test AssertionError with None

I want to use the assertIsNotNone and assertIsNone methods to test None in test_assertion_error_w_none.

preview

test_assertion_error_w_none looks like this by the end of the chapter

assertion_error/tests/test_assertion_error.py
54    def test_assertion_error_w_none(self):
55        assert None is None
56        self.assertIs(None, None)
57        self.assertIsNone(None)
58
59        assert_is_not_none(False)
60        self.assertIsNot(False, None)
61        self.assertIsNotNone(False)
62
63        assert_is_not_none(True)
64        self.assertIsNot(True, None)
65        self.assertIsNotNone(True)
66
67        assert_is_not_none(self.an_integer)
68        self.assertIsNot(self.an_integer, None)
69        self.assertIsNotNone(self.an_integer)
70
71        assert_is_not_none(self.a_float)
72        self.assertIsNot(self.a_float, None)
73        self.assertIsNotNone(self.a_float)
74
75        assert_is_not_none(self.a_string)
76        self.assertIsNot(self.a_string, None)
77        self.assertIsNotNone(self.a_string)
78
79        assert_is_not_none(self.a_tuple)
80        self.assertIsNot(self.a_tuple, None)
81        self.assertIsNotNone(self.a_tuple)
82
83        assert_is_not_none(self.a_list)
84        self.assertIsNot(self.a_list, None)
85        self.assertIsNotNone(self.a_list)
86
87        assert_is_not_none(self.a_set)
88        self.assertIsNot(self.a_set, None)
89        self.assertIsNotNone(self.a_set)
90
91        assert_is_not_none(self.a_dictionary)
92        self.assertIsNot(self.a_dictionary, None)
93        self.assertIsNotNone(self.a_dictionary)

open the project

use assertIsNotNone and assertIsNone

  • I add a call to assertIsNotNone in test_assertion_error_w_none

    54    def test_assertion_error_w_none(self):
55        assert None is None
56        self.assertIs(None, None)
57        self.assertIsNotNone(None)
58
59        assert_is_not_none(False)

    the terminal is my friend, and shows AssertionError

    AssertionError: unexpectedly None

    because None is None

  • I change assertIsNotNone to a call to the assertIsNone method

    54    def test_assertion_error_w_none(self):
55        assert None is None
56        self.assertIs(None, None)
57        # self.assertIsNotNone(None)
58        self.assertIsNone(None)
59
60        assert_is_not_none(False)

    the test passes

  • I add assertIsNone for False

    60        assert_is_not_none(False)
61        self.assertIsNot(False, None)
62        self.assertIsNone(False)
63
64        assert_is_not_none(True)

    the terminal is my friend, and shows AssertionError

    AssertionError: False is not None

  • I change the call from assertIsNone to assertIsNotNone

    60        assert_is_not_none(False)
61        self.assertIsNot(False, None)
62        # self.assertIsNone(False)
63        self.assertIsNotNone(False)
64
65        assert_is_not_none(True)

    the test passes because False is not None.

  • I add assertIsNone for True

    65        assert_is_not_none(True)
66        self.assertIsNot(True, None)
67        self.assertIsNone(True)
68
69        assert_is_not_none(self.an_integer)

    the terminal is my friend, and shows AssertionError

    AssertionError: True is not None

  • I change the call from assertIsNone to assertIsNotNone

    65        assert_is_not_none(True)
66        self.assertIsNot(True, None)
67        # self.assertIsNone(True)
68        self.assertIsNotNone(True)
69
70        assert_is_not_none(self.an_integer)

    the test passes because True is not None.

  • I add assertIsNone for an integer (a whole number without decimals)

    70        assert_is_not_none(self.an_integer)
71        self.assertIsNot(self.an_integer, None)
72        self.assertIsNone(self.an_integer)
73
74        assert_is_not_none(self.a_float)

    the terminal is my friend, and shows AssertionError

    AssertionError: 0 is not None

  • I change the call from assertIsNone to assertIsNotNone

    70        assert_is_not_none(self.an_integer)
71        self.assertIsNot(self.an_integer, None)
72        # self.assertIsNone(self.an_integer)
73        self.assertIsNotNone(self.an_integer)
74
75        assert_is_not_none(self.a_float)

    the test passes because an integer is not None.

  • I add assertIsNone for a float (binary floating point decimal number)

    75        assert_is_not_none(self.a_float)
76        self.assertIsNot(self.a_float, None)
77        self.assertIsNone(self.a_float)
78
79        assert_is_not_none(self.a_string)

    the terminal is my friend, and shows AssertionError

    AssertionError: 0.0 is not None

  • I change the call from assertIsNone to assertIsNotNone

    75        assert_is_not_none(self.a_float)
76        self.assertIsNot(self.a_float, None)
77        # self.assertIsNone(self.a_float)
78        self.assertIsNotNone(self.a_float)
79
80        assert_is_not_none(self.a_string)

    the test passes because a float is not None.

  • I add assertIsNone for a string (anything in quotes)

    80        assert_is_not_none(self.a_string)
81        self.assertIsNot(self.a_string, None)
82        self.assertIsNone(self.a_string)
83
84        assert_is_not_none(self.a_tuple)

    the terminal is my friend, and shows AssertionError

    AssertionError: '' is not None

  • I change the call from assertIsNone to assertIsNotNone

    80        assert_is_not_none(self.a_string)
81        self.assertIsNot(self.a_string, None)
82        # self.assertIsNone(self.a_string)
83        self.assertIsNotNone(self.a_string)
84
85        assert_is_not_none(self.a_tuple)

    the test passes because a string (anything in quotes) is not None.

  • I add assertIsNone for a tuple (anything in parentheses ( ) separated by a comma)

    85        assert_is_not_none(self.a_tuple)
86        self.assertIsNot(self.a_tuple, None)
87        self.assertIsNone(self.a_tuple)
88
89        assert_is_not_none(self.a_list)

    the terminal is my friend, and shows AssertionError

    AssertionError: () is not None

  • I change the call from assertIsNone to assertIsNotNone

    85        assert_is_not_none(self.a_tuple)
86        self.assertIsNot(self.a_tuple, None)
87        # self.assertIsNone(self.a_tuple)
88        self.assertIsNotNone(self.a_tuple)
89
90        assert_is_not_none(self.a_list)

    the test passes because a tuple is not None.

  • I add assertIsNone for a list (anything in square brackets [ ])

    90        assert_is_not_none(self.a_list)
91        self.assertIsNot(self.a_list, None)
92        self.assertIsNone(self.a_list)
93
94        assert_is_not_none(self.a_set)

    the terminal is my friend, and shows AssertionError

    AssertionError: [] is not None

  • I change the call from assertIsNone to assertIsNotNone

    90        assert_is_not_none(self.a_list)
91        self.assertIsNot(self.a_list, None)
92        # self.assertIsNone(self.a_list)
93        self.assertIsNotNone(self.a_list)
94
95        assert_is_not_none(self.a_set)

    the test passes because a list is not None.

  • I add assertIsNone for a set (anything in curly braces { }, not key-value pairs)

    95        assert_is_not_none(self.a_set)
96        self.assertIsNot(self.a_set, None)
97        self.assertIsNone(self.a_set)
98
99        assert_is_not_none(self.a_dictionary)

    the terminal is my friend, and shows AssertionError

    AssertionError: set() is not None

  • I change the call from assertIsNone to assertIsNotNone

     95        assert_is_not_none(self.a_set)
 96        self.assertIsNot(self.a_set, None)
 97        # self.assertIsNone(self.a_set)
 98        self.assertIsNotNone(self.a_set)
 99
100        assert_is_not_none(self.a_dictionary)

    the test passes because a set is not None.

  • I add assertIsNone for a dictionary (key-value pairs in curly braces ‘{ }’ separated by commas)

    100        assert_is_not_none(self.a_dictionary)
101        self.assertIsNot(self.a_dictionary, None)
102        self.assertIsNone(self.a_dictionary)
103
104    def test_assertion_error_w_false(self):

    the terminal is my friend, and shows AssertionError

    AssertionError: {} is not None

  • I change the call from assertIsNone to assertIsNotNone

    100        assert_is_not_none(self.a_dictionary)
101        self.assertIsNot(self.a_dictionary, None)
102        # self.assertIsNone(self.a_dictionary)
103        self.assertIsNotNone(self.a_dictionary)
104
105    def test_assertion_error_w_false(self):

    the test passes because a dictionary is not None.

  • I remove the commented lines from test_assertion_error_w_none

    54    def test_assertion_error_w_none(self):
55        assert None is None
56        self.assertIs(None, None)
57        self.assertIsNone(None)
58
59        assert_is_not_none(False)
60        self.assertIsNot(False, None)
61        self.assertIsNotNone(False)
62
63        assert_is_not_none(True)
64        self.assertIsNot(True, None)
65        self.assertIsNotNone(True)

    67        assert_is_not_none(self.an_integer)
68        self.assertIsNot(self.an_integer, None)
69        self.assertIsNotNone(self.an_integer)
70
71        assert_is_not_none(self.a_float)
72        self.assertIsNot(self.a_float, None)
73        self.assertIsNotNone(self.a_float)
74
75        assert_is_not_none(self.a_string)
76        self.assertIsNot(self.a_string, None)
77        self.assertIsNotNone(self.a_string)

    79        assert_is_not_none(self.a_tuple)
80        self.assertIsNot(self.a_tuple, None)
81        self.assertIsNotNone(self.a_tuple)
82
83        assert_is_not_none(self.a_list)
84        self.assertIsNot(self.a_list, None)
85        self.assertIsNotNone(self.a_list)
86
87        assert_is_not_none(self.a_set)
88        self.assertIsNot(self.a_set, None)
89        self.assertIsNotNone(self.a_set)
90
91        assert_is_not_none(self.a_dictionary)
92        self.assertIsNot(self.a_dictionary, None)
93        self.assertIsNotNone(self.a_dictionary)
94
95    def test_assertion_error_w_false(self):

  • I open a new terminal then change directories to assertion_error

    cd assertion_error

  • I add a git commit message in the new terminal

    git commit -am \
'use assertIsNotNone and assertIsNone'

I can use assertIsNotNone and assertIsNone for assertIsNot(x, None) and assertIs(x, None).

close the project

  • I close test_assertion_error.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 assertion_error

    cd ..

    the terminal is my friend, and shows

    .../pumping_python

    I am back in the pumping_python directory.

review

I can use assertIsNone methods and assertIsNotNone for assertions that test if something is None or not - assertIs(x, None) and assertIsNot(x, None).

code from the chapter

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

what is next?

Would you like to use the assertIsNotNone and assertIsNone methods with the functions project?

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