Please provide code for a unit test program to test the following functions:

def addition(x, y):

return x + y

def subtraction(x, y):

return x - y

def multiplication(x, y):

return x * y

def division(x, y):

return x / y

 

For each function, should test:

1. When given two positive numbers, whether the function returns correct value
2. When given negative numbers, whether the function returns correct value
3. When given one positive number and one negative number , whether the function returns correct value