def test_percentage_difference_50pc(self):
"""Percentage difference between values where one is 50% of the other"""
value_1 = 2000
value_2 = 4000
diff_1 = calc_percentage_difference(value_2, value_1)
diff_2 = calc_percentage_difference(value_1, value_2)
self.assertEquals(diff_1, diff_2)
self.assertAlmostEquals(0.666, diff_1, 2)
def test_percentage_difference(self):
"""Percentage difference between two values that are almost equal"""
value_1 = 3999.9999
value_2 = 4000
diff_1 = calc_percentage_difference(value_2, value_1)
diff_2 = calc_percentage_difference(value_1, value_2)
self.assertEquals(diff_1, diff_2)
self.assertAlmostEquals(0.00000, diff_1, 2)
def test_percentage_difference_99pc(self):
"""Percentage difference between a very small value and a relatively
large value"""
value_1 = 0.0000000001
value_2 = 2**32
diff_1 = calc_percentage_difference(value_2, value_1)
diff_2 = calc_percentage_difference(value_1, value_2)
self.assertEquals(diff_1, diff_2)
self.assertAlmostEquals(1.999999, diff_1, 2)
