test person with unittest

I want to use the unittest library in the person project.

preview

I have these tests by the end of the chapter

person/tests/test_person.py
 1import src.person
 2import unittest
 3
 4
 5class TestPerson(unittest.TestCase):
 6
 7    def assert_person_factory_works(
 8            self, first_name, last_name,
 9            sex, year_of_birth
10        ):
11        self.assertEqual(
12            src.person.person(
13                first_name=first_name,
14                last_name=last_name,
15                sex=sex,
16                year_of_birth=year_of_birth,
17            ),
18            (
19                f'{first_name}, {last_name},'
20                f' {sex}, {year_of_birth}'
21            )
22        )
person/tests/test_person.py
24    def assert_say_hello_works(
25            self, first_name, last_name,
26            year_of_birth,
27        ):
28        self.assertEqual(
29            src.person.say_hello(
30                first_name=first_name,
31                last_name=last_name,
32                year_of_birth=year_of_birth
33            ),
34            (
35                f'Hello, my name is {first_name}'
36                f' {last_name} and I am'
37                f' {2026-year_of_birth}.'
38            )
39        )
person/tests/test_person.py
41    def assert_person_can_say_hello(
42            self,first_name, last_name,
43            sex, year_of_birth,
44        ):
45        self.assertEqual(
46            src.person.Person(
47                first_name=first_name,
48                last_name=last_name,
49                sex=sex,
50                year_of_birth=year_of_birth,
51            ).say_hello(),
52            (
53                f'Hello, my name is {first_name}'
54                f' {last_name} and I am'
55                f' {2026-year_of_birth}.'
56            )
57        )
person/tests/test_person.py
59    def test_joe(self):
60        first_name = 'joe'
61        last_name = 'blow'
62        sex = 'M'
63        year_of_birth = 1996
64
65        self.assert_person_factory_works(
66            first_name=first_name,
67            last_name=last_name,
68            sex=sex,
69            year_of_birth=year_of_birth
70        )
71
72        self.assert_say_hello_works(
73            first_name=first_name,
74            last_name=last_name,
75            year_of_birth=year_of_birth,
76        )
77
78        self.assert_person_can_say_hello(
79            first_name=first_name,
80            last_name=last_name,
81            sex=sex,
82            year_of_birth=year_of_birth
83        )
person/tests/test_person.py
 85    def test_jane(self):
 86        first_name = 'jane'
 87        last_name = 'doe'
 88        sex = 'F'
 89        year_of_birth = 1991
 90
 91        self.assert_person_factory_works(
 92            first_name=first_name,
 93            last_name=last_name,
 94            sex=sex,
 95            year_of_birth=year_of_birth,
 96        )
 97
 98        self.assert_say_hello_works(
 99            first_name=first_name,
100            last_name=last_name,
101            year_of_birth=year_of_birth,
102        )
103
104        self.assert_person_can_say_hello(
105            first_name=first_name,
106            last_name=last_name,
107            sex=sex,
108            year_of_birth=year_of_birth,
109        )
person/tests/test_person.py
111    def test_john(self):
112        first_name = 'john'
113        last_name = 'smith'
114        sex = 'M'
115        year_of_birth = 1580
116
117        self.assert_person_factory_works(
118            first_name=first_name,
119            last_name=last_name,
120            sex=sex,
121            year_of_birth=year_of_birth,
122        )
123
124        self.assert_say_hello_works(
125            first_name=first_name,
126            last_name=last_name,
127            year_of_birth=year_of_birth,
128        )
129
130        self.assert_person_can_say_hello(
131            first_name=first_name,
132            last_name=last_name,
133            sex=sex,
134            year_of_birth=year_of_birth,
135        )
person/tests/test_person.py
137    def test_mary(self):
138        first_name = 'mary'
139        last_name = 'public'
140        sex = 'F'
141        year_of_birth = 2000
142
143        self.assert_person_factory_works(
144            first_name=first_name,
145            last_name=last_name,
146            sex=sex,
147            year_of_birth=year_of_birth,
148        )
149
150        self.assert_say_hello_works(
151            first_name=first_name,
152            last_name=last_name,
153            year_of_birth=year_of_birth,
154        )
155
156        self.assert_person_can_say_hello(
157            first_name=first_name,
158            last_name=last_name,
159            sex=sex,
160            year_of_birth=year_of_birth,
161        )
person/tests/test_person.py
163    def test_dir_person_class(self):
164        self.assertEqual(
165            dir(src.person.Person),
166            [
167                '__class__', '__delattr__', '__dict__',
168                '__dir__', '__doc__', '__eq__',
169                '__firstlineno__', '__format__', '__ge__',
170                '__getattribute__', '__getstate__', '__gt__',
171                '__hash__', '__init__', '__init_subclass__',
172                '__le__', '__lt__', '__module__', '__ne__',
173                '__new__', '__reduce__', '__reduce_ex__',
174                '__repr__', '__setattr__', '__sizeof__',
175                '__static_attributes__', '__str__',
176                '__subclasshook__', '__weakref__', 'say_hello'
177            ]
178        )
person/tests/test_person.py
180    def test_dir_person_instance(self):
181        self.assertEqual(
182            dir(
183                src.person.Person(
184                    first_name='first_name',
185                    last_name='last_name',
186                    sex='M',
187                    year_of_birth=2026,
188                )
189            ),
190            [
191                '__class__', '__delattr__', '__dict__',
192                '__dir__', '__doc__', '__eq__',
193                '__firstlineno__', '__format__', '__ge__',
194                '__getattribute__', '__getstate__', '__gt__',
195                '__hash__', '__init__', '__init_subclass__',
196                '__le__', '__lt__', '__module__', '__ne__',
197                '__new__', '__reduce__', '__reduce_ex__',
198                '__repr__', '__setattr__', '__sizeof__',
199                '__static_attributes__', '__str__',
200                '__subclasshook__', '__weakref__', 'first_name',
201                'last_name', 'say_hello', 'sex', 'year_of_birth',
202            ]
203        )
204
205
206# Exceptions seen
207# AssertionError
208# NameError
209# TypeError
210# AttributeError
211# SyntaxError

open the project

  • I open a terminal

  • I change directory to the project

    cd person

  • I open test_person.py from the tests folder

  • I use pytest-watcher to run the tests automatically

    uv run pytest-watcher . --now

    the terminal shows

    tests/test_person.py ......                         [100%]

=================== 6 passed in A.BCs ====================

add TestPerson class

RED: make it fail

I add an object named TestPerson to test_person.py

45def assert_person_factory_works(
46        first_name, last_name,
47        sex, year_of_birth
48    ):
49    assert_equal(
50        src.person.person(
51            first_name=first_name,
52            last_name=last_name,
53            sex=sex,
54            year_of_birth=year_of_birth,
55        ),
56        (
57            f'{first_name}, {last_name},'
58            f' {sex}, {year_of_birth}'
59        )
60    )
61
62
63class TestPerson(object):
64
65    def test_failure(self):
66        self.assertEqual(False, True)
67
68
69def test_joe():

the terminal is my friend, and shows AttributeError

AttributeError: 'TestPerson' object
                has no attribute 'assertEqual'

GREEN: make it pass

  • I add unittest.TestCase as the parent object of TestPerson

    63# class TestPerson(object):
64class TestPerson(unittest.TestCase):
65
66    def test_failure(self):
67        self.assertEqual(False, True)

    the terminal is my friend, and shows NameError

    NameError: name 'unittest' is not defined.
           Did you forget to import 'unittest'?

  • I add an import statement at the top of the file

    1import src.person
2import unittest
3
4
5def assert_equal(left, right):
6    assert left == right

    the terminal is my friend, and shows AssertionError

    AssertionError: False != True

  • I change False to True in the assertion

    64# class TestPerson(object):
65class TestPerson(unittest.TestCase):
66
67    def test_failure(self):
68        # self.assertEqual(False, True)
69        self.assertEqual(True, True)
70
71
72def test_joe():

    the test passes.

REFACTOR: make it better

  • I remove the commented lines

    46def assert_person_factory_works(
47        first_name, last_name,
48        sex, year_of_birth
49    ):
50    assert_equal(
51        src.person.person(
52            first_name=first_name,
53            last_name=last_name,
54            sex=sex,
55            year_of_birth=year_of_birth,
56        ),
57        (
58            f'{first_name}, {last_name},'
59            f' {sex}, {year_of_birth}'
60        )
61    )
62
63
64class TestPerson(unittest.TestCase):
65
66    def test_failure(self):
67        self.assertEqual(True, True)
68
69
70def test_joe():

  • I open a new terminal then make sure I am in the person folder

    cd person

  • I add a git commit message in the new terminal

    git commit -am \
'add TestPerson class'

move test_joe to TestPerson

RED: make it fail

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

  • I remove test_failure from the TestPerson class

  • I move test_joe to make it a method of the TestPerson class

    64class TestPerson(unittest.TestCase):
65
66    def test_joe():
67        first_name = 'joe'
68        last_name = 'blow'
69        sex = 'M'
70        year_of_birth = 1996
71
72        assert_person_factory_works(
73            first_name=first_name,
74            last_name=last_name,
75            sex=sex,
76            year_of_birth=year_of_birth
77        )
78
79        assert_say_hello_works(
80            first_name=first_name,
81            last_name=last_name,
82            year_of_birth=year_of_birth,
83        )
84
85        assert_person_can_say_hello(
86            first_name=first_name,
87            last_name=last_name,
88            sex=sex,
89            year_of_birth=year_of_birth
90        )
91
92
93def test_jane():

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_joe() takes
           0 positional arguments but 1 was given

    because a method of an instance takes the instance of the class (self) it belongs to as the first argument.

GREEN: make it pass

  • I add the staticmethod decorator to test_joe because …

    64class TestPerson(unittest.TestCase):
65
66    @staticmethod
67    def test_joe():
68        first_name = 'joe'

    the test is green again.

  • I add a git commit message in the other terminal

    git commit -am 'move test_joe to TestPerson'

move test_jane to TestPerson

RED: make it fail

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

  • I move test_jane to make it a method of the TestPerson class

     86        assert_person_can_say_hello(
 87            first_name=first_name,
 88            last_name=last_name,
 89            sex=sex,
 90            year_of_birth=year_of_birth
 91        )
 92
 93    def test_jane():
 94        first_name = 'jane'
 95        last_name = 'doe'
 96        sex = 'F'
 97        year_of_birth = 1991
 98
 99        assert_person_factory_works(
100            first_name=first_name,
101            last_name=last_name,
102            sex=sex,
103            year_of_birth=year_of_birth,
104        )
105
106        assert_say_hello_works(
107            first_name=first_name,
108            last_name=last_name,
109            year_of_birth=year_of_birth,
110        )
111
112        assert_person_can_say_hello(
113            first_name=first_name,
114            last_name=last_name,
115            sex=sex,
116            year_of_birth=year_of_birth,
117        )
118
119
120def test_john():

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_jane() takes
           0 positional arguments but 1 was given

    because …

GREEN: make it pass

  • I add the staticmethod decorator to test_jane since it also does not use anything in the TestPerson class, yet

    86        assert_person_can_say_hello(
87            first_name=first_name,
88            last_name=last_name,
89            sex=sex,
90            year_of_birth=year_of_birth
91        )
92
93    @staticmethod
94    def test_jane():

    the test passes.

  • I add a git commit message in the other terminal

    git commit -am 'move test_jane to TestPerson'

move test_john to TestPerson

RED: make it fail

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

  • I move test_john to make it a method of the TestPerson class

    113        assert_person_can_say_hello(
114            first_name=first_name,
115            last_name=last_name,
116            sex=sex,
117            year_of_birth=year_of_birth,
118        )
119
120    def test_john():
121        first_name = 'john'
122        last_name = 'smith'
123        sex = 'M'
124        year_of_birth = 1580
125
126        assert_person_factory_works(
127            first_name=first_name,
128            last_name=last_name,
129            sex=sex,
130            year_of_birth=year_of_birth,
131        )
132
133        assert_say_hello_works(
134            first_name=first_name,
135            last_name=last_name,
136            year_of_birth=year_of_birth,
137        )
138
139        assert_person_can_say_hello(
140            first_name=first_name,
141            last_name=last_name,
142            sex=sex,
143            year_of_birth=year_of_birth,
144        )
145
146
147def test_mary():

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_john() takes
           0 positional arguments but 1 was given

    because a method of an instance takes the instance of the class (self) it belongs to as the first argument.

GREEN: make it pass

  • I also add the staticmethod decorator to test_john

    113        assert_person_can_say_hello(
114            first_name=first_name,
115            last_name=last_name,
116            sex=sex,
117            year_of_birth=year_of_birth,
118        )
119
120    @staticmethod
121    def test_john():

    green again.

  • I add a git commit message in the other terminal

    git commit -am 'move test_john to TestPerson'

move test_mary to TestPerson

RED: make it fail

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

  • I move test_mary to make it a method of the TestPerson class

    140        assert_person_can_say_hello(
141            first_name=first_name,
142            last_name=last_name,
143            sex=sex,
144            year_of_birth=year_of_birth,
145        )
146
147    def test_mary():
148        first_name = 'mary'
149        last_name = 'public'
150        sex = 'F'
151        year_of_birth = 2000
152
153        assert_person_factory_works(
154            first_name=first_name,
155            last_name=last_name,
156            sex=sex,
157            year_of_birth=year_of_birth,
158        )
159
160        assert_say_hello_works(
161            first_name=first_name,
162            last_name=last_name,
163            year_of_birth=year_of_birth,
164        )
165
166        assert_person_can_say_hello(
167            first_name=first_name,
168            last_name=last_name,
169            sex=sex,
170            year_of_birth=year_of_birth,
171        )
172
173
174def test_dir_person_class():

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_mary() takes
           0 positional arguments but 1 was given

    because a method of an instance takes the instance of the class (self) it belongs to as the first argument.

GREEN: make it pass

  • I add the staticmethod decorator to test_mary because I can use it when a method does not use anything in the object it belongs to

    140        assert_person_can_say_hello(
141            first_name=first_name,
142            last_name=last_name,
143            sex=sex,
144            year_of_birth=year_of_birth,
145        )
146
147    @staticmethod
148    def test_mary():

    green.

  • I add a git commit message in the other terminal

    git commit -am 'move test_mary to TestPerson'

test_dir_person_class with unittest

RED: make it fail

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

  • I move test_dir_person_class to make it a method of the TestPerson class

    167        assert_person_can_say_hello(
168            first_name=first_name,
169            last_name=last_name,
170            sex=sex,
171            year_of_birth=year_of_birth,
172        )
173
174    def test_dir_person_class():
175        assert_equal(
176            dir(src.person.Person),
177            [
178                '__class__', '__delattr__', '__dict__',

    187                '__subclasshook__', '__weakref__', 'say_hello'
188            ]
189        )
190
191
192def test_dir_person_instance():

    the terminal is my friend, and shows TypeError

    TypeError:
    TestPerson.test_dir_person_class()
    takes 0 positional arguments but 1 was given

    because a method of an instance takes the instance of the class (self) it belongs to as the first argument.

GREEN: make it pass

I add self to the parentheses of test_dir_person_class

167        assert_person_can_say_hello(
168            first_name=first_name,
169            last_name=last_name,
170            sex=sex,
171            year_of_birth=year_of_birth,
172        )
173
174    # def test_dir_person_class():
175    def test_dir_person_class(self):
176        assert_equal(
177            dir(src.person.Person),
178            [
179                '__class__', '__delattr__', '__dict__',

green again.

REFACTOR: make it better

  • I change the call to my assert_equal function to the assertNotEqual method of the unittest.TestCase class in test_dir_person_class

    174    # def test_dir_person_class():
175    def test_dir_person_class(self):
176        # assert_equal(
177        self.assertNotEqual(
178            dir(src.person.Person),
179            [
180                '__class__', '__delattr__', '__dict__',

    the terminal is my friend, and shows AssertionError.

  • I change assertNotEqual to assertEqual in test_dir_person_class

    174    # def test_dir_person_class():
175    def test_dir_person_class(self):
176        # assert_equal(
177        # self.assertNotEqual(
178        self.assertEqual(
179            dir(src.person.Person),
180            [
181                '__class__', '__delattr__', '__dict__',

    the test passes.

  • I remove the commented lines from test_dir_person_class

    167        assert_person_can_say_hello(
168            first_name=first_name,
169            last_name=last_name,
170            sex=sex,
171            year_of_birth=year_of_birth,
172        )
173
174    def test_dir_person_class(self):
175        self.assertEqual(
176            dir(src.person.Person),
177            [
178                '__class__', '__delattr__', '__dict__',

    187                '__subclasshook__', '__weakref__', 'say_hello'
188            ]
189        )
190
191
192def test_dir_person_instance():

  • I add a git commit message in the other terminal

    git commit -am
'move test_dir_person_class to TestPerson'

test_dir_person_instance with unittest

RED: make it fail

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

  • I move test_dir_person_instance to make it a method of the TestPerson class

    187                '__subclasshook__', '__weakref__', 'say_hello'
188            ]
189        )
190
191    def test_dir_person_instance():
192        assert_equal(
193            dir(
194                src.person.Person(
195                    first_name='first_name',
196                    last_name='last_name',
197                    sex='M',
198                    year_of_birth=2026,
199                )
200            ),
201            [
202                '__class__', '__delattr__', '__dict__',

    212                'last_name', 'say_hello', 'sex', 'year_of_birth',
213            ]
214        )
215
216
217# Exceptions seen

    the terminal is my friend, and shows TypeError

    TypeError:
    TestPerson.test_dir_person_instance()
    takes 0 positional arguments but 1 was given

    because …

GREEN: make it pass

I add self to the parentheses of test_dir_person_instance

187                '__subclasshook__', '__weakref__', 'say_hello'
188            ]
189        )
190
191    # def test_dir_person_instance():
192    def test_dir_person_instance(self):
193        assert_equal(
194            dir(
195                src.person.Person(
196                    first_name='first_name',
197                    last_name='last_name',
198                    sex='M',
199                    year_of_birth=2026,
200                )
201            ),
202            [
203                '__class__', '__delattr__', '__dict__',

the test is green again.

REFACTOR: make it better

  • I change the call to my assert_equal function to the assertNotEqual method of the unittest.TestCase class in test_dir_person_instance

    191    # def test_dir_person_instance():
192    def test_dir_person_instance(self):
193        # assert_equal(
194        self.assertNotEqual(
195            dir(
196                src.person.Person(
197                    first_name='first_name',
198                    last_name='last_name',
199                    sex='M',
200                    year_of_birth=2026,
201                )
202            ),
203            [
204                '__class__', '__delattr__', '__dict__',

    the terminal is my friend, and shows AssertionError.

  • I change assertNotEqual to assertEqual in test_dir_person_instance

    191    # def test_dir_person_instance():
192    def test_dir_person_instance(self):
193        # assert_equal(
194        # self.assertNotEqual(
195        self.assertEqual(
196            dir(
197                src.person.Person(
198                    first_name='first_name',
199                    last_name='last_name',
200                    sex='M',
201                    year_of_birth=2026,
202                )
203            ),
204            [
205                '__class__', '__delattr__', '__dict__',

    the test passes.

  • I remove the commented lines from test_dir_person_instance

    187                '__subclasshook__', '__weakref__', 'say_hello'
188            ]
189        )
190
191    def test_dir_person_instance(self):
192        self.assertEqual(
193            dir(
194                src.person.Person(
195                    first_name='first_name',
196                    last_name='last_name',
197                    sex='M',
198                    year_of_birth=2026,
199                )
200            ),
201            [
202                '__class__', '__delattr__', '__dict__',

    212                'last_name', 'say_hello', 'sex', 'year_of_birth',
213            ]
214        )
215
216
217# Exceptions seen
218# AssertionError
219# NameError
220# TypeError
221# AttributeError
222# SyntaxError

  • I add a git commit message in the other terminal

    git commit -am
'move test_dir_person_instance to TestPerson'

move assert_person_can_say_hello to TestPerson

RED: make it fail

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

  • I add a copy of the assert_person_can_say_hello function to make it a method of the TestPerson class

    64class TestPerson(unittest.TestCase):
65
66    def assert_person_can_say_hello(
67            first_name, last_name,
68            sex, year_of_birth,
69        ):
70        assert_equal(
71            src.person.Person(
72                first_name=first_name,
73                last_name=last_name,
74                sex=sex,
75                year_of_birth=year_of_birth,
76            ).say_hello(),
77            (
78                f'Hello, my name is {first_name}'
79                f' {last_name} and I am'
80                f' {2026-year_of_birth}.'
81            )
82        )
83
84    @staticmethod
85    def test_joe():

  • I change the call from the assert_person_can_say_hello function to the assert_person_can_say_hello method of the TestPerson class in test_joe

    84    @staticmethod
85    def test_joe():
86        first_name = 'joe'
87        last_name = 'blow'
88        sex = 'M'
89        year_of_birth = 1996
90
91        assert_person_factory_works(
92            first_name=first_name,
93            last_name=last_name,
94            sex=sex,
95            year_of_birth=year_of_birth
96        )

     98        assert_say_hello_works(
 99            first_name=first_name,
100            last_name=last_name,
101            year_of_birth=year_of_birth,
102        )
103
104        # assert_person_can_say_hello(
105        self.assert_person_can_say_hello(
106            first_name=first_name,
107            last_name=last_name,
108            sex=sex,
109            year_of_birth=year_of_birth
110        )
111
112    @staticmethod
113    def test_jane():

    the terminal is my friend, and shows NameError

    NameError: name 'self' is not defined

GREEN: make it pass

  • I add self to the parentheses of test_joe

    84    @staticmethod
85    # def test_joe():
86    def test_joe(self):
87        first_name = 'joe'
88        last_name = 'blow'
89        sex = 'M'
90        year_of_birth = 1996

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_joe() missing
           1 required positional argument: 'self'

  • I comment out the staticmethod decorator from test_joe

    84    # @staticmethod
85    # def test_joe():
86    def test_joe(self):

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.assert_person_can_say_hello()
           got multiple values for argument 'first_name'

    because a method of an instance takes the instance of the class (self) it belongs to as the first argument.

  • I add self to the parentheses of the assert_person_can_say_hello method of the TestPerson class

    64class TestPerson(unittest.TestCase):
65
66    def assert_person_can_say_hello(
67            # first_name, last_name,
68            self, first_name, last_name,
69            sex, year_of_birth,
70        ):

    the test is green again.

REFACTOR: make it better

  • I change the call to my assert_equal function to the assertNotEqual method of the unittest.TestCase class in the assert_person_can_say_hello method of the TestPerson class

    66    def assert_person_can_say_hello(
67            # first_name, last_name,
68            self,first_name, last_name,
69            sex, year_of_birth,
70        ):
71        # assert_equal(
72        self.assertNotEqual(
73            src.person.Person(
74                first_name=first_name,
75                last_name=last_name,
76                sex=sex,
77                year_of_birth=year_of_birth,
78            ).say_hello(),
79            (
80                f'Hello, my name is {first_name}'
81                f' {last_name} and I am'
82                f' {2026-year_of_birth}.'
83            )
84        )

    the terminal is my friend, and shows AssertionError

    AssertionError: 'Hello, my name is joe blow and I am 30.'
             == 'Hello, my name is joe blow and I am 30.'

  • I change assertNotEqual to assertEqual in the assert_person_can_say_hello method of the TestPerson class

    66    def assert_person_can_say_hello(
67            # first_name, last_name,
68            self,first_name, last_name,
69            sex, year_of_birth,
70        ):
71        # assert_equal(
72        # self.assertNotEqual(
73        self.assertEqual(
74            src.person.Person(
75                first_name=first_name,
76                last_name=last_name,
77                sex=sex,
78                year_of_birth=year_of_birth,
79            ).say_hello(),
80            (
81                f'Hello, my name is {first_name}'
82                f' {last_name} and I am'
83                f' {2026-year_of_birth}.'
84            )
85        )

    the test is green again.

  • I remove the commented lines from the assert_person_can_say_hello method of the TestPerson class

    64class TestPerson(unittest.TestCase):
65
66    def assert_person_can_say_hello(
67            self,first_name, last_name,
68            sex, year_of_birth,
69        ):
70        self.assertEqual(
71            src.person.Person(
72                first_name=first_name,
73                last_name=last_name,
74                sex=sex,
75                year_of_birth=year_of_birth,
76            ).say_hello(),
77            (
78                f'Hello, my name is {first_name}'
79                f' {last_name} and I am'
80                f' {2026-year_of_birth}.'
81            )
82        )
83
84    # @staticmethod
85    # def test_joe():
86    def test_joe(self):

  • I change the call from the assert_person_can_say_hello function to the assert_person_can_say_hello method of the TestPerson class in test_jane

    113    @staticmethod
114    def test_jane():
115        first_name = 'jane'
116        last_name = 'doe'
117        sex = 'F'
118        year_of_birth = 1991
119
120        assert_person_factory_works(
121            first_name=first_name,
122            last_name=last_name,
123            sex=sex,
124            year_of_birth=year_of_birth,
125        )

    127        assert_say_hello_works(
128            first_name=first_name,
129            last_name=last_name,
130            year_of_birth=year_of_birth,
131        )
132
133        # assert_person_can_say_hello(
134        self.assert_person_can_say_hello(
135            first_name=first_name,
136            last_name=last_name,
137            sex=sex,
138            year_of_birth=year_of_birth,
139        )
140
141    @staticmethod
142    def test_john():

    the terminal is my friend, and shows NameError

    NameError: name 'self' is not defined

  • I add self to the parentheses of test_jane

    113    @staticmethod
114    # def test_jane():
115    def test_jane(self):
116        first_name = 'jane'

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_jane() missing
           1 required positional argument: 'self'

  • I comment out the staticmethod decorator from test_jane

    113    # @staticmethod
114    # def test_jane():
115    def test_jane(self):
116        first_name = 'jane'

    the test is green again.

  • I change the call from the assert_person_can_say_hello function to the assert_person_can_say_hello method of the TestPerson class in test_john

    142    @staticmethod
143    def test_john():
144        first_name = 'john'
145        last_name = 'smith'
146        sex = 'M'
147        year_of_birth = 1580
148
149        assert_person_factory_works(
150            first_name=first_name,
151            last_name=last_name,
152            sex=sex,
153            year_of_birth=year_of_birth,
154        )

    156        assert_say_hello_works(
157            first_name=first_name,
158            last_name=last_name,
159            year_of_birth=year_of_birth,
160        )
161
162        # assert_person_can_say_hello(
163        self.assert_person_can_say_hello(
164            first_name=first_name,
165            last_name=last_name,
166            sex=sex,
167            year_of_birth=year_of_birth,
168        )
169
170    @staticmethod
171    def test_mary():

    the terminal is my friend, and shows NameError

    NameError: name 'self' is not defined

  • I add self to the parentheses of test_john

    142    @staticmethod
143    # def test_john():
144    def test_john(self):
145        first_name = 'john'

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_john() missing
           1 required positional argument: 'self'

  • I comment out the staticmethod decorator from test_john

    142    # @staticmethod
143    # def test_john():
144    def test_john(self):
145        first_name = 'john'

    the test is green again.

  • I change the call from the assert_person_can_say_hello function to the assert_person_can_say_hello method of the TestPerson class in test_mary

    171    @staticmethod
172    def test_mary():
173        first_name = 'mary'
174        last_name = 'public'
175        sex = 'F'
176        year_of_birth = 2000
177
178        assert_person_factory_works(
179            first_name=first_name,
180            last_name=last_name,
181            sex=sex,
182            year_of_birth=year_of_birth,
183        )

    185        assert_say_hello_works(
186            first_name=first_name,
187            last_name=last_name,
188            year_of_birth=year_of_birth,
189        )
190
191        # assert_person_can_say_hello(
192        self.assert_person_can_say_hello(
193            first_name=first_name,
194            last_name=last_name,
195            sex=sex,
196            year_of_birth=year_of_birth,
197        )
198
199    def test_dir_person_class(self):

    the terminal is my friend, and shows NameError

    NameError: name 'self' is not defined

  • I add self to the parentheses of test_mary

    171    @staticmethod
172    # def test_mary():
173    def test_mary(self):
174        first_name = 'mary'

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.test_mary() missing
           1 required positional argument: 'self'

  • I comment out the staticmethod decorator from test_mary

    171    # @staticmethod
172    # def test_mary():
173    def test_mary(self):
174        first_name = 'mary'

    green again.

  • I remove the assert_person_can_say_hello function since it is now a repetition

     1import src.person
 2import unittest
 3
 4
 5def assert_equal(left, right):
 6    assert left == right
 7
 8
 9def assert_say_hello_works(
10        first_name, last_name,
11        year_of_birth,
12    ):

    all the tests are still green.

  • I add a git commit message in the other terminal

    git commit -am
'move assert_person_can_say_hello to TestPerson'

move assert_say_hello_works to TestPerson

RED: make it fail

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

  • I add a copy of the assert_say_hello_works function to make it a method of the TestPerson class

    45class TestPerson(unittest.TestCase):
46
47    def assert_say_hello_works(
48            first_name, last_name,
49            year_of_birth,
50        ):
51        assert_equal(
52            src.person.say_hello(
53                first_name=first_name,
54                last_name=last_name,
55                year_of_birth=year_of_birth
56            ),
57            (
58                f'Hello, my name is {first_name}'
59                f' {last_name} and I am'
60                f' {2026-year_of_birth}.'
61            )
62        )
63
64    def assert_person_can_say_hello(
65            self, first_name, last_name,
66            sex, year_of_birth,
67        ):

  • I change the call from the assert_say_hello_works function to the assert_say_hello_works method of the TestPerson class in test_joe

     82    # @staticmethod
 83    # def test_joe():
 84    def test_joe(self):
 85        first_name = 'joe'
 86        last_name = 'blow'
 87        sex = 'M'
 88        year_of_birth = 1996
 89
 90        assert_person_factory_works(
 91            first_name=first_name,
 92            last_name=last_name,
 93            sex=sex,
 94            year_of_birth=year_of_birth
 95        )
 96
 97        # assert_say_hello_works(
 98        self.assert_say_hello_works(
 99            first_name=first_name,
100            last_name=last_name,
101            year_of_birth=year_of_birth,
102        )

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.assert_say_hello_works()
           got multiple values for argument 'first_name'

    because …

GREEN: make it pass

  • I add self to the parentheses of the assert_say_hello_works method of the TestPerson class

    45class TestPerson(unittest.TestCase):
46
47    def assert_say_hello_works(
48            # first_name, last_name,
49            self,first_name, last_name,
50            year_of_birth,
51        ):

    the test is green again.

REFACTOR: make it better

  • I remove the commented line from the assert_say_hello_works method of the TestPerson class

    45class TestPerson(unittest.TestCase):
46
47    def assert_say_hello_works(
48            self,first_name, last_name,
49            year_of_birth,
50        ):

  • I change the call from the assert_say_hello_works function to the assert_say_hello_works method of the TestPerson class in test_jane

    112    # @staticmethod
113    # def test_jane():
114    def test_jane(self):
115        first_name = 'jane'
116        last_name = 'doe'
117        sex = 'F'
118        year_of_birth = 1991
119
120        assert_person_factory_works(
121            first_name=first_name,
122            last_name=last_name,
123            sex=sex,
124            year_of_birth=year_of_birth,
125        )
126
127        # assert_say_hello_works(
128        self.assert_say_hello_works(
129            first_name=first_name,
130            last_name=last_name,
131            year_of_birth=year_of_birth,
132        )

    the test is still green.

  • I change the call from the assert_say_hello_works function to the assert_say_hello_works method of the TestPerson class in test_john

    142    # @staticmethod
143    # def test_john():
144    def test_john(self):
145        first_name = 'john'
146        last_name = 'smith'
147        sex = 'M'
148        year_of_birth = 1580
149
150        assert_person_factory_works(
151            first_name=first_name,
152            last_name=last_name,
153            sex=sex,
154            year_of_birth=year_of_birth,
155        )
156
157        # assert_say_hello_works(
158        self.assert_say_hello_works(
159            first_name=first_name,
160            last_name=last_name,
161            year_of_birth=year_of_birth,
162        )

    still green.

  • I change the call from the assert_say_hello_works function to the assert_say_hello_works method of the TestPerson class in test_mary

    172    # @staticmethod
173    # def test_mary():
174    def test_mary(self):
175        first_name = 'mary'
176        last_name = 'public'
177        sex = 'F'
178        year_of_birth = 2000
179
180        assert_person_factory_works(
181            first_name=first_name,
182            last_name=last_name,
183            sex=sex,
184            year_of_birth=year_of_birth,
185        )
186
187        # assert_say_hello_works(
188        self.assert_say_hello_works(
189            first_name=first_name,
190            last_name=last_name,
191            year_of_birth=year_of_birth,
192        )

    green.

  • I change the call to my assert_equal function to the assertNotEqual method of the unittest.TestCase class in the assert_say_hello_works method of the TestPerson class

    47    def assert_say_hello_works(
48            self, first_name, last_name,
49            year_of_birth,
50        ):
51        # assert_equal(
52        self.assertNotEqual(
53            src.person.say_hello(
54                first_name=first_name,
55                last_name=last_name,
56                year_of_birth=year_of_birth
57            ),
58            (
59                f'Hello, my name is {first_name}'
60                f' {last_name} and I am'
61                f' {2026-year_of_birth}.'
62            )
63        )

    the terminal is my friend, and shows AssertionError

    FAILED ...test_jane - AssertionError:
    'Hello, my name is jane doe and I am 35.'
 == 'Hello, my name is jane doe and I am 35.'
FAILED ...test_joe - AssertionError:
    'Hello, my name is joe blow and I am 30.'
 == 'Hello, my name is joe blow and I am 30.'
FAILED ...test_john - AssertionError:
    'Hello, my name is john smith and I am 446.'
 == 'Hello, my name is john smith and I am 446.'
FAILED ...test_mary - AssertionError:
    'Hello, my name is mary public and I am 26.'
 == 'Hello, my name is mary public and I am 26.'

  • I change assertNotEqual to assertEqual in the assert_say_hello_works method of the TestPerson class

    47    def assert_say_hello_works(
48            self, first_name, last_name,
49            year_of_birth,
50        ):
51        # assert_equal(
52        # self.assertNotEqual(
53        self.assertEqual(
54            src.person.say_hello(
55                first_name=first_name,
56                last_name=last_name,
57                year_of_birth=year_of_birth
58            ),
59            (
60                f'Hello, my name is {first_name}'
61                f' {last_name} and I am'
62                f' {2026-year_of_birth}.'
63            )
64        )

    the test is green again.

  • I remove the commented lines from the assert_say_hello_works method of the TestPerson class

    47    def assert_say_hello_works(
48            self, first_name, last_name,
49            year_of_birth,
50        ):
51        self.assertEqual(
52            src.person.say_hello(
53                first_name=first_name,
54                last_name=last_name,
55                year_of_birth=year_of_birth
56            ),
57            (
58                f'Hello, my name is {first_name}'
59                f' {last_name} and I am'
60                f' {2026-year_of_birth}.'
61            )
62        )
63
64    def assert_person_can_say_hello(

  • I remove the assert_say_hello_works function since it is now a repetition

     1import src.person
 2import unittest
 3
 4
 5def assert_equal(left, right):
 6    assert left == right
 7
 8
 9def assert_person_factory_works(
10        first_name, last_name,
11        sex, year_of_birth
12    ):

    the tests are still green.

  • I add a git commit message in the other terminal

    git commit -am
'move assert_say_hello_works to TestPerson'

move assert_person_factory_works to TestPerson

RED: make it fail

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

  • I add a copy of the assert_person_factory_works function to make it a method of the TestPerson class

    27class TestPerson(unittest.TestCase):
28
29    def assert_person_factory_works(
30            first_name, last_name,
31            sex, year_of_birth
32        ):
33        assert_equal(
34            src.person.person(
35                first_name=first_name,
36                last_name=last_name,
37                sex=sex,
38                year_of_birth=year_of_birth,
39            ),
40            (
41                f'{first_name}, {last_name},'
42                f' {sex}, {year_of_birth}'
43            )
44        )
45
46    def assert_say_hello_works(
47            self, first_name, last_name,
48            year_of_birth,
49        ):

  • I change the call from the assert_person_factory_works function to the assert_person_factory_works method of the TestPerson class in test_joe

    81    # @staticmethod
82    # def test_joe():
83    def test_joe(self):
84        first_name = 'joe'
85        last_name = 'blow'
86        sex = 'M'
87        year_of_birth = 1996
88
89        # assert_person_factory_works(
90        self.assert_person_factory_works(
91            first_name=first_name,
92            last_name=last_name,
93            sex=sex,
94            year_of_birth=year_of_birth
95        )

    the terminal is my friend, and shows TypeError

    TypeError: TestPerson.assert_person_factory_works()
           got multiple values for argument 'first_name'

GREEN: make it pass

REFACTOR: make it better

  • I remove the commented line from the assert_person_factory_works method of the TestPerson class

    27class TestPerson(unittest.TestCase):
28
29    def assert_person_factory_works(
30            self, first_name, last_name,
31            sex, year_of_birth
32        ):

  • I remove the commented lines from test_joe

    63    def assert_person_can_say_hello(
64            self,first_name, last_name,
65            sex, year_of_birth,
66        ):
67        self.assertEqual(
68            src.person.Person(
69                first_name=first_name,
70                last_name=last_name,
71                sex=sex,
72                year_of_birth=year_of_birth,
73            ).say_hello(),
74            (
75                f'Hello, my name is {first_name}'
76                f' {last_name} and I am'
77                f' {2026-year_of_birth}.'
78            )
79        )

    81    def test_joe(self):
82        first_name = 'joe'
83        last_name = 'blow'
84        sex = 'M'
85        year_of_birth = 1996
86
87        self.assert_person_factory_works(
88            first_name=first_name,
89            last_name=last_name,
90            sex=sex,
91            year_of_birth=year_of_birth
92        )

     94        self.assert_say_hello_works(
 95            first_name=first_name,
 96            last_name=last_name,
 97            year_of_birth=year_of_birth,
 98        )
 99
100        self.assert_person_can_say_hello(
101            first_name=first_name,
102            last_name=last_name,
103            sex=sex,
104            year_of_birth=year_of_birth
105        )
106
107    # @staticmethod
108    # def test_jane():
109    def test_jane(self):

  • I change the call from the assert_person_factory_works function to the assert_person_factory_works method of the TestPerson class in test_jane

    107    # @staticmethod
108    # def test_jane():
109    def test_jane(self):
110        first_name = 'jane'
111        last_name = 'doe'
112        sex = 'F'
113        year_of_birth = 1991
114
115        # assert_person_factory_works(
116        self.assert_person_factory_works(
117            first_name=first_name,
118            last_name=last_name,
119            sex=sex,
120            year_of_birth=year_of_birth,
121        )

    still green.

  • I remove the commented lines from test_jane

    100        self.assert_person_can_say_hello(
101            first_name=first_name,
102            last_name=last_name,
103            sex=sex,
104            year_of_birth=year_of_birth
105        )
106
107    def test_jane(self):
108        first_name = 'jane'
109        last_name = 'doe'
110        sex = 'F'
111        year_of_birth = 1991
112
113        self.assert_person_factory_works(
114            first_name=first_name,
115            last_name=last_name,
116            sex=sex,
117            year_of_birth=year_of_birth,
118        )

    120        self.assert_say_hello_works(
121            first_name=first_name,
122            last_name=last_name,
123            year_of_birth=year_of_birth,
124        )
125
126        self.assert_person_can_say_hello(
127            first_name=first_name,
128            last_name=last_name,
129            sex=sex,
130            year_of_birth=year_of_birth,
131        )
132
133    # @staticmethod
134    # def test_john():
135    def test_john(self):

  • I change the call from the assert_person_factory_works function to the assert_person_factory_works method of the TestPerson class in test_john

    133    # @staticmethod
134    # def test_john():
135    def test_john(self):
136        first_name = 'john'
137        last_name = 'smith'
138        sex = 'M'
139        year_of_birth = 1580
140
141        # assert_person_factory_works(
142        self.assert_person_factory_works(
143            first_name=first_name,
144            last_name=last_name,
145            sex=sex,
146            year_of_birth=year_of_birth,
147        )

    the test is still green.

  • I remove the commented lines from test_john

    126        self.assert_person_can_say_hello(
127            first_name=first_name,
128            last_name=last_name,
129            sex=sex,
130            year_of_birth=year_of_birth,
131        )
132
133    def test_john(self):
134        first_name = 'john'
135        last_name = 'smith'
136        sex = 'M'
137        year_of_birth = 1580
138
139        self.assert_person_factory_works(
140            first_name=first_name,
141            last_name=last_name,
142            sex=sex,
143            year_of_birth=year_of_birth,
144        )

    146        self.assert_say_hello_works(
147            first_name=first_name,
148            last_name=last_name,
149            year_of_birth=year_of_birth,
150        )
151
152        self.assert_person_can_say_hello(
153            first_name=first_name,
154            last_name=last_name,
155            sex=sex,
156            year_of_birth=year_of_birth,
157        )
158
159    # @staticmethod
160    # def test_mary():
161    def test_mary(self):

  • I change the call from the assert_person_factory_works function to the assert_person_factory_works method of the TestPerson class in test_mary

    159    # @staticmethod
160    # def test_mary():
161    def test_mary(self):
162        first_name = 'mary'
163        last_name = 'public'
164        sex = 'F'
165        year_of_birth = 2000
166
167        # assert_person_factory_works(
168        self.assert_person_factory_works(
169            first_name=first_name,
170            last_name=last_name,
171            sex=sex,
172            year_of_birth=year_of_birth,
173        )

    green.

  • I remove the commented lines from test_mary

    152        self.assert_person_can_say_hello(
153            first_name=first_name,
154            last_name=last_name,
155            sex=sex,
156            year_of_birth=year_of_birth,
157        )
158
159    def test_mary(self):
160        first_name = 'mary'
161        last_name = 'public'
162        sex = 'F'
163        year_of_birth = 2000
164
165        self.assert_person_factory_works(
166            first_name=first_name,
167            last_name=last_name,
168            sex=sex,
169            year_of_birth=year_of_birth,
170        )

    172        self.assert_say_hello_works(
173            first_name=first_name,
174            last_name=last_name,
175            year_of_birth=year_of_birth,
176        )
177
178        self.assert_person_can_say_hello(
179            first_name=first_name,
180            last_name=last_name,
181            sex=sex,
182            year_of_birth=year_of_birth,
183        )
184
185    def test_dir_person_class(self):

  • I change the call to my assert_equal function to the assertNotEqual method of the unittest.TestCase class in the assert_person_factory_works method of the TestPerson class

    29    def assert_person_factory_works(
30            self, first_name, last_name,
31            sex, year_of_birth
32        ):
33        # assert_equal(
34        self.assertNotEqual(
35            src.person.person(
36                first_name=first_name,
37                last_name=last_name,
38                sex=sex,
39                year_of_birth=year_of_birth,
40            ),
41            (
42                f'{first_name}, {last_name},'
43                f' {sex}, {year_of_birth}'
44            )
45        )

    the terminal is my friend, and shows AssertionError

    FAILED ...test_jane - AssertionError:
    'jane, doe, F, 1991' == 'jane, doe, F, 1991'
FAILED ...test_joe - AssertionError:
    'joe, blow, M, 1996' == 'joe, blow, M, 1996'
FAILED ...test_john - AssertionError:
    'john, smith, M, 1580' == 'john, smith, M, 1580'
FAILED ...test_mary - AssertionError:
    'mary, public, F, 2000' == 'mary, public, F, 2000'

  • I change assertNotEqual to assertEqual in the assert_person_factory_works method of the TestPerson class

    29    def assert_person_factory_works(
30            self, first_name, last_name,
31            sex, year_of_birth
32        ):
33        # assert_equal(
34        # self.assertNotEqual(
35        self.assertEqual(
36            src.person.person(
37                first_name=first_name,
38                last_name=last_name,
39                sex=sex,
40                year_of_birth=year_of_birth,
41            ),
42            (
43                f'{first_name}, {last_name},'
44                f' {sex}, {year_of_birth}'
45            )
46        )

    the test is green again.

  • I remove the commented lines from the assert_person_factory_works method of the TestPerson class

    27class TestPerson(unittest.TestCase):
28
29    def assert_person_factory_works(
30            self, first_name, last_name,
31            sex, year_of_birth
32        ):
33        self.assertEqual(
34            src.person.person(
35                first_name=first_name,
36                last_name=last_name,
37                sex=sex,
38                year_of_birth=year_of_birth,
39            ),
40            (
41                f'{first_name}, {last_name},'
42                f' {sex}, {year_of_birth}'
43            )
44        )

  • I remove the assert_person_factory_works function since it is now a repetition and my assert_equal function since it is no longer used

    1import src.person
2import unittest
3
4
5class TestPerson(unittest.TestCase):

    green.

  • I add a git commit message in the other terminal

    git commit -am
'move assert_person_factory_works to TestPerson'

close the project

  • I close test_person.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 person

    cd ..

    the terminal shows

    ...\pumping_python

    I am back in the pumping_python directory.

review

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