Question

I just wrote Python code to solve this problem:

Write a generator that will return a sequence of month names. Thus

gen = next_month('October')

creates a generator that generates the strings 'November', 'December', 'January' and so on.
If the caller supplies an illegal month name, your function should raise a ValueError exception with text explaining the problem.

Here is my code:

month_names = ['January', 'February', 'March', 'April', 'May', 'June',
'July', 'August', 'September', 'October', 'November', 'December']

def next_month(name: str) -> str:
"Return a stream of the following months"
global month_names
while True:
try:
yield name
  
except StopIteration:
break

When I run this unit test below, I fail because it is not accepting lowercase 'december'. How can I fix this?

def test_months():
gen = next_month('October')
lst = [next(gen) for i in range(15)]
assert(lst == ['November', 'December', 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December', 'January'])
  
gen = next_month('december')
assert next(gen) == 'January'
  
test_months()

Answer 1

CODE:

To fix that i have defined a new look up list where every element is conerted to lower case and compared.

Text:

month_names = ['January', 'February', 'March', 'April', 'May', 'June',

'July', 'August', 'September', 'October', 'November', 'December']

def next_month(name: str) -> str:

    "Return a stream of the following months"

    month_names_lookup = [mname.lower() for mname in month_names]

    index = month_names_lookup.index(name.lower())

    while True:

        try:

            index += 1

            yield month_names[index % len(month_names)]

        except StopIteration:

            break

    

def test_months():

    gen = next_month('October')

    lst = [next(gen) for i in range(15)]

    assert(lst == ['November', 'December', 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December', 'January'])

    

    gen = next_month('december')

    assert next(gen) == 'January'

  

test_months()

For Handling Value error: