class TestSnapshot(TestCase):
def setUp(self):
self.values = [5, 1, 2, 3, 4]
self.snap = Snapshot(self.values)
def test_small_percentile_is_first_element(self):
self.assertEqual(self.snap.get_value(0.01), 1)
def test_big_percentile_is_last_element(self):
self.assertEqual(self.snap.get_value(1.0), 5)
def test_disallows_negative_percentile(self):
self.assertRaises(TypeError, self.snap.get_value, (-0.42,))
def test_disallows_percentile_larger_then_one(self):
self.assertRaises(TypeError, self.snap.get_value, (1.1,))
def test_42th_percentile(self):
self.assertEqual(self.snap.get_value(0.42), 2.52)
def test_75th_percentile(self):
self.assertEqual(self.snap.get_value(0.75), 4.5)
def test_95th_percentile(self):
self.assertEqual(self.snap.get_value(0.95), 5.0)
def test_98th_percentile(self):
self.assertEqual(self.snap.get_value(0.98), 5.0)
def test_99th_percentile(self):
self.assertEqual(self.snap.get_value(0.99), 5.0)
def test_999th_percentile(self):
self.assertEqual(self.snap.get_value(0.999), 5.0)
def test_calculates_the_mean_value(self):
self.assertEqual(self.snap.mean, 3.0)
def test_calculates_mean_of_zero_for_empty_snapshot(self):
snap = WeightedSnapshot([])
self.assertEqual(snap.mean, 0)
def test_calculates_the_stddev(self):
self.assertAlmostEqual(self.snap.stddev, 1.5811, places=4)
def test_calculates_a_stddev_of_zero_for_empty_snapshot(self):
snap = WeightedSnapshot([])
self.assertEqual(snap.stddev, 0)
def test_calculates_a_stddev_of_zero_for_snapshot_of_one_item(self):
snap = WeightedSnapshot([(1, 1)])
self.assertEqual(snap.stddev, 0)
def setUp(self):
self.values = [5, 1, 2, 3, 4]
self.snap = Snapshot(self.values)