booleans 1

There are only 2 booleans - True and False. I can use the assertFalse and assertTrue methods to test if any of the Python basic data structures seen so far - None, integers, floats, strings, tuples, lists, sets and dictionaries, are False or True.

preview

These are the tests I have by the end of the chapter

 1import unittest
 2
 3
 4class TestBooleans(unittest.TestCase):
 5
 6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(0.0)
12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse(set())
16        self.assertFalse(dict())
17
18    def test_what_is_true(self):
19        self.assertIsInstance(True, bool)
20        self.assertTrue(True)
21        self.assertTrue(-1)
22        self.assertTrue(1)
23        self.assertTrue(-0.1)
24        self.assertTrue(0.1)
25        self.assertTrue("text")
26        self.assertTrue((1, 2, 3, 'n'))
27        self.assertTrue([1, 2, 3, 'n'])
28        self.assertTrue({1, 2, 3, 'n'})
29        self.assertTrue({'key': 'value'})
30
31
32# NOTES
33# a dictionary with things is True
34# a set with things is True
35# a list with things is True
36# a tuple with things is True
37# a string with things is True
38# positive and negative numbers are True
39# True is True
40# True is not false
41# True is a boolean
42# the empty dictionary is False
43# the empty set is False
44# the empty list is False
45# the empty tuple is False
46# the empty string is False
47# 0 is False
48# None is False
49# False is False
50# False is not true
51# False is a boolean
52
53
54# Exceptions seen
55# AssertionError

questions about Booleans

Here are questions you can answer after going through this chapter

start the project

  • I name this project booleans

  • I open a terminal

  • I make a directory for the project

    mkdir booleans

  • I change directory to the project

    cd booleans

    the terminal shows I am in the booleans folder

    .../pumping_python/booleans

  • I make a directory for the tests

    mkdir tests

  • 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

    Note

    on Windows without Windows Subsystem for Linux use New-Item tests/__init__.py instead of touch tests/__init__.py

    New-Item tests/__init__.py

  • I make a Python file for the tests in the tests directory

    touch tests/test_booleans.py

    Note

    on Windows without Windows Subsystem for Linux use New-Item tests/test_booleans.py instead of touch tests/test_booleans.py

    New-Item tests/test_booleans.py

  • I open test_booleans.py in the editor of the Integrated Development Environment (IDE)

    Tip

    I can use the terminal to open a file in the Integrated Development Environment (IDE) by typing the name of the program and the name of the file. That means when I type this in the terminal

    code tests/test_booleans.py

    Visual Studio Code opens test_booleans.py in the editor

  • I add the first failing test to test_booleans.py

    1import unittest
2
3
4class TestBooleans(unittest.TestCase):
5
6    def test_failure(self):
7        self.assertFalse(True)

  • I make a requirements file for the Python packages I need, in the terminal

    echo "pytest" > requirements.txt

  • I add pytest-watcher to the file

    echo "pytest-watcher" >> requirements.txt

  • I setup the project with uv

    uv init

    the terminal shows

    Initialized project `booleans`

  • I remove main.py from the project because I do not use it

    rm main.py

  • I install the Python packages I gave in the requirements file

    uv add --requirement requirements.txt

  • I use pytest-watcher to run the tests automatically

    uv run pytest-watcher . --now

    the terminal shows

    ================================ FAILURES ================================
_______________________ TestBooleans.test_failure ________________________

self = <tests.test_booleans.TestBooleans testMethod=test_failure>

    def test_failure(self):
>       self.assertFalse(True)
E       AssertionError: True is not false

tests/test_booleans.py:7: AssertionError
======================== short test summary info =========================
FAILED tests/test_booleans.py::TestBooleans::test_failure - AssertionError: True is not false
=========================== 1 failed in X.YZs ============================

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

     4class TestBooleans(unittest.TestCase):
 5
 6    def test_failure(self):
 7        self.assertFalse(True)
 8
 9
10# Exceptions seen
11# AssertionError

  • then I change True to False in the assertion

    7        self.assertFalse(False)

    the test passes

test_what_is_false

RED: make it fail

  • I change test_failure to test_what_is_false, then use the assertNotIsInstance method I learned from testing None to check if False is a child (instance) of the bool class. I think this will fail

     1import unittest
 2
 3
 4class TestBooleans(unittest.TestCase):
 5
 6    def test_what_is_false(self):
 7        self.assertNotIsInstance(False, bool)
 8
 9
10# Exceptions seen
11# AssertionError

    the terminal shows AssertionError

    AssertionError: False is an instance of <class 'bool'>

  • I add comments

     4class TestBooleans(unittest.TestCase):
 5
 6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8
 9
10# NOTES
11# False is a boolean
12
13
14# Exceptions seen
15# AssertionError

    so far this is something I already know from testing None

GREEN: make it pass

I change assertNotIsInstance to assertIsInstance

7        self.assertIsInstance(False, bool)

the test passes

False is a boolean

test_what_is_true

I do the same thing with True

RED: make it fail

  • I add another failing test

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8
 9    def test_what_is_true(self):
10        self.assertNotIsInstance(True, bool)
11
12
13# NOTES

    the terminal shows AssertionError

    AssertionError: True is an instance of <class 'bool'>

  • I add a comment

    13# NOTES
14# True is a boolean
15# False is a boolean
16
17
18# Exceptions seen
19# AssertionError

GREEN: make it pass

I change the assert method

 9    def test_what_is_true(self):
10        self.assertIsInstance(True, bool)
11
12
13# NOTES

the test passes

True is a boolean

REFACTOR: make it better

  • I add a line that will fail to the test_what_is_true method

     9    def test_what_is_true(self):
10        self.assertIsInstance(True, bool)
11        self.assertTrue(False)
12
13
14# NOTES

    the terminal shows AssertionError

    AssertionError: False is not true

  • I add a comment

    14# NOTES
15# True is a boolean
16# False is not true
17# False is a boolean
18
19
20# Exceptions seen
21# AssertionError

  • I change assertTrue to assertFalse

     9    def test_what_is_true(self):
10        self.assertIsInstance(True, bool)
11        self.assertFalse(False)
12
13
14# NOTES

    the test passes

  • I add a comment

    14# NOTES
15# True is a boolean
16# False is False
17# False is not true
18# False is a boolean
19
20
21# Exceptions seen

  • I move the assertion from test_what_is_true to the test_what_is_false method

    Tip

    In Visual Studio Code I can use alt (Windows/Linux) or option (MacOS) with the up/down arrows on the keyboard to move a line up or down

     4class TestBooleans(unittest.TestCase):
 5
 6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9
10    def test_what_is_true(self):
11        self.assertIsInstance(True, bool)
12
13
14# NOTES

  • I add a line that will fail to the test_what_is_false method

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(True)
10
11    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: True is not false

  • I add a comment

    15# NOTES
16# True is not false
17# True is a boolean
18# False is False
19# False is not true
20# False is a boolean
21
22
23# Exceptions seen

  • I change assertFalse to assertTrue

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertTrue(True)
10
11    def test_what_is_true(self):
12        self.assertIsInstance(True, bool)
13
14
15# NOTES

    the test passes

  • I add a comment

    15# NOTES
16# True is True
17# True is not false
18# True is a boolean
19# False is False
20# False is not true
21# False is a boolean
22
23
24# Exceptions seen
25# AssertionError

  • I move the assertion from test_what_is_false to the test_what_is_true method

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9
10    def test_what_is_true(self):
11        self.assertIsInstance(True, bool)
12        self.assertTrue(True)
13
14
15# NOTES

All of these are still statements from the AssertionError and None chapters.

Next up, I test the other Python basic data structures to see which ones are False or True. What do you think?

is None False or True?

RED: make it fail

I add an assertion to test_what_is_true to test if None is True

10    def test_what_is_true(self):
11        self.assertIsInstance(True, bool)
12        self.assertTrue(True)
13        self.assertTrue(None)
14
15
16# NOTES

the terminal shows AssertionError

AssertionError: None is not true

GREEN: make it pass

I change the method

13        self.assertFalse(None)

the test passes

REFACTOR: make it better

  • I add a comment

    16# NOTES
17# True is True
18# True is not false
19# True is a boolean
20# None is False
21# False is False
22# False is not true
23# False is a boolean
24
25
26# Exceptions seen

  • I move the assertion from test_what_is_true to test_what_is_false

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10
11    def test_what_is_true(self):
12        self.assertIsInstance(True, bool)
13        self.assertTrue(True)
14
15
16# NOTES

None is False and I learned from the AssertionError chapter that False is not None

is an integer False or True?

RED: make it fail

I add a line that will fail to the test_what_is_false method to see if an integer (a whole number) is False

 6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(-1)
11
12    def test_what_is_true(self):

the terminal shows AssertionError

AssertionError: -1 is not false

I use -1 for all the integers (whole numbers) that are smaller than 0

GREEN: make it pass

I change the method

10        self.assertTrue(-1)

the test passes

REFACTOR: make it better

  • I add a comment

    19# NOTES
20# negative integers are True
21# True is True
22# True is not false
23# True is a boolean
24# None is False
25# False is False
26# False is not true
27# False is a boolean

  • I move the assertion from test_what_is_false to test_what_is_true

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10
11    def test_what_is_true(self):
12        self.assertIsInstance(True, bool)
13        self.assertTrue(True)
14        self.assertTrue(-1)
15
16
17# NOTES

    negative integers are True in Python

  • I add a new failing line to test_what_is_true to see if 0 is True

    11    def test_what_is_true(self):
12        self.assertIsInstance(True, bool)
13        self.assertTrue(True)
14        self.assertTrue(-1)
15        self.assertTrue(0)
16
17
18# NOTES

    the terminal shows AssertionError

    AssertionError: 0 is not true

  • I change the method to assertFalse

    15        self.assertFalse(0)

    the test passes

  • I add a comment

    18# NOTES
19# negative integers are True
20# True is True
21# True is not false
22# True is a boolean
23# 0 is False
24# None is False
25# False is False
26# False is not true
27# False is a boolean

  • I move the assertion to test_what_is_false

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11
12    def test_what_is_true(self):

    0 is False in Python

  • I add another failing line to test_what_is_false to see if 1 is False

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(1)
12
13    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: 1 is not false

    I use 1 for all the integers (whole numbers) that are bigger than 0

  • I change the method

    11        self.assertTrue(1)

    the test passes

  • I add to the comment about negative integers

    19# NOTES
20# positive and negative integers are True
21# True is True
22# True is not false
23# True is a boolean
24# 0 is False
25# None is False
26# False is False
27# False is not true
28# False is a boolean

  • I move the assertion to test_what_is_true

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11
12    def test_what_is_true(self):
13        self.assertIsInstance(True, bool)
14        self.assertTrue(True)
15        self.assertTrue(-1)
16        self.assertTrue(1)
17
18
19# NOTES

in Python 0 is False, and positive and negative integers are True

is a float False or True?

RED: make it fail

I add an assertion to test if floats (binary floating point decimal numbers) are False in test_what_is_false

 6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(-0.1)
12
13    def test_what_is_true(self):

the terminal shows AssertionError

AssertionError: -0.1 is not false

I use -0.1 for all the binary floating point numbers that are smaller than 0.0.

GREEN: make it pass

  • I change the method

    11        self.assertTrue(-0.1)

    the test passes

  • I add comments

    20# NOTES
21# negative floats are True
22# positive and negative integers are True
23# True is True
24# True is not false
25# True is a boolean
26# 0 is False
27# None is False
28# False is False
29# False is not true
30# False is a boolean

  • I move the assertion to test_what_is_true

     9        self.assertFalse(None)
10        self.assertFalse(0)
11
12    def test_what_is_true(self):
13        self.assertIsInstance(True, bool)
14        self.assertTrue(True)
15        self.assertTrue(-1)
16        self.assertTrue(1)
17        self.assertTrue(-0.1)
18
19
20# NOTES

Negative floats are True in Python

REFACTOR: make it better

  • I add another failing line to test_what_is_true to see if 0.0 is True

    12    def test_what_is_true(self):
13        self.assertIsInstance(True, bool)
14        self.assertTrue(True)
15        self.assertTrue(-1)
16        self.assertTrue(1)
17        self.assertTrue(-0.1)
18        self.assertTrue(0.0)
19
20
21# NOTES

    the terminal shows AssertionError

    AssertionError: 0.0 is not true

  • I change the method

    18        self.assertFalse(0.0)

    the test passes

  • I add a comment

    21# NOTES
22# negative floats are True
23# positive and negative integers are True
24# True is True
25# True is not false
26# True is a boolean
27# 0.0 is False
28# 0 is False
29# None is False
30# False is False
31# False is not true
32# False is a boolean

  • I move the assertion to test_what_is_false

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(0.0)
12
13    def test_what_is_true(self):

    0.0 is False in Python

  • I add another assertion to test_what_is_false to see if 0.1 is False

    10        self.assertFalse(0)
11        self.assertFalse(0.0)
12        self.assertFalse(0.1)
13
14    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: 0.1 is not false

    I use 0.1 for all the binary floating point numbers that are bigger than 0.0.

  • I change the method

    12        self.assertTrue(0.1)

    the test passes

  • I add to the comment about negative floats

    22# NOTES
23# positive and negative floats are True
24# positive and negative integers are True
25# True is True
26# True is not false
27# True is a boolean
28# 0.0 is False
29# 0 is False
30# None is False
31# False is False
32# False is not true
33# False is a boolean

  • I move the assertion to test_what_is_true

    10        self.assertFalse(0)
11        self.assertFalse(0.0)
12
13    def test_what_is_true(self):
14        self.assertIsInstance(True, bool)
15        self.assertTrue(True)
16        self.assertTrue(-1)
17        self.assertTrue(1)
18        self.assertTrue(-0.1)
19        self.assertTrue(0.1)
20
21
22# NOTES

  • I make the new comments simpler because floats and integers are numbers and 0.0 is the same as 0 even though they are different types

    22# NOTES
23# positive and negative numbers are True
24# True is True
25# True is not false
26# True is a boolean
27# 0 is False
28# None is False
29# False is False
30# False is not true
31# False is a boolean

in Python, 0.0 is False and positive and negative floats are True

is a string False or True?

RED: make it fail

I add a line that will fail to test_what_is_true to test if a string (anything in quotes) is True

13    def test_what_is_true(self):
14        self.assertIsInstance(True, bool)
15        self.assertTrue(True)
16        self.assertTrue(-1)
17        self.assertTrue(1)
18        self.assertTrue(-0.1)
19        self.assertTrue(0.1)
20        self.assertTrue(str())
21
22
23# NOTES

the terminal shows AssertionError

AssertionError: '' is not true

the empty string (‘’) is not True

GREEN: make it pass

I change the method

20        self.assertFalse(str())

the test passes

REFACTOR: make it better

  • I add a comment

    23# NOTES
24# positive and negative numbers are True
25# True is True
26# True is not false
27# True is a boolean
28# the empty string is False
29# 0 is False
30# None is False
31# False is False
32# False is not true
33# False is a boolean

  • I move the assertion to test_what_is_false

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(0.0)
12        self.assertFalse(str())
13
14    def test_what_is_true(self):

  • I add a line that will fail to test_what_is_false

    11        self.assertFalse(0.0)
12        self.assertFalse(str())
13        self.assertFalse("text")

    the terminal shows AssertionError

    AssertionError: 'text' is not false

  • I change the method

    13        self.assertTrue("text")

    the test passes

  • I add a comment

    24# NOTES
25# a string with things is True
26# positive and negative numbers are True
27# True is True
28# True is not false
29# True is a boolean
30# the empty string is False
31# 0 is False
32# None is False
33# False is False
34# False is not true
35# False is a boolean

  • I move the assertion to test_what_is_true

    11        self.assertFalse(0.0)
12        self.assertFalse(str())
13
14    def test_what_is_true(self):
15        self.assertIsInstance(True, bool)
16        self.assertTrue(True)
17        self.assertTrue(-1)
18        self.assertTrue(1)
19        self.assertTrue(-0.1)
20        self.assertTrue(0.1)
21        self.assertTrue("text")
22
23
24# NOTES

in Python, the empty string is False and a string with things is True

is a tuple False or True?

RED: make it fail

I add an assertion to test_what_is_true to see if a tuple (anything in parentheses (()) separated by commas) is True

14    def test_what_is_true(self):
15        self.assertIsInstance(True, bool)
16        self.assertTrue(True)
17        self.assertTrue(-1)
18        self.assertTrue(1)
19        self.assertTrue(-0.1)
20        self.assertTrue(0.1)
21        self.assertTrue("text")
22        self.assertTrue(tuple())
23
24
25# NOTES

The terminal shows AssertionError

AssertionError: () is not true

the empty tuple is not True

GREEN: make it pass

  • I change the assert method

    22        self.assertFalse(tuple())

    the test passes

  • I add a comment

    25# NOTES
26# a string with things is True
27# positive and negative numbers are True
28# True is True
29# True is not false
30# True is a boolean
31# the empty tuple is False
32# the empty string is False
33# 0 is False
34# None is False
35# False is False
36# False is not true
37# False is a boolean

  • I move the assertion to test_what_is_false

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(0.0)
12        self.assertFalse(str())
13        self.assertFalse(tuple())
14
15    def test_what_is_true(self):

REFACTOR: make it better

  • I add another assertion to test_what_is_false to see if a tuple with things is False

    11        self.assertFalse(0.0)
12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse((1, 2, 3, 'n'))
15
16    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: (1, 2, 3, 'n') is not false

    a tuple with things is NOT False

  • I change the method

    14        self.assertTrue((1, 2, 3, 'n'))

    the test passes

  • I add a comment

    26# NOTES
27# a tuple with things is True
28# a string with things is True
29# positive and negative numbers are True
30# True is True
31# True is not false
32# True is a boolean
33# the empty tuple is False
34# the empty string is False
35# 0 is False
36# None is False
37# False is False
38# False is not true
39# False is a boolean

  • I move the assertion to test_what_is_true

    Tip

    In Visual Studio Code I can use alt (Windows/Linux) or option (MacOS) with the up/down arrows on the keyboard to move a line up or down

    12        self.assertFalse(str())
13        self.assertFalse(tuple())
14
15    def test_what_is_true(self):
16        self.assertIsInstance(True, bool)
17        self.assertTrue(True)
18        self.assertTrue(-1)
19        self.assertTrue(1)
20        self.assertTrue(-0.1)
21        self.assertTrue(0.1)
22        self.assertTrue("text")
23        self.assertTrue((1, 2, 3, 'n'))
24
25
26# NOTES

in Python, the empty tuple is False and a tuple with things is True

is a list False or True?

RED: make it fail

I add an assertion to test if a list (anything in square brackets ([])) is True

15    def test_what_is_true(self):
16        self.assertIsInstance(True, bool)
17        self.assertTrue(True)
18        self.assertTrue(-1)
19        self.assertTrue(1)
20        self.assertTrue(-0.1)
21        self.assertTrue(0.1)
22        self.assertTrue("text")
23        self.assertTrue((1, 2, 3, 'n'))
24        self.assertTrue(list())
25
26
27# NOTES

the terminal shows AssertionError

AssertionError: [] is not true

the empty list is NOT True

GREEN: make it pass

  • I change the method

    24        self.assertFalse(list())

    the test passes

  • I add a comment

    27# NOTES
28# a tuple with things is True
29# a string with things is True
30# positive and negative numbers are True
31# True is True
32# True is not false
33# True is a boolean
34# the empty list is False
35# the empty tuple is False
36# the empty string is False
37# 0 is False
38# None is False
39# False is False
40# False is not true
41# False is a boolean

  • I move the assertion to test_what_is_false

    12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15
16    def test_what_is_true(self):

REFACTOR: make it better

  • I add another assertion to test_what_is_false to see if a list with things is False

    12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse([1, 2, 3, 'n'])
16
17    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: [1, 2, 3, 'n'] is not false

  • I change the method

    15        self.assertTrue([1, 2, 3, 'n'])

    the test passes

  • I add a comment

    28# NOTES
29# a list with things is True
30# a tuple with things is True
31# a string with things is True
32# positive and negative numbers are True
33# True is True
34# True is not false
35# True is a boolean
36# the empty list is False
37# the empty tuple is False
38# the empty string is False
39# 0 is False
40# None is False
41# False is False
42# False is not true
43# False is a boolean

  • I move the assertion to test_what_is_true

    13        self.assertFalse(tuple())
14        self.assertFalse(list())
15
16    def test_what_is_true(self):
17        self.assertIsInstance(True, bool)
18        self.assertTrue(True)
19        self.assertTrue(-1)
20        self.assertTrue(1)
21        self.assertTrue(-0.1)
22        self.assertTrue(0.1)
23        self.assertTrue("text")
24        self.assertTrue((1, 2, 3, 'n'))
25        self.assertTrue([1, 2, 3, 'n'])
26
27
28# NOTES

in Python, the empty list is False and a list with things is True. I can see a pattern.

is a set False or True?

RED: make it fail

I add an assertion to test_what_is_true to see if a set is True

23        self.assertTrue("text")
24        self.assertTrue((1, 2, 3, 'n'))
25        self.assertTrue([1, 2, 3, 'n'])
26        self.assertTrue(set())
27
28
29# NOTES

the terminal shows AssertionError

AssertionError: set() is not true

the empty set is NOT True

GREEN: make it pass

  • I change the method

    26        self.assertFalse(set())

    the test passes

  • I add a comment

    29# NOTES
30# a list with things is True
31# a tuple with things is True
32# a string with things is True
33# positive and negative numbers are True
34# True is True
35# True is not false
36# True is a boolean
37# the empty set is False
38# the empty list is False
39# the empty tuple is False
40# the empty string is False
41# 0 is False
42# None is False
43# False is False
44# False is not true
45# False is a boolean

  • I move the assertion to test_what_is_false

    12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse(set())
16
17    def test_what_is_true(self):

REFACTOR: make it better

  • I add another assertion to test_what_is_false to see if a set with things is False

    12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse(set())
16        self.assertFalse({1, 2, 3, 'n'})
17
18    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: {1, 2, 3, 'n'} is not false

    a set with things is NOT False

  • I change the method

    16        self.assertTrue({1, 2, 3, 'n'})

    the test passes

  • I add a comment

    30# NOTES
31# a set with things is True
32# a list with things is True
33# a tuple with things is True
34# a string with things is True
35# positive and negative numbers are True
36# True is True
37# True is not false
38# True is a boolean
39# the empty set is False
40# the empty list is False
41# the empty tuple is False
42# the empty string is False
43# 0 is False
44# None is False
45# False is False
46# False is not true
47# False is a boolean

  • I move the assertion to test_what_is_true

    13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse(set())
16
17    def test_what_is_true(self):
18        self.assertIsInstance(True, bool)
19        self.assertTrue(True)
20        self.assertTrue(-1)
21        self.assertTrue(1)
22        self.assertTrue(-0.1)
23        self.assertTrue(0.1)
24        self.assertTrue("text")
25        self.assertTrue((1, 2, 3, 'n'))
26        self.assertTrue([1, 2, 3, 'n'])
27        self.assertTrue({1, 2, 3, 'n'})
28
29
30# NOTES

in Python, the empty set is False and a set with things is True

is a dictionary False or True?

RED: make it fail

I add an assertion to test_what_is_true to test if a dictionary is True

17    def test_what_is_true(self):
18        self.assertIsInstance(True, bool)
19        self.assertTrue(True)
20        self.assertTrue(-1)
21        self.assertTrue(1)
22        self.assertTrue(-0.1)
23        self.assertTrue(0.1)
24        self.assertTrue("text")
25        self.assertTrue((1, 2, 3, 'n'))
26        self.assertTrue([1, 2, 3, 'n'])
27        self.assertTrue({1, 2, 3, 'n'})
28        self.assertTrue(dict())
29
30
31# NOTES

the terminal shows AssertionError

AssertionError: {} is not true

the empty dictionary is NOT True

GREEN: make it pass

  • I change assertTrue to assertFalse

    28        self.assertFalse(dict())

    the test passes

  • I add a comment

    31# NOTES
32# a set with things is True
33# a list with things is True
34# a tuple with things is True
35# a string with things is True
36# positive and negative numbers are True
37# True is True
38# True is not false
39# True is a boolean
40# the empty dictionary is False
41# the empty set is False
42# the empty list is False
43# the empty tuple is False
44# the empty string is False
45# 0 is False
46# None is False
47# False is False
48# False is not true
49# False is a boolean

  • I move the assertion to the test_what_is_false method

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(0.0)
12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse(set())
16        self.assertFalse(dict())
17
18    def test_what_is_true(self):

REFACTOR: make it better

  • I add another assertion to test if a dictionary with things is also False

    14        self.assertFalse(list())
15        self.assertFalse(set())
16        self.assertFalse(dict())
17        self.assertFalse({'key': 'value'})
18
19    def test_what_is_true(self):

    the terminal shows AssertionError

    AssertionError: {'key': 'value'} is not false

    a dictionary with things is NOT False

  • I change assertFalse to assertTrue

    17        self.assertTrue({'key': 'value'})

    the test passes

  • I add the last comment

    32# NOTES
33# a dictionary with things is True
34# a set with things is True
35# a list with things is True
36# a tuple with things is True
37# a string with things is True
38# positive and negative numbers are True
39# True is True
40# True is not false
41# True is a boolean
42# the empty dictionary is False
43# the empty set is False
44# the empty list is False
45# the empty tuple is False
46# the empty string is False
47# 0 is False
48# None is False
49# False is False
50# False is not true
51# False is a boolean
52
53
54# Exceptions seen
55# AssertionError

  • I move the assertion to the test_what_is_true method

     6    def test_what_is_false(self):
 7        self.assertIsInstance(False, bool)
 8        self.assertFalse(False)
 9        self.assertFalse(None)
10        self.assertFalse(0)
11        self.assertFalse(0.0)
12        self.assertFalse(str())
13        self.assertFalse(tuple())
14        self.assertFalse(list())
15        self.assertFalse(set())
16        self.assertFalse(dict())
17
18    def test_what_is_true(self):
19        self.assertIsInstance(True, bool)
20        self.assertTrue(True)
21        self.assertTrue(-1)
22        self.assertTrue(1)
23        self.assertTrue(-0.1)
24        self.assertTrue(0.1)
25        self.assertTrue("text")
26        self.assertTrue((1, 2, 3, 'n'))
27        self.assertTrue([1, 2, 3, 'n'])
28        self.assertTrue({1, 2, 3, 'n'})
29        self.assertTrue({'key': 'value'})
30
31
32# NOTES

in Python, the empty dictionary is False, and a dictionary with things is True

close the project

  • I close test_booleans.py in the editor

  • I click in the terminal and use q on the keyboard to leave the tests and the terminal goes back to the command line

  • I change directory to the parent of booleans

    cd ..

    the terminal shows

    .../pumping_python

    I am back in the pumping_python directory

review

From the tests I know that in Python

these things come in handy when I want programs to make decisions, because they can choose what to do based on if the data is False (0, empty or None ) or is True (positive and negative numbers or has something in it).

How many questions can you answer after going through this chapter?

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 the truth table? It will help you understand writing programs that make decisions based on conditions

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