def test_std1():
obs = std([0.0, 2.0])
exp = 1.0
assert obs == exp
def test_std5():
# Here, we have more than two values, but all of the values are the same.
obs = std([1.0, 1.0, 1.0])
exp = 0.0
assert obs == exp
def test_std3():
# Test a real case where the answer is not one.
obs = std([0.0, 4.0])
exp = 2.0
assert obs == exp
def test_std4():
# The first value is not zero.
obs = std([1.0, 3.0])
exp = 1.0
assert obs == exp
def test_std2():
# Test the fiducial case when we pass in an empty list.
obs = std([])
exp = 0.0
assert obs == exp