telephone with separation

The text function in the telephone project was written in test_telephone.py. I want to move it to telephone.py in the src folder so that I can keep the tests and solution separate.

preview

I have these tests by the end of the chapter

open the project

  • I name this project telephone

  • I open a terminal

  • I use uv to make a directory for the project and initialize it

    uv init telephone

    the terminal shows

    Initialized project `telephone`
at `.../pumping_python/telephone`

    then goes back to the command line.

  • I change directory to the project

    cd telephone

    the terminal shows I am in the telephone folder

    .../pumping_python/telephone

  • I make a directory for the tests

    mkdir tests

    the terminal goes back to the command line.

  • I make the tests directory a Python package

    Danger

    use 2 underscores (__) before and after init for __init__.py not _init_.py

    touch tests/__init__.py

    New-Item tests/__init__.py

    the terminal goes back to the command line.

  • I use the mv program to change the name of main.py to test_telephone.py and move it to the tests folder

    mv main.py tests/test_telephone.py

    Move-Item main.py tests/test_telephone.py

    the terminal goes back to the command line.

  • I open test_telephone.py

  • I delete all the text then add the first failing test to test_telephone.py

    1def test_failure():
2    assert False is True

  • I go back to the terminal to make a requirements file for the Python packages I need

    echo "pytest" > requirements.txt

    the terminal goes back to the command line.

  • I add pytest-watcher to the requirements file

    echo "pytest-watcher" >> requirements.txt

    the terminal goes back to the command line.

  • I use uv to install pytest-watcher with the requirements file

    uv add --requirement requirements.txt

    the terminal shows that it installed pytest-watcher and its dependencies.

  • I add the new files and folders to git for tracking

    git add .

    the terminal goes back to the command line.

  • I add a git commit message

    git commit --all --message 'setup project'

    the terminal shows

    [main (root-commit) a0b12c3] setup project
 8 files changed, X insertions(+)
 create mode 100644 .gitignore
 create mode 100644 .python-version
 create mode 100644 README.md
 create mode 100644 pyproject.toml
 create mode 100644 requirements.txt
 create mode 100644 tests/__init__.py
 create mode 100644 tests/test_telephone.py
 create mode 100644 uv.lock

    then goes back to the command line.

  • I use pytest-watcher to run the tests automatically

    uv run pytest-watcher . --now

    the terminal is my friend, and shows AssertionError

    ======================== FAILURES ========================
______________________ test_failure ______________________

    def test_failure():
>       assert False is True
E       assert False is True

test_telephone.py:2: AssertionError
================ short test summary info =================
FAILED test_telephone.py::test_failure - assert False is True
=================== 1 failed in X.YZs ====================

    because True is NOT False.

    if the terminal does not show the same error, then check

    • if your tests/__init__.py has two underscores (__) before and after init for __init__.py not _init_.py

    • if you ran echo "pytest-watcher" >> requirements.txt, to add pytest-watcher to the requirements file

    and try uv run pytest-watcher . --now again

  • I add AssertionError to the list of Exceptions seen in test_telephone.py

    1def test_failure():
2    assert False is True
3
4
5# Exceptions seen
6# AssertionError

  • I change True to False in the assertion

    1def test_failure():
2    # assert False is True
3    assert False is False
4
5
6# Exceptions seen
7# AssertionError

    the test passes.

separate and equal

So far all functions I have written have been in the same file as the tests, some are even in the same function as the assertions of the tests.

In earlier tests I found it better to keep functions outside of functions so that anything could call them from outside.

I can also place them in other modules then use the import statement to bring in the function so I can test it. This helps me keep tests and solutions separate. It also means I can send tests only, solutions only or both.

RED: make it fail

  • I go back to the terminal where the tests are running

  • I change the assertion to call the text function of the telephone module in the src folder

     1def text(the_input):
 2    return f'I got: {the_input}'
 3
 4
 5def test_passing_none():
 6    # assert text(None) == 'I got: None'
 7    reality = src.telephone.text(None)
 8    my_expectation = 'I got: None'
 9    assert reality == my_expectation
10
11
12def test_passing_booleans():

    the terminal is my friend, and shows NameError

    NameError: name 'src' is not defined

    because there is nothing with that name in test_telephone.py.

GREEN: make it pass

  • I add an import statement at the top of test_telephone.py

    1import src
2
3
4def text(the_input):

    the terminal is my friend, and shows ModuleNotFoundError

    E   ModuleNotFoundError: No module named 'src'

    because there is nothing named src in the project.

  • I add ModuleNotFoundError to the list of Exceptions seen

    73# Exceptions seen
74# AssertionError
75# NameError
76# TypeError
77# ModuleNotFoundError

  • I go to the other terminal

  • I use mkdir to make a folder named src

    mkdir src

    the terminal goes back to the command line.

  • I go back to the terminal where the tests are running

  • I use ctrl/command+s (Windows & Linux/MacOS) in test_telephone.py to run the test again, and the terminal shows AttributeError

    AttributeError: module 'src' has no attribute 'telephone'

    because there is nothing named telephone in the src folder.

  • I add AttributeError to the list of Exceptions seen

    73# Exceptions seen
74# AssertionError
75# NameError
76# TypeError
77# ModuleNotFoundError
78# AttributeError

  • I change the import statement to make it import telephone.py from the src folder

    1# import src
2import src.telephone
3
4
5def text(the_input):

    the terminal is my friend, and shows ModuleNotFoundError

    E   ModuleNotFoundError: No module named 'src.telephone'

    because Python cannot find telephone.py in the src folder since I have not made it yet.

  • I go to the other terminal

  • I use touch to make telephone.py in the src folder

    touch src/telephone.py

    New-Item src/telephone.py

    the terminal goes back to the command line.

  • I go back to the terminal where the tests are running and it shows AttributeError

    AttributeError: module 'src.telephone' has no attribute 'text'

    because telephone.py in the src folder does not have anything named text inside it.

  • I open telephone.py from the src folder

  • I add a copy of the text function to telephone.py

    1def text(the_input):
2    return f'I got: {the_input}'

    the test passes because

    • when import src.telephone runs, Python brings in an object for the telephone.py file from the src folder so I can use it in test_telephone.py as src.telephone

    • when src.telephone.text(None) runs, Python calls the text function from the object it imported for the telephone.py file from the src folder (src.telephone)

    I think of src.telephone.text like an address

    src.telephone.text
src
└── telephone.py
    └── def text(the_input):
        └── return f'I got: {the input}'

REFACTOR: make it better

  • I remove the commented lines from test_telephone.py

     1import src.telephone
 2
 3
 4def text(the_input):
 5    return f'I got: {the_input}'
 6
 7
 8def test_passing_none():
 9    reality = src.telephone.text(None)
10    my_expectation = 'I got: None'
11    assert reality == my_expectation
12
13
14def test_passing_booleans():

  • I change the call in the first assertion of test_passing_booleans to src.telephone.text

    14def test_passing_booleans():
15    # assert text(False) == 'I got: False'
16    reality = src.telephone.text(False)
17    my_expectation = 'I got: False'
18    assert reality == my_expectation
19    assert text(True) == 'I got: True'
20
21
22def test_passing_an_integer():

    the test is still green because when src.telephone.text is called, Python follows this path

    src.telephone.text
src
└── telephone.py
    └── def text(the_input):
        └── return f'I got: {the input}'

    then uses the string representation of the object in the curly braces { }

    text(None)
    text(the_input)
        the_input = None
        return f'I got: {the_input}'
        return  'I got:  None      '

  • I make the same change for the next assertion

    14def test_passing_booleans():
15    # assert text(False) == 'I got: False'
16    reality = src.telephone.text(False)
17    my_expectation = 'I got: False'
18    assert reality == my_expectation
19    # assert text(True) == 'I got: True'
20    reality = src.telephone.text(True)
21    my_expectation = 'I got: True'
22    assert reality == my_expectation
23
24
25def test_passing_an_integer():

    still green.

  • I remove the commented lines from test_passing_booleans

    14def test_passing_booleans():
15    reality = src.telephone.text(False)
16    my_expectation = 'I got: False'
17    assert reality == my_expectation
18
19    reality = src.telephone.text(True)
20    my_expectation = 'I got: True'
21    assert reality == my_expectation
22
23
24def test_passing_an_integer():

  • I change the call in the assertion of test_passing_an_integer to src.telephone.text

    24def test_passing_an_integer():
25    an_integer = 1234
26    # assert text(an_integer) == f'I got: {an_integer}'
27    reality = src.telephone.text(an_integer)
28    my_expectation = f'I got: {an_integer}'
29    assert reality == my_expectation
30
31
32def test_passing_a_float():

    green.

  • I remove the commented line from test_passing_an_integer

    24def test_passing_an_integer():
25    an_integer = 1234
26
27    reality = src.telephone.text(an_integer)
28    my_expectation = f'I got: {an_integer}'
29    assert reality == my_expectation
30
31
32def test_passing_a_float():

  • I change the call in the assertion of test_passing_a_float

    32def test_passing_a_float():
33    a_float = 5.678
34    # assert text(a_float) == f'I got: {a_float}'
35    reality = src.telephone.text(a_float)
36    my_expectation = f'I got: {a_float}'
37    assert reality == my_expectation
38
39
40def test_passing_a_string():

    still green because when src.telephone.text is called, Python follows this path

    src.telephone.text
src
└── telephone.py
    └── def text(the_input):
        └── return f'I got: {the input}'

    then uses the string representation of the object in the curly braces { }

    a_float = 5.678

text(a_float)
    text(the_input)
        the_input = 5.678
        return f'I got: {the_input}'
        return  'I got:  5.678     '

  • I remove the commented line

    32def test_passing_a_float():
33    a_float = 5.678
34
35    reality = src.telephone.text(a_float)
36    my_expectation = f'I got: {a_float}'
37    assert reality == my_expectation
38
39
40def test_passing_a_string():

    the test is still green.

  • I change the call in the assertion of test_passing_a_string

    40def test_passing_a_string():
41    a_string = 'hi'
42    # assert text(a_string) == f'I got: {a_string}'
43    reality = src.telephone.text(a_string)
44    my_expectation = f'I got: {a_string}'
45    assert reality == my_expectation
46
47
48def test_passing_a_tuple():

  • I remove the commented line

    40def test_passing_a_string():
41    a_string = 'hi'
42
43    reality = src.telephone.text(a_string)
44    my_expectation = f'I got: {a_string}'
45    assert reality == my_expectation
46
47
48def test_passing_a_tuple():

  • I change the call in the assertion of test_passing_a_tuple

    48def test_passing_a_tuple():
49    a_tuple = (0, 1, 2, 'n')
50    # assert text(a_tuple) == f'I got: {a_tuple}'
51    reality = src.telephone.text(a_tuple)
52    my_expectation = f'I got: {a_tuple}'
53    assert reality == my_expectation
54
55
56def test_passing_a_list():

    still green.

  • I remove the commented line

    48def test_passing_a_tuple():
49    a_tuple = (0, 1, 2, 'n')
50
51    reality = src.telephone.text(a_tuple)
52    my_expectation = f'I got: {a_tuple}'
53    assert reality == my_expectation
54
55
56def test_passing_a_list():

  • I change the call in the assertion of test_passing_a_list

    56def test_passing_a_list():
57    a_list = [0, 1, 2, 'n']
58    # assert text(a_list) == f'I got: {a_list}'
59    reality = src.telephone.text(a_list)
60    my_expectation = f'I got: {a_list}'
61    assert reality == my_expectation
62
63
64def test_passing_a_set():

    green.

  • I remove the commented line

    56def test_passing_a_list():
57    a_list = [0, 1, 2, 'n']
58
59    reality = src.telephone.text(a_list)
60    my_expectation = f'I got: {a_list}'
61    assert reality == my_expectation
62
63
64def test_passing_a_set():

  • I change the call in the assertion of test_passing_a_set

    64def test_passing_a_set():
65    a_set = {0, 1, 2, 'n'}
66    # assert text(a_set) == f'I got: {a_set}'
67    reality = src.telephone.text(a_set)
68    my_expectation = f'I got: {a_set}'
69    assert reality == my_expectation
70
71
72def test_passing_a_dictionary():

    still green.

  • I remove the commented line

    64def test_passing_a_set():
65    a_set = {0, 1, 2, 'n'}
66
67    reality = src.telephone.text(a_set)
68    my_expectation = f'I got: {a_set}'
69    assert reality == my_expectation
70
71
72def test_passing_a_dictionary():

  • I change the call in reality for test_passing_a_dictionary

    72def test_passing_a_dictionary():
73    a_dictionary = {
74        'key0': 'value0',
75        'keyN': [0, 1, 2, 'n'],
76    }
77    # reality = text(a_dictionary)
78    reality = src.telephone.text(a_dictionary)
79    my_expectation = f'I got: {a_dictionary}'
80    assert reality == my_expectation
81
82
83def test_passing_a_class():

    the test is still green because when src.telephone.text is called, Python follows this path

    src.telephone.text
src
└── telephone.py
    └── def text(the_input):
        └── return f'I got: {the input}'

    then uses the string representation of the object in the curly braces { }

    a_dictionary = {
    'key0': 'value0',
    'keyN': [0, 1, 2, 'n'],
}

text(a_dictionary)
    text(the_input)
        the_input = {
            'key0': 'value0',
            'keyN': [0, 1, 2, 'n'],
        }
        return f'I got: {the_input}'
        return  "I got: {'key0': 'value0', 'keyN': [0, 1, 2, 'n']}"

  • I remove the commented line

    72def test_passing_a_dictionary():
73    a_dictionary = {
74        'key0': 'value0',
75        'keyN': [0, 1, 2, 'n'],
76    }
77
78    reality = src.telephone.text(a_dictionary)
79    my_expectation = f'I got: {a_dictionary}'
80    assert reality == my_expectation
81
82
83def test_passing_a_class():

  • I change the calls in the assertions of test_passing_a_class

     83def test_passing_a_class():
 84    # assert text(object) == "I got: <class 'object'>"
 85    reality = src.telephone.text(object)
 86    my_expectation = "I got: <class 'object'>"
 87    assert reality == my_expectation
 88
 89    # assert text(bool) == "I got: <class 'bool'>"
 90    reality = src.telephone.text(bool)
 91    my_expectation = "I got: <class 'bool'>"
 92    assert reality == my_expectation
 93
 94    # assert text(int) == "I got: <class 'int'>"
 95    reality = src.telephone.text(int)
 96    my_expectation = "I got: <class 'int'>"
 97    assert reality == my_expectation
 98
 99    # assert text(float) == "I got: <class 'float'>"
100    reality = src.telephone.text(float)
101    my_expectation = "I got: <class 'float'>"
102    assert reality == my_expectation
103
104    # assert text(str) == "I got: <class 'str'>"
105    reality = src.telephone.text(str)
106    my_expectation = "I got: <class 'str'>"
107    assert reality == my_expectation
108
109    # assert text(tuple) == "I got: <class 'tuple'>"
110    reality = src.telephone.text(tuple)
111    my_expectation = "I got: <class 'tuple'>"
112    assert reality == my_expectation
113
114    # assert text(list) == "I got: <class 'list'>"
115    reality = src.telephone.text(list)
116    my_expectation = "I got: <class 'list'>"
117    assert reality == my_expectation
118
119    # assert text(set) == "I got: <class 'set'>"
120    reality = src.telephone.text(set)
121    my_expectation = "I got: <class 'set'>"
122    assert reality == my_expectation
123
124    # assert text(dict) == "I got: <class 'dict'>"
125    reality = src.telephone.text(dict)
126    my_expectation = "I got: <class 'dict'>"
127    assert reality == my_expectation
128
129
130# Exceptions seen

    the test is still green.

  • I remove the commented lines

  • I remove the text function from test_telephone.py

     1import src.telephone
 2
 3
 4def test_passing_none():
 5    reality = src.telephone.text(None)
 6    my_expectation = 'I got: None'
 7    assert reality == my_expectation
 8
 9
10def test_passing_booleans():

    all the tests are still green because all the calls to the text function that was in test_telephone.py are now to the text function in telephone.py in the src folder. When src.telephone.text is called Python follows this path

    src.telephone.text
src
└── telephone.py
    └── def text(the_input):
        └── return f'I got: {the input}'

  • I add a git commit message in the other terminal

    git commit -am \
'separate solution from tests'

    the terminal shows a summary of the changes then goes back to the command line.

I can write solutions in a different module from the tests.

test_telephone

Now that the solution is separate from the tests, I can write the program that makes the tests pass without looking at test_telephone.py.

RED: make it fail

  • I close test_telephone.py

  • I delete the text in telephone.py and the terminal shows 9 failures. I start with the last AttributeError

    FAILED ...::test_passing_none -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_booleans -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_an_integer -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_float -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_string -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_tuple -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_list -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_set -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_dictionary -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
FAILED ...::test_passing_a_class -
    AttributeError: module 'src.telephone'
                    has no attribute 'text'
=================== 10 failed in A.BCs ===================

    Can you make the tests pass without looking at how I solve it below? You can come back to compare solutions when you are done or if you get stuck.

GREEN: make it pass

  • I add the name to telephone.py

    1text

    the terminal is my friend, and shows NameError

    NameError: name 'text' is not defined

  • I point it to None (the simplest object) to define it

    1# text
2text = None

    the terminal is my friend, and shows TypeError

    TypeError: 'NoneType' object is not callable

    because text points to None and I cannot call None like a function.

  • I make text a function to make it callable

    1# text
2# text = None
3def text():
4    return None

    the terminal is my friend, and shows TypeError

    TypeError: text() takes 0 positional arguments
           but 1 was given

    because this function definition does not allow any inputs, the parentheses are empty.

  • I make the function take input

    1# text
2# text = None
3# def text():
4def text(value):
5    return None

    the terminal is my friend, and shows AssertionError

    E       assert None == "I got: <class 'object'>"

  • I copy the string from the terminal and paste it in the return statement to match the expectation of the test

    1# text
2# text = None
3# def text():
4def text(value):
5    # return None
6    return "I got: <class 'object'>"

    the terminal is my friend, and shows AssertionError

    E       assert "I got: <class 'object'>"
            == "I got: <class 'bool'>"

  • I change the return statement to see the difference between the input and the expected output (remember the identity function?)

    1# text
2# text = None
3# def text():
4def text(value):
5    # return None
6    # return "I got: <class 'object'>"
7    return value

    the test summary info shows that every test has AssertionError

    FAILED ...::test_passing_none -
    AssertionError: assert None == 'I got: None'
FAILED ...::test_passing_booleans -
    AssertionError: assert False == 'I got: False'
FAILED ...::test_passing_an_integer -
    AssertionError: assert 1234 == 'I got: 1234'
FAILED ...::test_passing_a_float -
    AssertionError: assert 5.678 == 'I got: 5.678'
FAILED ...::test_passing_a_string -
    AssertionError: assert 'hi' == 'I got: hi'
FAILED ...::test_passing_a_tuple -
    assert (0, 1, 2, 'n') == "I got: (0, 1, 2, 'n')"
FAILED ...::test_passing_a_list -
    assert [0, 1, 2, 'n'] == "I got: [0, 1, 2, 'n']"
FAILED ...::test_passing_a_set -
    assert {0, 1, 2, 'n'} == "I got: {0, 1, 2, 'n'}"
FAILED ...::test_passing_a_dictionary -
    assert {'key0': 'value0', 'keyN': [0, 1, 2, 'n']}
== "I got: {'key0': 'value0',...
FAILED ...::test_passing_a_class -
    assert <class 'object'> == "I got: <class 'object'>"

    they all expect the input (value) as part of the message

  • I add a return statement with an f-string

    1# text
2# text = None
3# def text():
4def text(value):
5    # return None
6    # return "I got: <class 'object'>"
7    # return value
8    return f'I got: {value}'

    and all the tests are passing! I am a programmer!!

  • I remove the commented lines

    1def text(value):
2    return f'I got: {value}'

  • I add a git commit message in the other terminal

    git commit --all --message 'test telephone'

    the terminal shows a summary of the changes then goes back to the command line.

close the project

  • I close telephone.py

  • I click in the terminal where the tests are running

  • I use q on the keyboard to leave the tests. The terminal goes back to the command line.

  • I change directory to the parent of telephone

    cd ..

    the terminal shows

    .../pumping_python

    I am back in the pumping_python directory.

review

I can write solutions in a different module from the tests.

code from the chapter

Do you want to see all the CODE I typed in this chapter?

what is next?

You now know:

would you like to test making a person with f-strings?

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