How to test a function call using Python and unittest library

Question

I just had a question on how you write a test for the following function? Here is my test for the part that is covered, but I am not sure how I would change the test to cover the print statement and calling the get_employee_name function again. Any help would be appreciated!

Here is my code to test the covered part:

DATA = {
"employee_name": "Brian Weber",
"minutes": 120,
"task_name": "Surfing",
"notes": "These are my notes.",
"date": "2016-12-25"
}


class WorkLogTests(unittest.TestCase):
    def test_get_employee_name(self):
        with mock.patch('builtins.input',
            return_value=DATA["employee_name"]):
            assert worklog.get_employee_name() == DATA["employee_name"]

...really?! Well, under what circumstances do you think those lines would be exercised? — jonrsharpe, Dec 13 '16 at 19:46
Well if there was no input then that part of the code would run. Sorry new to testing here. — Brian, Dec 13 '16 at 19:48
No, I'm not saying that. If you want to cover those lines, you need to write another test with *different* input data. This will demonstrate why your current implementation is broken. Also, note that recursion isn't the best way to do this; see e.g. http://stackoverflow.com/q/23294658/3001761. — jonrsharpe, Dec 13 '16 at 19:49
Ok so would I use side_effect attribute to use different input data? I'm just confused on the syntax on how I would write the test. — Brian, Dec 13 '16 at 19:51
I ended up using a while loop with continue if the user didn't enter anything. I'll post the answer — Brian, Dec 13 '16 at 19:59
But that doesn't tell you how to *test* it in cases where the first input isn't valid - the test shouldn't care whether it's recursive or iterative. — jonrsharpe, Dec 13 '16 at 20:00
@jonrsharpe what about this? with mock.patch('builtins.input', side_effect=["", "Name"], return_value=DATA["employee_name"]): assert worklog.get_employee_name() == DATA["employee_name"] — Brian, Dec 13 '16 at 20:06

score 0 · Accepted Answer · edited Jul 20 '20 at 13:43

The first problem I had was using recursion if the user didn't enter anything. So I refactored my code to use a while loop using continue if there was no user input. Here is the new code and the test covering all lines:

def get_employee_name():
    """Prompt the employee for their name."""
    while True:
        employee_name = input("Enter employee name: ")
        if len(employee_name) == 0:
            print("\nYou must enter your name!\n")
            continue
        else:
            return employee_name

def test_get_employee_name(self):
    with mock.patch('builtins.input', side_effect=["", "Brian Weber"],
        return_value=DATA["employee_name"]):
        assert worklog.get_employee_name() == DATA["employee_name"]

How to test a function call using Python and unittest library

1 Answers1