tools/auto_bisect/math_utils_test.py

   1 # Copyright 2014 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import math
   6 import unittest
   7
   8 import math_utils
   9
  10
  11 class MathUtilsTest(unittest.TestCase):
  12   """Tests for mathematical utility functions."""
  13
  14   def testTruncatedMeanRaisesError(self):
  15     """TruncatedMean should raise an error when passed an empty list."""
  16     with self.assertRaises(TypeError):
  17       math_utils.TruncatedMean([], 0)
  18
  19   def testMeanSingleNum(self):
  20     """Tests the Mean function with a single number."""
  21     self.assertEqual(3.0, math_utils.Mean([3]))
  22
  23   def testMeanShortList(self):
  24     """Tests the Mean function with a short list."""
  25     self.assertEqual(0.5, math_utils.Mean([-3, 0, 1, 4]))
  26
  27   def testMeanCompareAlternateImplementation(self):
  28     """Tests Mean by comparing against an alternate implementation."""
  29     def AlternateMeanFunction(values):
  30       """Simple arithmetic mean function."""
  31       return sum(values) / float(len(values))
  32     test_values_lists = [[1], [5, 6.5, 1.2, 3], [-3, 0, 1, 4],
  33                          [-3, -1, 0.12, 0.752, 3.33, 8, 16, 32, 439]]
  34     for values in test_values_lists:
  35       self.assertEqual(
  36           AlternateMeanFunction(values),
  37           math_utils.Mean(values))
  38
  39   def testRelativeChange(self):
  40     """Tests the common cases for calculating relative change."""
  41     # The change is relative to the first value, regardless of which is bigger.
  42     self.assertEqual(0.5, math_utils.RelativeChange(1.0, 1.5))
  43     self.assertEqual(0.5, math_utils.RelativeChange(2.0, 1.0))
  44
  45   def testRelativeChangeFromZero(self):
  46     """Tests what happens when relative change from zero is calculated."""
  47     # If the first number is zero, then the result is not a number.
  48     self.assertEqual(0, math_utils.RelativeChange(0, 0))
  49     self.assertTrue(
  50         math.isnan(math_utils.RelativeChange(0, 1)))
  51     self.assertTrue(
  52         math.isnan(math_utils.RelativeChange(0, -1)))
  53
  54   def testRelativeChangeWithNegatives(self):
  55     """Tests that relative change given is always positive."""
  56     self.assertEqual(3.0, math_utils.RelativeChange(-1, 2))
  57     self.assertEqual(3.0, math_utils.RelativeChange(1, -2))
  58     self.assertEqual(1.0, math_utils.RelativeChange(-1, -2))
  59
  60
  61 if __name__ == '__main__':
  62   unittest.main()