Testing mean#

Suppose you’re writing a function that computes the arithmetic mean (i.e., average, i.e., sum and divide by the length) of a list of numbers. You’d like to test your function. Which examples should you run?

Here is a sample you can run on IDLE:

>>> from example import mean

Please don't edit the line above---we need it for the code to work. Write as many doctests as you like for the function `mean` below.

Here's one to start you off:

>>> mean([1])
1.0

Consider using the following definitions of mean:

# Definition of mean that only returns the first element
def mean(l):
    return l[0]

# Definition of mean that only returns the last element
def mean(l):
    return l[-1]

# The correct definition
def mean(l):
    return sum(l) / len(l)

# Returns the median instead of the mean
def mean(l):
    l.sort()
    return float(l[len(l)//2])

Here are a few function calls you can use to test your function:

>>> mean([1,2,3])
2.0
>>> mean([3,1,2])
2.0
>>> mean([2,1])
1.5
>>> mean([1,2])
1.5

These tests ensure that the following events do not happen:

The function does not return the first element of the list
The function does not return the last element of the list
The function does not return the median of the list

It is important that all possible cases are concidered when making a function!