert hsl_to_rgb(-9660, 100, 50) == (255, 255, 0)
+    assert hsl_to_rgb(99840, 100, 50) == (0, 255, 0)
+    assert hsl_to_rgb(-900, 100, 50) == (0, 255, 255)
+    assert hsl_to_rgb(-104880, 100, 50) == (0, 0, 255)
+    assert hsl_to_rgb(2820, 100, 50) == (255, 0, 255)
+
+
+def test_rgb_to_hsl_part_3():
+    # assert rgb_to_hsl(255, 0, 0) == (6120, 100, 50)
+    # assert rgb_to_hsl(255, 255, 0) == (-9660, 100, 50)
+    # assert rgb_to_hsl(0, 255, 0) == (99840, 100, 50)
+    # assert rgb_to_hsl(0, 255, 255) == (-900, 100, 50)
+    # assert rgb_to_hsl(0, 0, 255) == (-104880, 100, 50)
+    # assert rgb_to_hsl(255, 0, 255) == (2820, 100, 50)
+    pass
+
+
+def test_hsl_to_rgb_part_4():
+    assert hsl_to_rgb(0, 100, 50) == (255, 0, 0)
+    assert hsl_to_rgb(12, 100, 50) == (255, 51, 0)
+    assert hsl_to_rgb(24, 100, 50) == (255, 102, 0)
+    assert hsl_to_rgb(36, 100, 50) == (255, 153, 0)
+    assert hsl_to_rgb(48, 100, 50) == (255, 204, 0)
+    assert hsl_to_rgb(60, 100, 50) == (255, 255, 0)
+    assert hsl_to_rgb(72, 100, 50) == (204, 255, 0)
+    assert hsl_to_rgb(84, 100, 50) == (153, 255, 0)
+    assert hsl_to_rgb(96, 100, 50) == (102, 255, 0)
+    assert hsl_to_rgb(108, 100, 50) == (51, 255, 0)
+    assert hsl_to_rgb(120, 100, 50) == (0, 255, 0)
+
+
+def test_rgb_to_hsl_part_4():
+    assert rgb_to_hsl(255, 0, 0) == (0, 100, 50)
+    assert rgb_to_hsl(255, 51, 0) == (12, 100, 50)
+    assert rgb_to_hsl(255, 102, 0) == (24, 100, 50)
+    assert rgb_to_hsl(255, 153, 0) == (36, 100, 50)
+    assert rgb_to_hsl(255, 204, 0) == (48, 100, 50)
+    assert rgb_to_hsl(255, 255, 0) == (60, 100, 50)
+    assert rgb_to_hsl(204, 255, 0) == (72, 100, 50)
+    assert rgb_to_hsl(153, 255, 0) == (84, 100, 50)
+    assert rgb_to_hsl(102, 255, 0) == (96, 100, 50)
+    assert rgb_to_hsl(51, 255, 0) == (108, 100, 50)
+    assert rgb_to_hsl(0, 255, 0) == (120, 100, 50)
+
+
+def test_hsl_to_rgb_part_5():
+    assert hsl_to_rgb(120, 100, 50) == (0, 255, 0)
+    assert hsl_to_rgb(132, 100, 50) == (0, 255, 51)
+    assert hsl_to_rgb(144, 100, 50) == (0, 255, 102)
+    assert hsl_to_rgb(156, 100, 50) == (0, 255, 153)
+    assert hsl_to_rgb(168, 100, 50) == (0, 255, 204)
+    assert hsl_to_rgb(180, 100, 50) == (0, 255, 255)
+    assert hsl_to_rgb(192, 100, 50) == (0, 204, 255)
+    assert hsl_to_rgb(204, 100, 50) == (0, 153, 255)
+    assert hsl_to_rgb(216, 100, 50) == (0, 102, 255)
+    assert hsl_to_rgb(228, 100, 50) == (0, 51, 255)
+    assert hsl_to_rgb(240, 100, 50) == (0, 0, 255)
+
+
+def test_rgb_to_hsl_part_5():
+    assert rgb_to_hsl(0, 255, 0) == (120, 100, 50)
+    assert rgb_to_hsl(0, 255, 51) == (132, 100, 50)
+    assert rgb_to_hsl(0, 255, 102) == (144, 100, 50)
+    assert rgb_to_hsl(0, 255, 153) == (156, 100, 50)
+    assert rgb_to_hsl(0, 255, 204) == (168, 100, 50)
+    assert rgb_to_hsl(0, 255, 255) == (180, 100, 50)
+    assert rgb_to_hsl(0, 204, 255) == (192, 100, 50)
+    assert rgb_to_hsl(0, 153, 255) == (204, 100, 50)
+    assert rgb_to_hsl(0, 102, 255) == (216, 100, 50)
+    assert rgb_to_hsl(0, 51, 255) == (228, 100, 50)
+    assert rgb_to_hsl(0, 0, 255) == (240, 100, 50)
+
+
+def test_hsl_to_rgb_part_6():
+    assert hsl_to_rgb(240, 100, 50) == (0, 0, 255)
+    assert hsl_to_rgb(252, 100, 50) == (51, 0, 255)
+    assert hsl_to_rgb(264, 100, 50) == (102, 0, 255)
+    assert hsl_to_rgb(276, 100, 50) == (153, 0, 255)
+    assert hsl_to_rgb(288, 100, 50) == (204, 0, 255)
+    assert hsl_to_rgb(300, 100, 50) == (255, 0, 255)
+    assert hsl_to_rgb(312, 100, 50) == (255, 0, 204)
+    assert hsl_to_rgb(324, 100, 50) == (255, 0, 153)
+    assert hsl_to_rgb(336, 100, 50) == (255, 0, 102)
+    assert hsl_to_rgb(348, 100, 50) == (255, 0, 51)
+    assert hsl_to_rgb(360, 100, 50) == (255, 0, 0)
+
+
+def test_rgb_to_hsl_part_6():
+    assert rgb_to_hsl(0, 0, 255) == (240, 100, 50)
+    assert rgb_to_hsl(51, 0, 255) == (252, 100, 50)
+    assert rgb_to_hsl(102, 0, 255) == (264, 100, 50)
+    assert rgb_to_hsl(153, 0, 255) == (276, 100, 50)
+    assert rgb_to_hsl(204, 0, 255) == (288, 100, 50)
+    assert rgb_to_hsl(255, 0, 255) == (300, 100, 50)
+    assert rgb_to_hsl(255, 0, 204) == (312, 100, 50)
+    assert rgb_to_hsl(255, 0, 153) == (324, 100, 50)
+    assert rgb_to_hsl(255, 0, 102) == (336, 100, 50)
+    assert rgb_to_hsl(255, 0, 51) == (348, 100, 50)
+    # assert rgb_to_hsl(255, 0, 0) == (360, 100, 50)
+
+
+def test_hsl_to_rgb_part_7():
+    assert hsl_to_rgb(0, 20, 50) == (153, 102, 102)
+    assert hsl_to_rgb(0, 60, 50) == (204, 51, 51)
+    assert hsl_to_rgb(0, 100, 50) == (255, 0, 0)
+
+
+def test_rgb_to_hsl_part_7():
+    assert rgb_to_hsl(153, 102, 102) == (0, 20, 50)
+    assert rgb_to_hsl(204, 51, 51) == (0, 60, 50)
+    assert rgb_to_hsl(255, 0, 0) == (0, 100, 50)
+
+
+def test_hsl_to_rgb_part_8():
+    assert hsl_to_rgb(60, 20, 50) == (153, 153, 102)
+    assert hsl_to_rgb(60, 60, 50) == (204, 204, 51)
+    assert hsl_to_rgb(60, 100, 50) == (255, 255, 0)
+
+
+def test_rgb_to_hsl_part_8():
+    assert rgb_to_hsl(153, 153, 102) == (60, 20, 50)
+    assert rgb_to_hsl(204, 204, 51) == (60, 60, 50)
+    assert rgb_to_hsl(255, 255, 0) == (60, 100, 50)
+
+
+def test_hsl_to_rgb_part_9():
+    assert hsl_to_rgb(120, 20, 50) == (102, 153, 102)
+    assert hsl_to_rgb(120, 60, 50) == (51, 204, 51)
+    assert hsl_to_rgb(120, 100, 50) == (0, 255, 0)
+
+
+def test_rgb_to_hsl_part_9():
+    assert rgb_to_hsl(102, 153, 102) == (120, 20, 50)
+    assert rgb_to_hsl(51, 204, 51) == (120, 60, 50)
+    assert rgb_to_hsl(0, 255, 0) == (120, 100, 50)
+
+
+def test_hsl_to_rgb_part_10():
+    assert hsl_to_rgb(180, 20, 50) == (102, 153, 153)
+    assert hsl_to_rgb(180, 60, 50) == (51, 204, 204)
+    assert hsl_to_rgb(180, 100, 50) == (0, 255, 255)
+
+
+def test_rgb_to_hsl_part_10():
+    assert rgb_to_hsl(102, 153, 153) == (180, 20, 50)
+    assert rgb_to_hsl(51, 204, 204) == (180, 60, 50)
+    assert rgb_to_hsl(0, 255, 255) == (180, 100, 50)
+
+
+def test_hsl_to_rgb_part_11():
+    assert hsl_to_rgb(240, 20, 50) == (102, 102, 153)
+    assert hsl_to_rgb(240, 60, 50) == (51, 51, 204)
+    assert hsl_to_rgb(240, 100, 50) == (0, 0, 255)
+
+
+def test_rgb_to_hsl_part_11():
+    assert rgb_to_hsl(102, 102, 153) == (240, 20, 50)
+    assert rgb_to_hsl(51, 51, 204) == (240, 60, 50)
+    assert rgb_to_hsl(0, 0, 255) == (240, 100, 50)
+
+
+def test_hsl_to_rgb_part_12():
+    assert hsl_to_rgb(300, 20, 50) == (153, 102, 153)
+    assert hsl_to_rgb(300, 60, 50) == (204, 51, 204)
+    assert hsl_to_rgb(300, 100, 50) == (255, 0, 255)
+
+
+def test_rgb_to_hsl_part_12():
+    assert rgb_to_hsl(153, 102, 153) == (300, 20, 50)
+    assert rgb_to_hsl(204, 51, 204) == (300, 60, 50)
+    assert rgb_to_hsl(255, 0, 255) == (300, 100, 50)
+
+
+def test_hsl_to_rgb_part_13():
+    assert hsl_to_rgb(0, 100, 0) == (0, 0, 0)
+    assert hsl_to_rgb(0, 100, 10) == (51, 0, 0)
+    assert hsl_to_rgb(0, 100, 20) == (102, 0, 0)
+    assert hsl_to_rgb(0, 100, 30) == (153, 0, 0)
+    assert hsl_to_rgb(0, 100, 40) == (204, 0, 0)
+    assert hsl_to_rgb(0, 100, 50) == (255, 0, 0)
+    assert hsl_to_rgb(0, 100, 60) == (255, 51, 51)
+    assert hsl_to_rgb(0, 100, 70) == (255, 102, 102)
+    assert hsl_to_rgb(0, 100, 80) == (255, 153, 153)
+    assert hsl_to_rgb(0, 100, 90) == (255, 204, 204)
+    assert hsl_to_rgb(0, 100, 100) == (255, 255, 255)
+
+
+def test_rgb_to_hsl_part_13():
+    assert rgb_to_hsl(0, 0, 0) == (0, 0, 0)
+    assert rgb_to_hsl(51, 0, 0) == (0, 100, 10)
+    assert rgb_to_hsl(102, 0, 0) == (0, 100, 20)
+    assert rgb_to_hsl(153, 0, 0) == (0, 100, 30)
+    assert rgb_to_hsl(204, 0, 0) == (0, 100, 40)
+    assert rgb_to_hsl(255, 0, 0) == (0, 100, 50)
+    assert rgb_to_hsl(255, 51, 51) == (0, 100, 60)
+    assert rgb_to_hsl(255, 102, 102) == (0, 100, 70)
+    assert rgb_to_hsl(255, 153, 153) == (0, 100, 80)
+    assert rgb_to_hsl(255, 204, 204) == (0, 100, 90)
+    assert rgb_to_hsl(255, 255, 255) == (0, 0, 100)
+
+
+def test_hsl_to_rgb_part_14():
+    assert hsl_to_rgb(60, 100, 0) == (0, 0, 0)
+    assert hsl_to_rgb(60, 100, 10) == (51, 51, 0)
+    assert hsl_to_rgb(60, 100, 20) == (102, 102, 0)
+    assert hsl_to_rgb(60, 100, 30) == (153, 153, 0)
+    assert hsl_to_rgb(60, 100, 40) == (204, 204, 0)
+    assert hsl_to_rgb(60, 100, 50) == (255, 255, 0)
+    assert hsl_to_rgb(60, 100, 60) == (255, 255, 51)
+    assert hsl_to_rgb(60, 100, 70) == (255, 255, 102)
+    assert hsl_to_rgb(60, 100, 80) == (255, 255, 153)
+    assert hsl_to_rgb(60, 100, 90) == (255, 255, 204)
+    assert hsl_to_rgb(60, 100, 100) == (255, 255, 255)
+
+
+def test_rgb_to_hsl_part_14():
+    # assert rgb_to_hsl(0, 0, 0) == (60, 100, 0)
+    assert rgb_to_hsl(51, 51, 0) == (60, 100, 10)
+    assert rgb_to_hsl(102, 102, 0) == (60, 100, 20)
+    assert rgb_to_hsl(153, 153, 0) == (60, 100, 30)
+    assert rgb_to_hsl(204, 204, 0) == (60, 100, 40)
+    assert rgb_to_hsl(255, 255, 0) == (60, 100, 50)
+    assert rgb_to_hsl(255, 255, 51) == (60, 100, 60)
+    assert rgb_to_hsl(255, 255, 102) == (60, 100, 70)
+    assert rgb_to_hsl(255, 255, 153) == (60, 100, 80)
+    assert rgb_to_hsl(255, 255, 204) == (60, 100, 90)
+    # assert rgb_to_hsl(255, 255, 255) == (60, 100, 100)
+
+
+def test_hsl_to_rgb_part_15():
+    assert hsl_to_rgb(120, 100, 0) == (0, 0, 0)
+    assert hsl_to_rgb(120, 100, 10) == (0, 51, 0)
+    assert hsl_to_rgb(120, 100, 20) == (0, 102, 0)
+    assert hsl_to_rgb(120, 100, 30) == (0, 153, 0)
+    assert hsl_to_rgb(120, 100, 40) == (0, 204, 0)
+    assert hsl_to_rgb(120, 100, 50) == (0, 255, 0)
+    assert hsl_to_rgb(120, 100, 60) == (51, 255, 51)
+    assert hsl_to_rgb(120, 100, 70) == (102, 255, 102)
+    assert hsl_to_rgb(120, 100, 80) == (153, 255, 153)
+    assert hsl_to_rgb(120, 100, 90) == (204, 255, 204)
+    assert hsl_to_rgb(120, 100, 100) == (255, 255, 255)
+
+
+def test_rgb_to_hsl_part_15():
+    # assert rgb_to_hsl(0, 0, 0) == (120, 100, 0)
+    assert rgb_to_hsl(0, 51, 0) == (120, 100, 10)
+    assert rgb_to_hsl(0, 102, 0) == (120, 100, 20)
+    assert rgb_to_hsl(0, 153, 0) == (120, 100, 30)
+    assert rgb_to_hsl(0, 204, 0) == (120, 100, 40)
+    assert rgb_to_hsl(0, 255, 0) == (120, 100, 50)
+    assert rgb_to_hsl(51, 255, 51) == (120, 100, 60)
+    assert rgb_to_hsl(102, 255, 102) == (120, 100, 70)
+    assert rgb_to_hsl(153, 255, 153) == (120, 100, 80)
+    assert rgb_to_hsl(204, 255, 204) == (120, 100, 90)
+    # assert rgb_to_hsl(255, 255, 255) == (120, 100, 100)
+
+
+def test_hsl_to_rgb_part_16():
+    assert hsl_to_rgb(180, 100, 0) == (0, 0, 0)
+    assert hsl_to_rgb(180, 100, 10) == (0, 51, 51)
+    assert hsl_to_rgb(180, 100, 20) == (0, 102, 102)
+    assert hsl_to_rgb(180, 100, 30) == (0, 153, 153)
+    assert hsl_to_rgb(180, 100, 40) == (0, 204, 204)
+    assert hsl_to_rgb(180, 100, 50) == (0, 255, 255)
+    assert hsl_to_rgb(180, 100, 60) == (51, 255, 255)
+    assert hsl_to_rgb(180, 100, 70) == (102, 255, 255)
+    assert hsl_to_rgb(180, 100, 80) == (153, 255, 255)
+    assert hsl_to_rgb(180, 100, 90) == (204, 255, 255)
+    assert hsl_to_rgb(180, 100, 100) == (255, 255, 255)
+
+
+def test_rgb_to_hsl_part_16():
+    # assert rgb_to_hsl(0, 0, 0) == (180, 100, 0)
+    assert rgb_to_hsl(0, 51, 51) == (180, 100, 10)
+    assert rgb_to_hsl(0, 102, 102) == (180, 100, 20)
+    assert rgb_to_hsl(0, 153, 153) == (180, 100, 30)
+    assert rgb_to_hsl(0, 204, 204) == (180, 100, 40)
+    assert rgb_to_hsl(0, 255, 255) == (180, 100, 50)
+    assert rgb_to_hsl(51, 255, 255) == (180, 100, 60)
+    assert rgb_to_hsl(102, 255, 255) == (180, 100, 70)
+    assert rgb_to_hsl(153, 255, 255) == (180, 100, 80)
+    assert rgb_to_hsl(204, 255, 255) == (180, 100, 90)
+    # assert rgb_to_hsl(255, 255, 255) == (180, 100, 100)
+
+
+def test_hsl_to_rgb_part_17():
+    assert hsl_to_rgb(240, 100, 0) == (0, 0, 0)
+    assert hsl_to_rgb(240, 100, 10) == (0, 0, 51)
+    assert hsl_to_rgb(240, 100, 20) == (0, 0, 102)
+    assert hsl_to_rgb(240, 100, 30) == (0, 0, 153)
+    assert hsl_to_rgb(240, 100, 40) == (0, 0, 204)
+    assert hsl_to_rgb(240, 100, 50) == (0, 0, 255)
+    assert hsl_to_rgb(240, 100, 60) == (51, 51, 255)
+    assert hsl_to_rgb(240, 100, 70) == (102, 102, 255)
+    assert hsl_to_rgb(240, 100, 80) == (153, 153, 255)
+    assert hsl_to_rgb(240, 100, 90) == (204, 204, 255)
+    assert hsl_to_rgb(240, 100, 100) == (255, 255, 255)
+
+
+def test_rgb_to_hsl_part_17():
+    # assert rgb_to_hsl(0, 0, 0) == (240, 100, 0)
+    assert rgb_to_hsl(0, 0, 51) == (240, 100, 10)
+    assert rgb_to_hsl(0, 0, 102) == (240, 100, 20)
+    assert rgb_to_hsl(0, 0, 153) == (240, 100, 30)
+    assert rgb_to_hsl(0, 0, 204) == (240, 100, 40)
+    assert rgb_to_hsl(0, 0, 255) == (240, 100, 50)
+    assert rgb_to_hsl(51, 51, 255) == (240, 100, 60)
+    assert rgb_to_hsl(102, 102, 255) == (240, 100, 70)
+    assert rgb_to_hsl(153, 153, 255) == (240, 100, 80)
+    assert rgb_to_hsl(204, 204, 255) == (240, 100, 90)
+    # assert rgb_to_hsl(255, 255, 255) == (240, 100, 100)
+
+
+def test_hsl_to_rgb_part_18():
+    assert hsl_to_rgb(300, 100, 0) == (0, 0, 0)
+    assert hsl_to_rgb(300, 100, 10) == (51, 0, 51)
+    assert hsl_to_rgb(300, 100, 20) == (102, 0, 102)
+    assert hsl_to_rgb(300, 100, 30) == (153, 0, 153)
+    assert hsl_to_rgb(300, 100, 40) == (204, 0, 204)
+    assert hsl_to_rgb(300, 100, 50) == (255, 0, 255)
+    assert hsl_to_rgb(300, 100, 60) == (255, 51, 255)
+    assert hsl_to_rgb(300, 100, 70) == (255, 102, 255)
+    assert hsl_to_rgb(300, 100, 80) == (255, 153, 255)
+    assert hsl_to_rgb(300, 100, 90) == (255, 204, 255)
+    assert hsl_to_rgb(300, 100, 100) == (255, 255, 255)
+
+
+def test_rgb_to_hsl_part_18():
+    # assert rgb_to_hsl(0, 0, 0) == (300, 100, 0)
+    assert rgb_to_hsl(51, 0, 51) == (300, 100, 10)
+    assert rgb_to_hsl(102, 0, 102) == (300, 100, 20)
+    assert rgb_to_hsl(153, 0, 153) == (300, 100, 30)
+    assert rgb_to_hsl(204, 0, 204) == (300, 100, 40)
+    assert rgb_to_hsl(255, 0, 255) == (300, 100, 50)
+    assert rgb_to_hsl(255, 51, 255) == (300, 100, 60)
+    assert rgb_to_hsl(255, 102, 255) == (300, 100, 70)
+    assert rgb_to_hsl(255, 153, 255) == (300, 100, 80)
+    assert rgb_to_hsl(255, 204, 255) == (300, 100, 90)
+    # assert rgb_to_hsl(255, 255, 255) == (300, 100, 100)
diff --git a/pygal/test/test_style.py b/pygal/test/test_style.py
index 5048aee..73f0650 100644
--- a/pygal/test/test_style.py
+++ b/pygal/test/test_style.py
@@ -16,7 +16,7 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with pygal. If not, see <http://www.gnu.org/licenses/>.
-from pygal.style import Style, darken, lighten
+from pygal.style import Style
 
 
 def test_colors():
@@ -102,21 +102,3 @@ def test_colors():
   fill: rgb(12, 231, 3);
 }
 '''
-
-
-def test_darken():
-    assert darken('#800', 20) == '#220000'
-    assert darken('#ffffff', 10) == '#e6e6e6'
-    assert darken('#f3148a', 25) == '#810747'
-    assert darken('#121212', 1) == '#0f0f0f'
-    assert darken('#999999', 100) == '#000000'
-    assert darken('#1479ac', 8) == '#105f87'
-
-
-def test_lighten():
-    assert lighten('#800', 20) == '#ee0000'
-    assert lighten('#ffffff', 10) == '#ffffff'
-    assert lighten('#f3148a', 25) == '#f98dc6'
-    assert lighten('#121212', 1) == '#151515'
-    assert lighten('#999999', 100) == '#ffffff'
-    assert lighten('#1479ac', 8) == '#1893d1'
diff --git a/pygal/test/test_util.py b/pygal/test/test_util.py
index c301066..4051253 100644
--- a/pygal/test/test_util.py
+++ b/pygal/test/test_util.py
@@ -19,7 +19,7 @@
 from pygal._compat import u
 from pygal.util import (
     round_to_int, round_to_float, _swap_curly, template, humanize,
-    is_major, truncate, minify_css, rgb_to_hsl, hsl_to_rgb)
+    is_major, truncate, minify_css)
 from pytest import raises
 
 
diff --git a/pygal/util.py b/pygal/util.py
index 02ec6a2..0f82fa6 100644
--- a/pygal/util.py
+++ b/pygal/util.py
@@ -382,54 +382,3 @@ def split_title(title, width, title_fs):
         title = title[i:].strip()
     titles.append(title)
     return titles
-
-
-def rgb_to_hsl(r, g, b):
-    r /= 255
-    g /= 255
-    b /= 255
-    max_ = max((r, g, b))
-    min_ = min((r, g, b))
-    d = max_ - min_
-
-    if not d:
-        h = 0
-    elif r is max_:
-        h = 60 * (g - b) / d
-    elif g is max_:
-        h = 60 * (b - r) / d + 120
-    else:
-        h = 60 * (r - g) / d + 240
-
-    l = .5 * (max_ + min_)
-    if not d:
-        s = 0
-    elif l < 0.5:
-        s = .5 * d / l
-    else:
-        s = .5 * d / (1 - l)
-
-    return h % 360, s * 100, l * 100
-
-
-def hsl_to_rgb(h, s, l):
-    h /= 360
-    s /= 100
-    l /= 100
-
-    m2 = l * (s + 1) if l <= .5 else l + s - l * s
-    m1 = 2 * l - m2
-
-    def h_to_rgb(h):
-        h = h % 1
-        if 6 * h < 1:
-            return m1 + 6 * h * (m2 - m1)
-        if 2 * h < 1:
-            return m2
-        if 3 * h < 2:
-            return m1 + 6 * (2 / 3 - h) * (m2 - m1)
-        return m1
-    r, g, b = map(lambda x: round(x * 255),
-                  map(h_to_rgb, (h + 1 / 3, h, h - 1 / 3)))
-
-    return r, g, b