sweetberry: calculate statistics for sweetberry readings

This CL provides the tool to calculate statistics for sweetberry
readings and present them in a clear & easy to read format. It
also provides the flag to store raw data and statistics
summary, should the need arise.
There are also some code cleanup for powerlog.py.

BRANCH=None
BUG=b:35578707
TEST=./powerlog.py -b xxx.board -c xxx.scenario --print_stats \
--save_stats --save_raw_data
python -m unittest -v stats_manager_unittest

Change-Id: I4aa732756fe6512f37acfcb59b11d950101887d7
Signed-off-by: Mengqi Guo <mqg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/667241
Reviewed-by: Nick Sanders <nsanders@chromium.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/extra/usb_power/stats_manager_unittest.py b/extra/usb_power/stats_manager_unittest.py
new file mode 100644
index 0000000000..9b86b15ad4
--- /dev/null
+++ b/extra/usb_power/stats_manager_unittest.py
@@ -0,0 +1,87 @@
+# Copyright 2017 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Unit tests for StatsManager."""
+
+from __future__ import print_function
+import os
+import shutil
+import tempfile
+import unittest
+
+from stats_manager import StatsManager
+
+class TestStatsManager(unittest.TestCase):
+  """Test to verify StatsManager methods work as expected.
+
+  StatsManager should collect raw data, calculate their statistics, and save
+  them in expected format.
+  """
+
+  def setUp(self):
+    """Set up data and create a temporary directory to save data and stats."""
+    self.tempdir = tempfile.mkdtemp()
+    self.data = StatsManager()
+    self.data.AddValue('A', 99999.5)
+    self.data.AddValue('A', 100000.5)
+    self.data.AddValue('A', 'ERROR')
+    self.data.AddValue('B', 1.5)
+    self.data.AddValue('B', 2.5)
+    self.data.AddValue('B', 3.5)
+    self.data.CalculateStats()
+
+  def tearDown(self):
+    """Delete the temporary directory and its content."""
+    shutil.rmtree(self.tempdir)
+
+  def test_GetRawData(self):
+    raw_data = self.data.GetRawData()
+    self.assertListEqual([99999.5, 100000.5], raw_data['A'])
+    self.assertListEqual([1.5, 2.5, 3.5], raw_data['B'])
+
+  def test_GetSummary(self):
+    summary = self.data.GetSummary()
+    self.assertEqual(2, summary['A']['count'])
+    self.assertAlmostEqual(100000.5, summary['A']['max'])
+    self.assertAlmostEqual(99999.5, summary['A']['min'])
+    self.assertAlmostEqual(0.5, summary['A']['stddev'])
+    self.assertAlmostEqual(100000.0, summary['A']['mean'])
+    self.assertEqual(3, summary['B']['count'])
+    self.assertAlmostEqual(3.5, summary['B']['max'])
+    self.assertAlmostEqual(1.5, summary['B']['min'])
+    self.assertAlmostEqual(0.81649658092773, summary['B']['stddev'])
+    self.assertAlmostEqual(2.5, summary['B']['mean'])
+
+  def test_SaveRawData(self):
+    dirname = 'unittest_raw_data'
+    self.data.SaveRawData(self.tempdir, dirname)
+    dirname = os.path.join(self.tempdir, dirname)
+    fileA = os.path.join(dirname, 'A.txt')
+    fileB = os.path.join(dirname, 'B.txt')
+    with open(fileA, 'r') as fA:
+      self.assertEqual('99999.50', fA.readline().strip())
+      self.assertEqual('100000.50', fA.readline().strip())
+    with open(fileB, 'r') as fB:
+      self.assertEqual('1.50', fB.readline().strip())
+      self.assertEqual('2.50', fB.readline().strip())
+      self.assertEqual('3.50', fB.readline().strip())
+
+  def test_SaveSummary(self):
+    fname = 'unittest_summary.txt'
+    self.data.SaveSummary(self.tempdir, fname)
+    fname = os.path.join(self.tempdir, fname)
+    with open(fname, 'r') as f:
+      self.assertEqual(
+          '@@   NAME  COUNT       MEAN  STDDEV        MAX       MIN\n',
+          f.readline())
+      self.assertEqual(
+          '@@      A      2  100000.00    0.50  100000.50  99999.50\n',
+          f.readline())
+      self.assertEqual(
+          '@@      B      3       2.50    0.82       3.50      1.50\n',
+          f.readline())
+
+
+if __name__ == '__main__':
+  unittest.main()