---

---

---

separate and equal telephone

The text function in the telephone project was written in tests/test_telephone.py. I want to move it to __init__.py in the telephone folder 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

telephone/tests/test_telephone.py

import src.telephone


text = src.telephone.text


def assert_equal(a, b):
    assert a == b


def test_passing_none():
    assert_equal(text(None), 'I got: None')

telephone/tests/test_telephone.py

def test_passing_booleans():
    assert_equal(text(False), 'I got: False')
    assert_equal(text(True), 'I got: True')


def test_passing_an_integer():
    an_integer = 1234
    assert_equal(text(an_integer), f'I got: {an_integer}')


def test_passing_a_float():
    a_float = 5.678
    assert_equal(text(a_float), f'I got: {a_float}')

telephone/tests/test_telephone.py

def test_passing_a_string():
    a_string = 'hello'
    assert_equal(text('hello'), f'I got: {a_string}')


def test_passing_a_tuple():
    a_tuple = (0, 1, 2, 'n')
    assert_equal(text(a_tuple), f"I got: {a_tuple}")


def test_passing_a_list():
    a_list = [0, 1, 2, 'n']
    assert_equal(text(a_list), f'I got: {a_list}')

telephone/tests/test_telephone.py

def test_passing_a_set():
    a_set = {0, 1, 2, 'n'}
    assert_equal(text(a_set), f'I got: {a_set}')


def test_passing_a_dictionary():
    a_dictionary = {
        'key0': 'value0',
        'keyN': [0, 1, 2, 'n'],
    }
    reality = text(a_dictionary)
    my_expectation = f'I got: {a_dictionary}'
    assert_equal(reality, my_expectation)

telephone/tests/test_telephone.py

def test_passing_a_class():
    assert_equal(
        text(object), "I got: <class 'object'>"
    )
    assert_equal(text(bool), "I got: <class 'bool'>")
    assert_equal(text(int), "I got: <class 'int'>")
    assert_equal(text(float), "I got: <class 'float'>")
    assert_equal(text(str), "I got: <class 'str'>")
    assert_equal(text(tuple), "I got: <class 'tuple'>")
    assert_equal(text(list), "I got: <class 'list'>")
    assert_equal(text(set), "I got: <class 'set'>")
    assert_equal(text(dict), "I got: <class 'dict'>")


# Exceptions seen
# AssertionError
# NameError
# TypeError
# AttributeError

---

open the project

• I open a terminal

• I change directory to the project

  cd telephone
  

  the terminal shows I am in the telephone folder

  .../pumping_python/telephone
  

• I open test_telephone.py from the tests folder

• I use pytest-watcher to run the tests automatically

  uv run pytest-watcher . --now
  

  the terminal shows

  test_telephone.py ..........                        [100%]
  
  =================== 10 passed in A.BCs ===================
  

---

move text

RED: make it fail

---

I comment out the text function in tests/test_telephone.py

def assert_equal(a, b):
    assert a == b


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


def test_passing_none():

the terminal is my friend, and shows NameError

NameError: name 'text' is not defined

---

GREEN: make it pass

---

• I use a variable to reroute the calls to the text function to the text function of the telephone module in the src folder

  text = src.telephone.text
  
  
  def assert_equal(a, b):
  

  the terminal is my friend, and shows NameError

  NameError: name 'src' is not defined
  

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

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

  import src.telephone
  
  
  text = src.telephone.text
  

  the terminal is my friend, and shows AttributeError

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

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

• I add AttributeError to the list of Exceptions seen

  # Exceptions seen
  # AssertionError
  # NameError
  # TypeError
  # AttributeError
  

• I open __init__.py from the telephone folder in the src folder

• I delete all the text in the file then add a copy of the text function to src/telephone/__init__.py

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

  all the tests are green again because

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

  • Python calls the text function from the object it imported for the src/telephone/__init__.py file (src.telephone) when src.telephone.text is called.

  I think of src.telephone.text like an address

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

  • text is something in the telephone module, in this case it is a function in the __init__.py file.

  • telephone is something in src, in this case it is a folder in the src folder.

  • src is something Python can import (a module, Python package or folder).

---

REFACTOR: make it better

---

• I remove the commented lines from tests/test_telephone.py

  import src.telephone
  
  
  text = src.telephone.text
  
  
  def assert_equal(a, b):
      assert a == b
  
  
  def test_passing_none():
  

• I add a git commit message in the other terminal

  git commit -am \
  'move text function to src'
  

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

All the tests are passing because Python follows this path when the text function is called

• In test_passing_none

  text = src.telephone.text
  text(None) -> 'I got: None'
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = None
                  └── return f'I got: {the_input}'
                      return  'I got:  None      '
  

• In test_passing_booleans

  text = src.telephone.text
  text(False) -> 'I got: False'
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = False
                  └── return f'I got: {the_input}'
                      return  'I got:  False     '
  

• In test_passing_an_integer

  text = src.telephone.text
  an_integer = 1234
  text(an_integer) -> 'I got: 1234'
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = 1234
                  └── return f'I got: {the_input}'
                      return  'I got: 1234       '
  

• In test_passing_a_float

  text = src.telephone.text
  a_float = 5.678
  text(a_float) -> 'I got: 5.678'
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = 5.678
                  └── return f'I got: {the_input}'
                      return  'I got: 5.678      '
  

• In test_passing_a_string

  text = src.telephone.text
  a_string = 'hello'
  text(a_string) -> 'I got: hello'
  src/
  └── telephone/
      └── __init__.py
          └── def text(the_input):
              ├── the_input = 'hello'
              └── return f'I got: {the_input}'
                  return  'I got:  hello     '
  

• In test_passing_a_tuple

  text = src.telephone.text
  a_tuple = (0, 1, 2, 'n')
  text(a_tuple) -> "I got: (0, 1, 2, 'n')"
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = (0, 1, 2, 'n')
                  └── return f'I got: {  the_input  }'
                      return  "I got:  (0, 1, 2, 'n')"
  

• In test_passing_a_list

  text = src.telephone.text
  a_list = [0, 1, 2, 'n']
  text(a_list) -> "I got: [0, 1, 2, 'n']"
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = [0, 1, 2, 'n']
                  └── return f'I got: {  the_input  }'
                      return  "I got:  [0, 1, 2, 'n']"
  

• In test_passing_a_set

  text = src.telephone.text
  a_set = {0, 1, 2, 'n'}
  text(a_set) -> 'I got: {0, 1, 2, 'n'}'
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = {0, 1, 2, 'n'}
                  └── return f'I got: {  the_input  }'
                      return  'I got:  {0, 1, 2, 'n'}'
  

• In test_passing_a_dictionary

  text = src.telephone.text
  a_dictionary = {
      'key0': 'value0', 'keyN': [0, 1, 2, 'n']
  }
  text(a_dictionary) -> ("I got: {'key0': 'value0',"
  │                               'keyN': [0, 1, 2, 'n']}")
  └── src/
      └── telephone/
          └── __init__.py
              └── def 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']}")
  

• In test_passing_a_class

  text = src.telephone.text
  text(object) -> "I got: <class 'object'>"
  └── src/
      └── telephone/
          └── __init__.py
              └── def text(the_input):
                  ├── the_input = object
                  └── return f'I got: {   the_input   }'
                      return  "I got:  <class 'object'>"
  

---

test_telephone

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

---

RED: make it fail

---

• I close tests/test_telephone.py

• I delete the text in src/telephone/__init__.py and the terminal AttributeError

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

  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 src/telephone/__init__.py

  text
  

  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

  # text
  text = 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

  # text
  # text = None
  def text():
      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

  # text
  # text = None
  # def text():
  def text(value):
      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

  # text
  # text = None
  # def text():
  def text(value):
      # return None
      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?)

  # text
  # text = None
  # def text():
  def text(value):
      # return None
      # return "I got: <class 'object'>"
      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 'hello' == 'I got: hello'
  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', 'keyN': [0, 1, 2, 'n']}"
  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 the name of the input

  # text
  # text = None
  # def text():
  def text(value):
      # return None
      # return "I got: <class 'object'>"
      # return value
      return 'I got: value'
  

  the terminal is my friend, and shows AssertionError

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

• I change the return statement to an f-string

  # text
  # text = None
  # def text():
  def text(value):
      # return None
      # return "I got: <class 'object'>"
      # return value
      # return 'I got: value'
      return f'I got: {value}'
  

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

• I remove the commented lines

  def text(value):
      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 src/telephone/__init__.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?

• I know how to make a Python Test Driven Development environment manually.

• I know what a Python module is.

• I know how to run tests automatically.

• I know what an assertion is.

• I know how to make functions.

• I know how to make a person with strings.

• I know how to make functions that take input.

• I know what causes TypeError.

• I know how to place values in strings.

• I know how to separate tests from solutions.

would you like to separate the tests from the solution in the TypeError project?

---

rate pumping python

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---

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