functions: test_functions_w_positional_arguments¶

test_functions_w_positional_arguments ¶

I can define a function to take in more than one input, For instance if I am writing a function to perform operations on 2 numbers as I do in how to make a calculator , the function has to be able to take the 2 numbers it performs operations on. I add a new test to test_functions.py

def test_functions_w_positional_arguments(self):
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_first_name', 'my_last_name'
        ),
        ('my_first_name', 'my_last_name')
    )

the terminal shows AttributeError

green: make it pass¶

I add the solution I know works from test_passthrough_functions functions.py
```
def passthrough_w_positional_arguments(argument):
    return argument
```
the terminal shows TypeError
I make the signature of passthrough_w_positional_arguments to take in more than one argument
```
def passthrough_w_positional_arguments(
    argument, second_argument
):
    return argument
```
the terminal shows AssertionError

I make passthrough_w_positional_arguments return the 2 arguments it receives

def passthrough_w_positional_arguments(
    argument, second_argument
):
    return argument, second_argument

the terminal shows passing tests

refactor: make it better¶

How can I make this better?

I called the first argument argument and the second argument second_argument. Technically, both arguments are input data, so I need a better name that is more descriptive

I make the signature of passthrough_w_positional_arguments to use more descriptive names

def passthrough_w_positional_arguments(
    first_argument, second_argument
):
    return first_argument, second_argument

I still have passing tests

I add another test to ensure that passthrough_w_positional_arguments outputs data in the order given

def test_functions_w_positional_arguments(self):
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_first_name', 'my_last_name'
        ),
        ('my_first_name', 'my_last_name')
    )
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_last_name', 'my_first_name'
        ),
        ('my_first_name', 'my_last_name')
    )

the terminal shows AssertionError

I make the test so it has the right output

def test_functions_w_positional_arguments(self):
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_first_name', 'my_last_name'
        ),
        ('my_first_name', 'my_last_name')
    )
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_last_name', 'my_first_name'
        ),
        ('my_last_name', 'my_first_name')
    )

the terminal shows passing tests

the function currently takes in 2 positional arguments. There are scenarios where a function needs to take in more arguments, like when I do not know the number of positional arguments that will be passed to the function

I add tests for cases where the number of positional arguments received is not known test_functions_w_positional_arguments

def test_functions_w_positional_arguments(self):
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_first_name', 'my_last_name'
        ),
        ('my_first_name', 'my_last_name')
    )
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            'my_last_name', 'my_first_name'
        ),
        ('my_last_name', 'my_first_name')
    )
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            0, 1, 2, 3
        ),
        (0, 1, 2, 3)
    )
    self.assertEqual(
        functions.passthrough_w_positional_arguments(
            bool, int, float, str, tuple, list, set, dict
        ),
        (bool, int, float, str, tuple, list, set, dict)
    )

the terminal shows TypeError because 2 positional arguments were expected by the function but 4 were given

in Python I can represent multiple arguments using a starred expression see arbitrary argument lists, so I make the signature of functions_w_positional_arguments with a starred expression to alow it take in any number of arguments
```
def passthrough_w_positional_arguments(*arguments):
    return arguments
```
the terminal shows passing tests

review ¶

From the tests I know

I can use *name to represent any number of positional arguments
that positional arguments are represented as tuples with parentheses - ()
that passthrough functions return what they receive as input
that singleton functions return the same thing every time they are called
functions are defined using the def keyword
functions return None by default

Would you like to test_functions_with keyword arguments?

functions: tests and solutions

functions: test_functions_w_positional_arguments¶

test_functions_w_positional_arguments¶

green: make it pass¶

refactor: make it better¶

review¶

test_functions_w_positional_arguments ¶

review ¶