public void returns_undefined_with_single_negative_input()
{
//arrange
var inputData = new[] { -1.0 };
//act
var semiDeviation = inputData.SemiDeviation();
//assert
Assert.AreEqual(double.NaN, semiDeviation);
}
public void only_uses_data_points_below_the_mean_of_all_data()
{
//arrange
var inputData = new[] { 1.0, 2.0, 3.0, 4.0 };
var mean = inputData.Mean();
var expectedSemiDeviation = inputData.Where(x => x < mean).StandardDeviation();
//act
var semiDeviation = inputData.SemiDeviation();
//assert
Assert.AreEqual(expectedSemiDeviation, semiDeviation);
}
public void handles_negative_values()
{
//arrange
var inputData = new[] { -1.0, 2.0, 3.0, 4.0 };
var mean = inputData.Mean();
var expectedSemiDeviation = inputData.Where(x => x < mean).StandardDeviation();
//act
var semiDeviation = inputData.SemiDeviation();
//assert
Assert.AreEqual(expectedSemiDeviation, semiDeviation);
}
