how to make a calculator 10: part 3

I want the numbers to stay when I press a button so that I can make numbers that have more than one digit.

preview

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

  1import random
  2import streamlit.testing.v1
  3import tests.test_calculator
  4import unittest
  5
  6
  7class TestStreamlitCalculator(unittest.TestCase):
  8
  9    def press_button(self, key):
 10        self.tester.button(key).click().run()
 11
 12    def setUp(self):
 13        self.tester = streamlit.testing.v1.AppTest.from_file(
 14            'src/streamlit_calculator.py'
 15        )
 16        self.tester.run()
 17
 18    def test_streamlit_calculator_title(self):
 19        self.assertEqual(self.tester.title[0].value, 'Calculator')
 20
 21    def test_streamlit_calculator_display(self):
 22        display = (
 23            self.tester.main.children[1].proto
 24                .flex_container
 25        )
 26        self.assertEqual(display.gap_config.gap_size, 1)
 27        self.assertEqual(display.direction, 1)
 28        self.assertEqual(display.justify, 1)
 29        self.assertEqual(display.align, 1)
 30        self.assertTrue(display.border)
 31
 32    def test_streamlit_calculator_columns_and_buttons(self):
 33        self.assertEqual(len(self.tester.columns), 4)
 34
 35        for column, keys in (
 36            (0, ('<-', '7', '4', '1', '+/-')),
 37            (1, ('C', '8', '5', '2', '0')),
 38            (2, ('AC', '9', '6', '3', '.')),
 39            (3, ('/', 'X', r'\-', r'\+', '=')),
 40        ):
 41            for key in keys:
 42                with self.subTest(key=key):
 43                    self.assertEqual(
 44                        (
 45                            self.tester.columns[column]
 46                                .button(key)
 47                                .label
 48                        ),
 49                        key
 50                    )
 51
 52    def test_streamlit_calculator_operations_buttons(self):
 53        for key in ('/', 'X', r'\-', r'\+', '=', 'C', 'AC'):
 54            with self.subTest(key=key):
 55                self.assertEqual(
 56                    self.tester.button(key).proto.type,
 57                    'primary'
 58                )
 59
 60    def test_streamlit_session_state(self):
 61        numbers = '0123456789'
 62        self.assertEqual(self.tester.session_state['number'], '0')
 63
 64        expectation = random.choice(numbers)
 65        while expectation == '0':
 66            expectation = random.choice(numbers)
 67        else:
 68            self.press_button(expectation)
 69
 70        self.assertEqual(
 71            self.tester.session_state['number'], expectation
 72        )
 73
 74        for _ in range(0, len(numbers)):
 75            a_random_number = random.choice(numbers)
 76            self.press_button(a_random_number)
 77            expectation += a_random_number
 78
 79        self.assertEqual(
 80            self.tester.session_state['number'],
 81            expectation
 82        )
 83
 84    def test_streamlit_calculator_w_decimals(self):
 85        for key in ('0.23.5.6.7.89'):
 86            self.press_button(key)
 87
 88        self.assertEqual(
 89            self.tester.session_state['number'],
 90            '0.2356789'
 91        )
 92
 93    def test_streamlit_calculator_backspace(self):
 94        a_random_number = tests.test_calculator.a_random_number()
 95        while a_random_number < 0:
 96            a_random_number = tests.test_calculator.a_random_number()
 97        a_random_number = str(a_random_number)
 98
 99        for key in a_random_number:
100            self.press_button(key)
101        self.press_button('<-')
102
103        self.assertEqual(
104            self.tester.session_state['number'],
105            a_random_number[:-1]
106        )
107
108        self.press_button('<-')
109        self.assertEqual(
110            self.tester.session_state['number'],
111            a_random_number[:-2]
112        )
113
114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '963.0258741'
116        for key in a_number:
117            self.press_button(key)
118        self.assertEqual(
119            self.tester.session_state['number'], a_number
120        )
121
122        self.press_button('+/-')
123        self.assertEqual(
124            self.tester.session_state['number'], f'-{a_number}'
125        )
126
127        self.press_button('+/-')
128        self.assertEqual(
129            self.tester.session_state['number'], a_number
130        )
131
132
133# Exceptions seen
134# NameError
135# AttributeError
136# AssertionError
137# SyntaxError
138# KeyError
139# streamlit.errors.StreamlitDuplicateElementKey

open the project

  • I change directory to the calculator folder

    cd calculator

  • I use pytest-watcher to run the tests

    uv run pytest-watcher . --now

    the terminal is my friend, and shows

    rootdir: .../pumping_python/calculator
configfile: pyproject.toml
collected 12 items

tests/test_calculator.py .....                                [ 41%]
tests/test_calculator_website.py ...                          [ 66%]
tests/test_streamlit_calculator.py ....                       [100%]

======================== 12 passed in X.YZs =========================

  • I open another terminal then use uv in the calculator folder

    uv run streamlit run src/streamlit_calculator.py

    the terminal is my friend, and shows

    Collecting usage statistics.
To deactivate, set browser.gatherUsageStats to false.


  You can now view your Streamlit app in your browser.

  Local URL: http://localhost:8501
  Network URL: http://ABC.DEF.GHI.JKL:8501
  External URL: http://MNO.PQR.STU.VWX:8501

    I use ctrl/option on the keyboard and click on http://localhost:8501 with the mouse to open the browser and it shows

    Calculator Streamlit Primary Buttons

test_streamlit_session_state

streamlit has a session state object that I can use to keep values in between button presses. They work the same as class attributes and they are dictionaries - I can add key-value pairs to them

RED: make it fail

  • I hold ctrl/command on the keyboard and click on tests/test_streamlit_calculator.py with the mouse to open it in the editor

  • I add a test for the session state object, I want it to hold the number when I click the buttons, in test_streamlit_calculator.py

    47    def test_streamlit_calculator_operations_buttons(self):
48        for key in ('/', 'X', r'\-', r'\+', '=', 'C', 'AC'):
49            with self.subTest(key=key):
50                self.assertEqual(
51                    self.tester.button(key).proto.type,
52                    'primary'
53                )
54
55    def test_streamlit_session_state(self):
56        self.assertIsNone(self.tester.session_state['number'])
57
58
59# Exceptions seen

    the terminal is my friend, and shows KeyError

    KeyError: 'st.session_state has no key "number".
Did you forget to initialize it?
More info: https://docs.streamlit.io/develop/concepts/architecture/session-state#initialization'

GREEN: make it pass

  • I use the setdefault method to add a key that will hold the numbers to show in the Calculator, in streamlit_calculator.py

    90def main():
91    streamlit.title('Calculator')
92    streamlit.session_state.setdefault('number', '0')
93    display = streamlit.container(border=True)
94
95    column_1, column_2, column_3, operations = streamlit.columns(4)
96    add_buttons_to_column_1(column_1, display)
97    add_buttons_to_column_2(column_2, display)
98    add_buttons_to_column_3(column_3, display)
99    add_buttons_to_column_4(operations)

    the terminal is my friend, and shows AssertionError

    AssertionError: 0 is not None

  • I add 0 as the expectation in test_streamlit_calculator.py

    55    def test_streamlit_session_state(self):
56        self.assertIsNone(self.tester.session_state['number'], '0')

    the terminal is my friend, and shows AssertionError

    AssertionError: '0' is not None : 0

  • I change the assertIsNone to assertEqual

    56        self.assertEqual(self.tester.session_state['number'], '0')

    the test passes

REFACTOR: make it better

  • I add the session state object to the show function so that when a button is clicked, it will be added to the session state object then shown in the disply

     4def show(display, number):
 5    # display.write(number)
 6    streamlit.session_state['number'] += number
 7    display.write(streamlit.session_state['number'])
 8
 9
10def add_buttons_to_column_1(column_1, display):

    the test passes

  • I remove the commented line

    4def show(display, number):
5    streamlit.session_state['number'] += number
6    display.write(streamlit.session_state['number'])

  • I add an assertion to test what happens to the session state object when I press a button for a number

    55    def test_streamlit_session_state(self):
56        self.assertEqual(self.tester.session_state['number'], '0')
57        self.tester.button('1').click().run()
58        self.assertEqual(self.tester.session_state['number'], '0')

    • .click() presses the button

    • .run() runs the program - streamlit_calculator.py, which is what happens when a person uses the application in the browser

    the terminal is my friend, and shows AssertionError

    AssertionError: '01' != '0'

    this is a problem

  • I change the expectation to match

    58        self.assertEqual(self.tester.session_state['number'], '01')

    the test passes

  • I add more button presses and another assertion

    55    def test_streamlit_session_state(self):
56        self.assertEqual(self.tester.session_state['number'], '0')
57        self.tester.button('1').click().run()
58        self.assertEqual(self.tester.session_state['number'], '01')
59        self.tester.button('2').click().run()
60        self.tester.button('3').click().run()
61        self.tester.button('4').click().run()
62        self.assertEqual(self.tester.session_state['number'], '01')

    the terminal is my friend, and shows AssertionError

    AssertionError: '01234' != '01'

  • I change the expectation to match

    62        self.assertEqual(
63            self.tester.session_state['number'], '01234'
64        )

    the test passes

  • I refresh the browser and click on all the numbers

    Many Numbers

    the calculator keeps numbers when I press the buttons and the number starts with 0 like the test

  • I want the calculator to remove 0 when it is the first number after I click on other numbers. I change the assertions

    55    def test_streamlit_session_state(self):
56        self.assertEqual(self.tester.session_state['number'], '0')
57        self.tester.button('1').click().run()
58        self.assertEqual(self.tester.session_state['number'], '1')
59        self.tester.button('2').click().run()
60        self.tester.button('3').click().run()
61        self.tester.button('4').click().run()
62        self.assertEqual(
63            self.tester.session_state['number'], '1234'
64        )

    the terminal is my friend, and shows AssertionError

    AssertionError: '01' != '1'

  • I add a condition to the show function in streamlit_calculator.py

    4def show(display, number):
5    if streamlit.session_state['number'] == '0':
6        streamlit.session_state['number'] = number
7    else:
8        streamlit.session_state['number'] += number
9    display.write(streamlit.session_state['number'])

    the test passes

  • I refresh the browser and try all the numbers

    Many Numbers Without 0 first

    the number no longer starts with 0

  • I import the random module to use random numbers for the test, in test_streamlit_calculator.py

    1import random
2import streamlit.testing.v1
3import unittest
4
5
6class TestStreamlitCalculator(unittest.TestCase):

  • I use it in test_streamlit_session_state

    56    def test_streamlit_session_state(self):
57        numbers = '0123456789'
58        self.assertEqual(self.tester.session_state['number'], '0')
59        # self.tester.button('1').click().run()
60        x = random.choice(numbers)
61        self.tester.button(x).click().run()
62        self.assertEqual(self.tester.session_state['number'], '1')

    • numbers = '0123456789' makes a string with ten numbers

    • x = random.choice(numbers) picks a random number from the ten numbers and points x to it

    the terminal is my friend, and shows. AssertionError

    AssertionError: 'X' != '1'

    where X is a random number

  • I change the expectation

    56    def test_streamlit_session_state(self):
57        numbers = '0123456789'
58        self.assertEqual(self.tester.session_state['number'], '0')
59        # self.tester.button('1').click().run()
60        x = random.choice(numbers)
61        self.tester.button(x).click().run()
62        self.assertEqual(self.tester.session_state['number'], x)
63        self.tester.button('2').click().run()
64        self.tester.button('3').click().run()
65        self.tester.button('4').click().run()
66        self.assertEqual(
67            self.tester.session_state['number'], '1234'
68        )

    when x is not 1, the terminal is my friend, and shows AssertionError

    AssertionError: 'X234' != '1234'

  • I use random numbers for the other button presses

    62        self.assertEqual(self.tester.session_state['number'], x)
63        # self.tester.button('2').click().run()
64        # self.tester.button('3').click().run()
65        # self.tester.button('4').click().run()
66        y = random.choice(numbers)
67        self.tester.button(y).click().run()
68        z = random.choice(numbers)
69        self.tester.button(z).click().run()
70        a = random.choice(numbers)
71        self.tester.button(a).click().run()
72        self.assertEqual(
73            self.tester.session_state['number'], '1234'
74        )

    the terminal is my friend, and shows AssertionError

    AssertionError: 'XYZA' != '1234'

  • I use the random numbers in the expectation of the assertion

    72        self.assertEqual(
73            self.tester.session_state['number'], f'{x}{y}{z}{a}'
74        )

    when x is 0, the terminal is my friend, and shows AssertionError

    AssertionError: 'YZA' != '0YZA'

what is a while loop?

  • I can use a while loop to make sure that x is never 0, since the session_state['number'] is always 0 at the beginning. I add a while loop to test_streamlit_session_state

    56    def test_streamlit_session_state(self):
57        numbers = '0123456789'
58        self.assertEqual(self.tester.session_state['number'], '0')
59        # self.tester.button('1').click().run()
60        x = random.choice(numbers)
61        while x == '0':
62            x = random.choice(numbers)
63        else:
64            self.tester.button(x).click().run()
65
66        self.assertEqual(self.tester.session_state['number'], x)
67        # self.tester.button('2').click().run()

    • x = random.choice(numbers) points x to a random number from the numbers variable

      • if x is not equal to '0' it goes to the next block which is else: self.tester.button(x).click().run()

      • if x is equal to '0' it goes to while x == '0': which makes a loop that will continue to run as long as x is equal to '0'

        • inside the loop x = random.choice(numbers) points x to a random number from the numbers string then checks again to see if x is equal to '0'

          • if x is equal to 0 the loop runs again

          • if x is not equal to 0 in the loop, it leaves the loop and goes to the next block which is else: self.tester.button(x).click().run()

    I use ctrl+s on the keyboard a few times and there are no more random failures

  • I add a for loop to test with a 10 digit number

    56    def test_streamlit_session_state(self):
57        numbers = '0123456789'
58        self.assertEqual(self.tester.session_state['number'], '0')
59        # self.tester.button('1').click().run()
60        x = random.choice(numbers)
61        while x == '0':
62            x = random.choice(numbers)
63        else:
64            self.tester.button(x).click().run()
65
66        self.assertEqual(self.tester.session_state['number'], x)
67        # self.tester.button('2').click().run()
68        # self.tester.button('3').click().run()
69        # self.tester.button('4').click().run()
70        y = random.choice(numbers)
71        self.tester.button(y).click().run()
72        z = random.choice(numbers)
73        self.tester.button(z).click().run()
74        a = random.choice(numbers)
75        self.tester.button(a).click().run()
76        self.assertEqual(
77            self.tester.session_state['number'], f'{x}{y}{z}{a}'
78        )
79
80        for _ in range(0, len(numbers)):
81            a_random_number = random.choice(numbers)
82            (
83                self.tester.button(a_random_number)
84                    .click().run()
85            )
86            x += a_random_number
87
88        self.assertEqual(
89            self.tester.session_state['number'],
90            x
91        )
92
93
94# Exceptions seen

    for _ in range(0, 10): uses _ because I do not need a name for each number from the range object in the for loop since I do not use it

    the terminal is my friend, and shows AssertionError

    AssertionError: 'XYZABCDEFGHIJK' != 'XBCDEFGHIJK'

    the first number and the last 10 numbers are the same in the two strings

  • I comment out the other lines

    56    def test_streamlit_session_state(self):
57        numbers = '0123456789'
58        self.assertEqual(self.tester.session_state['number'], '0')
59        # self.tester.button('1').click().run()
60        x = random.choice(numbers)
61        while x == '0':
62            x = random.choice(numbers)
63        else:
64            self.tester.button(x).click().run()
65
66        self.assertEqual(self.tester.session_state['number'], x)
67        # self.tester.button('2').click().run()
68        # self.tester.button('3').click().run()
69        # self.tester.button('4').click().run()
70        # y = random.choice(numbers)
71        # self.tester.button(y).click().run()
72        # z = random.choice(numbers)
73        # self.tester.button(z).click().run()
74        # a = random.choice(numbers)
75        # self.tester.button(a).click().run()
76        # self.assertEqual(
77        #     self.tester.session_state['number'], f'{x}{y}{z}{a}'
78        # )
79
80        for _ in range(0, len(numbers)):
81            a_random_number = random.choice(numbers)
82            (
83                self.tester.button(a_random_number)
84                    .click().run()
85            )
86            x += a_random_number
87
88        self.assertEqual(
89            self.tester.session_state['number'],
90            x
91        )

    I use ctrl+s on the keyboard to run the tests a few times and the test is still green

  • I remove the commented lines

    56    def test_streamlit_session_state(self):
57        numbers = '0123456789'
58        self.assertEqual(self.tester.session_state['number'], '0')
59
60        x = random.choice(numbers)
61        while x == '0':
62            x = random.choice(numbers)
63        else:
64            self.tester.button(x).click().run()
65
66        self.assertEqual(self.tester.session_state['number'], x)
67
68        for _ in range(0, len(numbers)):
69            a_random_number = random.choice(numbers)
70            (
71                self.tester.button(a_random_number)
72                    .click().run()
73            )
74            x += a_random_number
75
76        self.assertEqual(
77            self.tester.session_state['number'],
78            x
79        )

  • I use the Rename Symbol feature of the Integrated Development Environment (IDE) to change x to expectation because I like the name better

    55    def test_streamlit_session_state(self):
56        numbers = '0123456789'
57        self.assertEqual(self.tester.session_state['number'], '0')
58
59        expectation = random.choice(numbers)
60        while expectation == '0':
61            expectation = random.choice(numbers)
62        else:
63            self.tester.button(expectation).click().run()
64
65        self.assertEqual(
66            self.tester.session_state['number'], expectation
67        )
68
69        for _ in range(0, len(numbers)):
70            a_random_number = random.choice(numbers)
71            (
72                self.tester.button(a_random_number)
73                    .click().run()
74            )
75            expectation += a_random_number
76
77        self.assertEqual(
78            self.tester.session_state['number'],
79            expectation
80        )
81
82
83# Exceptions seen

test_streamlit_calculator_w_decimals

RED: make it fail

  • I add a test for decimal numbers

     78        self.assertEqual(
 79            self.tester.session_state['number'],
 80            expectation
 81        )
 82
 83    def test_streamlit_calculator_w_decimals(self):
 84        self.tester.button('0').click().run()
 85        self.tester.button('.').click().run()
 86        self.tester.button('2').click().run()
 87        self.tester.button('3').click().run()
 88        self.tester.button('.').click().run()
 89        self.tester.button('5').click().run()
 90        self.tester.button('.').click().run()
 91        self.tester.button('6').click().run()
 92        self.tester.button('.').click().run()
 93        self.tester.button('7').click().run()
 94        self.tester.button('.').click().run()
 95        self.tester.button('8').click().run()
 96        self.tester.button('9').click().run()
 97        self.assertEqual(
 98            self.tester.session_state['number'],
 99            '0.2356789'
100        )
101
102
103# Exceptions seen

    the terminal is my friend, and shows AssertionError

    AssertionError: '.23.5.6.7.89' != '0.2356789'

  • I refresh the browser and do the same thing

    Many Decimals

    the Calculator allows me add many decimal points

GREEN: make it pass

  • I add a function for decimals in streamlit_calculator.py

     1import streamlit
 2
 3
 4def handle_decimals(display, number):
 5    if streamlit.session_state['number'].count('.') >= 1:
 6        return None
 7    else:
 8        streamlit.session_state['number'] += number
 9    display.write(streamlit.session_state['number'])
10
11
12def show(display, number):

    the terminal still shows AssertionError

  • I change the on_click parameter for the . button in the add_buttons_to_column_3 function to use the new function

    78    column_3.button(
79        label='.', key='.', width='stretch',
80        # on_click=show, args=[display, '.'],
81        on_click=handle_decimals, args=[display, '.'],
82    )

    the test passes

  • I remove the commented line

    62def add_buttons_to_column_3(column_3, display):
63    column_3.button(
64        label='AC', key='AC', width='stretch', type='primary',
65    )
66    column_3.button(
67        label='9', key='9', width='stretch',
68        on_click=show, args=[display, '9'],
69    )
70    column_3.button(
71        label='6', key='6', width='stretch',
72        on_click=show, args=[display, '6'],
73    )
74    column_3.button(
75        label='3', key='3', width='stretch',
76        on_click=show, args=[display, '3'],
77    )
78    column_3.button(
79        label='.', key='.', width='stretch',
80        on_click=handle_decimals, args=[display, '.'],
81    )
82
83
84def add_buttons_to_column_4(column_4):

REFACTOR: make it better

  • I change the else clause to an if statement to make it simpler

     4def handle_decimals(display, number):
 5    if streamlit.session_state['number'].count('.') >= 1:
 6        return None
 7    # else:
 8    if streamlit.session_state['number'].count('.') == 0:
 9        streamlit.session_state['number'] += number
10    display.write(streamlit.session_state['number'])

    the test is still green

  • I remove the other if statement

     4def handle_decimals(display, number):
 5    if streamlit.session_state['number'].count('.') == 0:
 6        streamlit.session_state['number'] += number
 7    display.write(streamlit.session_state['number'])
 8
 9
10def show(display, number):

    still green

    • if streamlit.session_state['number'].count('.') == 0: checks if . is in session_state['number']

      • streamlit.session_state['number'].count('.') counts how many times . shows up in session_state['number']

      • if . is NOT in session_state['number'], then . gets added to session_state['number'] and the program runs the next line, which is display.write(streamlit.session_state['number'])

      • if . is in session_state['number'], then the program runs the next line, which is display.write(streamlit.session_state['number'])

  • I refresh the browser and try many decimals again

    One Decimal

    Yes! I can only do one decimal in a number

  • I add a for loop to test_streamlit_calculator_w_decimals in test_streamlit_calculator.py

     83    def test_streamlit_calculator_w_decimals(self):
 84        for key in ('0.23.5.6.7.89'):
 85            (
 86                self.tester.button(key)
 87                    .click().run()
 88            )
 89
 90        self.tester.button('0').click().run()
 91        self.tester.button('.').click().run()
 92        self.tester.button('2').click().run()
 93        self.tester.button('3').click().run()
 94        self.tester.button('.').click().run()
 95        self.tester.button('5').click().run()
 96        self.tester.button('.').click().run()
 97        self.tester.button('6').click().run()
 98        self.tester.button('.').click().run()
 99        self.tester.button('7').click().run()
100        self.tester.button('.').click().run()
101        self.tester.button('8').click().run()
102        self.tester.button('9').click().run()
103        self.assertEqual(
104            self.tester.session_state['number'],
105            '0.2356789'
106        )

    the terminal is my friend, and shows AssertionError

    AssertionError: '0.235678902356789' != '0.2356789'

  • I remove the other button presses

    83    def test_streamlit_calculator_w_decimals(self):
84        for key in ('0.23.5.6.7.89'):
85            (
86                self.tester.button(key)
87                    .click().run()
88            )
89
90        self.assertEqual(
91            self.tester.session_state['number'],
92            '0.2356789'
93        )
94
95
96# Exceptions seen

    the test passes

  • I keep writing self.tester.button(key).click().run(), time to add a method for button presses

     6class TestStreamlitCalculator(unittest.TestCase):
 7
 8    def press_button(self, key):
 9        self.tester.button(key).click().run()
10
11    def setUp(self):

  • I use the new method in test_streamlit_session_state

    59    def test_streamlit_session_state(self):
60        numbers = '0123456789'
61        self.assertEqual(self.tester.session_state['number'], '0')
62
63        expectation = random.choice(numbers)
64        while expectation == '0':
65            expectation = random.choice(numbers)
66        else:
67            # self.tester.button(expectation).click().run()
68            self.press_button(expectation)
69
70        self.assertEqual(
71            self.tester.session_state['number'], expectation
72        )
73
74        for _ in range(0, len(numbers)):
75            a_random_number = random.choice(numbers)
76            # (
77            #     self.tester.button(a_random_number)
78            #         .click().run()
79            # )
80            self.press_button(a_random_number)
81            expectation += a_random_number
82
83        self.assertEqual(
84            self.tester.session_state['number'],
85            expectation
86        )

    the tests are still green

  • I remove the commented lines

    59    def test_streamlit_session_state(self):
60        numbers = '0123456789'
61        self.assertEqual(self.tester.session_state['number'], '0')
62
63        expectation = random.choice(numbers)
64        while expectation == '0':
65            expectation = random.choice(numbers)
66        else:
67            self.press_button(expectation)
68
69        self.assertEqual(
70            self.tester.session_state['number'], expectation
71        )
72
73        for _ in range(0, len(numbers)):
74            a_random_number = random.choice(numbers)
75            self.press_button(a_random_number)
76            expectation += a_random_number
77
78        self.assertEqual(
79            self.tester.session_state['number'],
80            expectation
81        )
82
83    def test_streamlit_calculator_w_decimals(self):

  • I use the press_button method in test_streamlit_calculator_w_decimals

    83    def test_streamlit_calculator_w_decimals(self):
84        for key in ('0.23.5.6.7.89'):
85            # (
86            #     self.tester.button(key)
87            #         .click().run()
88            # )
89            self.press_button(key)
90
91        self.assertEqual(
92            self.tester.session_state['number'],
93            '0.2356789'
94        )

    still green

  • I remove the commented lines

    83    def test_streamlit_calculator_w_decimals(self):
84        for key in ('0.23.5.6.7.89'):
85            self.press_button(key)
86
87        self.assertEqual(
88            self.tester.session_state['number'],
89            '0.2356789'
90        )
91
92
93# Exceptions seen

test_streamlit_calculator_backspace

I want to be able to remove the last digit of a number with the <- button

RED: make it fail

  • I add a new test

     87        self.assertEqual(
 88            self.tester.session_state['number'],
 89            '0.2356789'
 90        )
 91
 92    def test_streamlit_calculator_backspace(self):
 93        self.press_button('1')
 94        self.press_button('2')
 95        self.press_button('3')
 96        self.press_button('4')
 97        self.press_button('<-')
 98        self.assertEqual(
 99            self.tester.session_state['number'],
100            '123'
101        )
102
103
104# Exceptions seen

    the terminal is my friend, and shows AssertionError

    AssertionError: '1234' != '123'

  • I try the same thing in the browser and it clears the screen

GREEN: make it pass

  • I add a function to streamlit_calculator.py

     1import streamlit
 2
 3
 4def backspace(display):
 5    number = streamlit.session_state['number'][:-1]
 6    streamlit.session_state['number'] = number
 7    display.write(streamlit.session_state['number'])
 8
 9
10def handle_decimals(display, number):

    the terminal still shows AssertionError

  • I add the on_click parameter to the <- button in the add_buttons_to_column_1 function

    24def add_buttons_to_column_1(column_1, display):
25    column_1.button(
26        label='<-', key='<-', width='stretch',
27        on_click=backspace, args=[display],
28    )
29    column_1.button(
30        label='7', key='7', width='stretch',
31        on_click=show, args=[display, '7'],
32    )
33    column_1.button(
34        label='4', key='4', width='stretch',
35        on_click=show, args=[display, '4'],
36    )
37    column_1.button(
38        label='1', key='1', width='stretch',
39        on_click=show, args=[display, '1'],
40    )
41    column_1.button(
42        label='+/-', key='+/-', width='stretch',
43        on_click=show, args=[display, '+/-'],
44    )
45
46
47def add_buttons_to_column_2(column_2, display):

    the test passes

REFACTOR: make it better

  • I add an import statement for tests/test_calculator.py in test_streamlit_calculator.py

    1import random
2import streamlit.testing.v1
3import tests.test_calculator
4import unittest
5
6
7class TestStreamlitCalculator(unittest.TestCase):

  • I add a variable with a for loop for a random number in test_streamlit_calculator_backspace

     93    def test_streamlit_calculator_backspace(self):
 94        a_random_number = tests.test_calculator.a_random_number()
 95        a_random_number = str(a_random_number)
 96
 97        for key in a_random_number:
 98            self.press_button(key)
 99        self.press_button('<-')
100
101        self.assertEqual(
102            self.tester.session_state['number'],
103            a_random_number
104        )
105
106        self.press_button('1')
107        self.press_button('2')
108        self.press_button('3')
109        self.press_button('4')
110        self.press_button('<-')
111        self.assertEqual(
112            self.tester.session_state['number'],
113            '123'
114        )

    • a_random_number = tests.test_calculator.a_random_number() uses the a_random_number function from test_calculator.py that I made in how to use random numbers

    • a_random_number = str(a_random_number) changes the random number to a string since all the tests of the calculator have been done with strings so far

    I use ctrl+s on the keyboard to run the test a few times because I am using random numbers. If the number is positive, the terminal is my friend, and shows AssertionError

    AssertionError: 'LMN.OPQRSTUVWXYZ' != 'LMN.OPQRSTUVWXYZA'

    the last number was not removed

    If the random number is negative, the terminal is my friend, and shows KeyError

    KeyError: '-'

    I need a test for the ‘+/-’ button

  • I add a while loop to make sure a_random_number is never negative

    93    def test_streamlit_calculator_backspace(self):
94        a_random_number = tests.test_calculator.a_random_number()
95        while a_random_number < 0:
96            a_random_number = tests.test_calculator.a_random_number()
97        a_random_number = str(a_random_number)
98
99        for key in a_random_number:

    I use ctrl+s on the keyboard to run the tests a few times and the terminal is my friend, and shows AssertionError

    AssertionError: 'BCD.EFGHIJKLMNOP' != 'BCD.EFGHIJKLMNOPQ'

    I remove this while statement when I test the ‘+/-’ button

  • I change the expectation to remove the last digit from the random number

    103        self.assertEqual(
104            self.tester.session_state['number'],
105            a_random_number[:-1]
106        )

    the terminal shows AssertionError

    AssertionError: 'RS.TUVWXYZABCDEF123' != '123'

    because I have button presses after the test. I need a way to reset the numbers back to 0

  • I comment out the other button presses

     93    def test_streamlit_calculator_backspace(self):
 94        a_random_number = tests.test_calculator.a_random_number()
 95        while a_random_number < 0:
 96            a_random_number = tests.test_calculator.a_random_number()
 97        a_random_number = str(a_random_number)
 98
 99        for key in a_random_number:
100            self.press_button(key)
101        self.press_button('<-')
102
103        self.assertEqual(
104            self.tester.session_state['number'],
105            a_random_number[:-1]
106        )
107
108        # self.press_button('1')
109        # self.press_button('2')
110        # self.press_button('3')
111        # self.press_button('4')
112        self.press_button('<-')
113        self.assertEqual(
114            self.tester.session_state['number'],
115            '123'
116        )

    the terminal is my friend, and shows AssertionError

    AssertionError: 'GHI.JKLMNOPQRS' != '123'

  • I change the expectation

     93    def test_streamlit_calculator_backspace(self):
 94        a_random_number = tests.test_calculator.a_random_number()
 95        while a_random_number < 0:
 96            a_random_number = tests.test_calculator.a_random_number()
 97        a_random_number = str(a_random_number)
 98
 99        for key in a_random_number:
100            self.press_button(key)
101        self.press_button('<-')
102
103        self.assertEqual(
104            self.tester.session_state['number'],
105            a_random_number[:-1]
106        )
107
108        # self.press_button('1')
109        # self.press_button('2')
110        # self.press_button('3')
111        # self.press_button('4')
112        self.press_button('<-')
113        self.assertEqual(
114            self.tester.session_state['number'],
115            # '123'
116            a_random_number[:-2]
117        )

    the test passes

  • I remove the commented lines

     93    def test_streamlit_calculator_backspace(self):
 94        a_random_number = tests.test_calculator.a_random_number()
 95        while a_random_number < 0:
 96            a_random_number = tests.test_calculator.a_random_number()
 97        a_random_number = str(a_random_number)
 98
 99        for key in a_random_number:
100            self.press_button(key)
101        self.press_button('<-')
102
103        self.assertEqual(
104            self.tester.session_state['number'],
105            a_random_number[:-1]
106        )
107
108        self.press_button('<-')
109        self.assertEqual(
110            self.tester.session_state['number'],
111            a_random_number[:-2]
112        )
113
114
115# Exceptions seen

  • I go to the browser and click on a few numbers, then click on <- and it removes the last number. Fantastic!

test_streamlit_calculator_w_plus_minus

Nothing happens when I click +/- in the calculator. I want it to

  • change positive numbers to negative numbers

  • change negative numbers to positive numbers

RED: make it fail

I add a new test for the +/- button

108          self.press_button('<-')
109          self.assertEqual(
110              self.tester.session_state['number'],
111              a_random_number[:-2]
112          )
113
114      def test_streamlit_calculator_w_plus_minus(self):
115          self.press_button('9')
116          self.assertEqual(
117              self.tester.session_state['number'], '9'
118          )
119
120          self.press_button('+/-')
121          self.assertEqual(
122              self.tester.session_state['number'], '-9'
123          )
124
125
126  # Exceptions seen

the terminal is my friend, and shows AssertionError

AssertionError: '9' != '-9'

GREEN: make it pass

  • I add a function for the +/- button in streamlit_calculator.py

     1import streamlit
 2
 3
 4def plus_minus(display):
 5    if not streamlit.session_state['number'].startswith('-'):
 6        number = '-' + streamlit.session_state['number']
 7        streamlit.session_state['number'] = number
 8        display.write(streamlit.session_state['number'])
 9
10
11def backspace(display):

    the terminal still shows AssertionError

  • I add the on_click parameter for the +/- button in the add_buttons_to_column_1 function

    31def add_buttons_to_column_1(column_1, display):
32    column_1.button(
33        label='<-', key='<-', width='stretch',
34        on_click=backspace, args=[display],
35    )
36    column_1.button(
37        label='7', key='7', width='stretch',
38        on_click=show, args=[display, '7'],
39    )
40    column_1.button(
41        label='4', key='4', width='stretch',
42        on_click=show, args=[display, '4'],
43    )
44    column_1.button(
45        label='1', key='1', width='stretch',
46        on_click=show, args=[display, '1'],
47    )
48    column_1.button(
49        label='+/-', key='+/-', width='stretch',
50        on_click=plus_minus, args=[display],
51    )
52
53
54def add_buttons_to_column_2(column_2, display):

    the test passes. I can turn a positive number to a negative number with the +/- button. Can I turn a negative number to a positive number with the +/- button?

REFACTOR: make it better

  • I add a button press and assertion to make sure I can turn a negative number to a positive number with the +/- button, in test_streamlit_calculator.py

    114    def test_streamlit_calculator_w_plus_minus(self):
115        self.press_button('9')
116        self.assertEqual(
117            self.tester.session_state['number'], '9'
118        )
119
120        self.press_button('+/-')
121        self.assertEqual(
122            self.tester.session_state['number'], '-9'
123        )
124
125        self.press_button('+/-')
126        self.assertEqual(
127            self.tester.session_state['number'], '9'
128        )
129
130
131# Exceptions seen

    the terminal is my friend, and shows AssertionError

    AssertionError: '-9' != '9'

  • I add another if statement to the plus_minus function in streamlit_calculator.py

     4def plus_minus(display):
 5    if streamlit.session_state['number'].startswith('-'):
 6        number = streamlit.session_state['number'][1:]
 7    if not streamlit.session_state['number'].startswith('-'):
 8        number = '-' + streamlit.session_state['number']
 9    streamlit.session_state['number'] = number
10
11    display.write(streamlit.session_state['number'])

    the test passes

  • I use else for the second if statement

     4def plus_minus(display):
 5    if streamlit.session_state['number'].startswith('-'):
 6        number = streamlit.session_state['number'][1:]
 7    # if not streamlit.session_state['number'].startswith('-'):
 8    else:
 9        number = '-' + streamlit.session_state['number']
10    streamlit.session_state['number'] = number
11
12    display.write(streamlit.session_state['number'])

    the test is still green

  • I remove the commented line

     4def plus_minus(display):
 5    if streamlit.session_state['number'].startswith('-'):
 6        number = streamlit.session_state['number'][1:]
 7    else:
 8        number = '-' + streamlit.session_state['number']
 9    streamlit.session_state['number'] = number
10
11    display.write(streamlit.session_state['number'])
12
13
14def backspace(display):

  • I add a variable to remove repetition from test_streamlit_calculator_w_plus_minus in test_streamlit_calculator.py

    114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '9'
116        self.press_button('9')
117        self.assertEqual(

  • I use the variable in the assertions and button presses

    114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '9'
116        # self.press_button('9')
117        self.press_button(a_number)
118        self.assertEqual(
119            # self.tester.session_state['number'], '9'
120            self.tester.session_state['number'], a_number
121        )
122
123        self.press_button('+/-')
124        self.assertEqual(
125            # self.tester.session_state['number'], '-9'
126            self.tester.session_state['number'], f'-{a_number}'
127        )
128
129        self.press_button('+/-')
130        self.assertEqual(
131            # self.tester.session_state['number'], '9'
132            self.tester.session_state['number'], a_number
133        )

    the test is still green

  • I remove the commented lines

    114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '9'
116        self.press_button(a_number)
117        self.assertEqual(
118            self.tester.session_state['number'], a_number
119        )
120
121        self.press_button('+/-')
122        self.assertEqual(
123            self.tester.session_state['number'], f'-{a_number}'
124        )
125
126        self.press_button('+/-')
127        self.assertEqual(
128            self.tester.session_state['number'], a_number
129        )

  • I try a bigger number

    114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '96'
116        self.press_button(a_number)

    the terminal is my friend, and shows KeyError

    KeyError: '96'

    I need separate button presses for the two numbers

  • I add a for loop

    114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '96'
116        for key in a_number:
117            self.press_button(key)
118        self.assertEqual(
119            self.tester.session_state['number'], a_number
120        )
121
122        self.press_button('+/-')

    the test passes

  • I try a number with all the digits and decimals

    114    def test_streamlit_calculator_w_plus_minus(self):
115        a_number = '963.0258741'
116        for key in a_number:
117            self.press_button(key)
118        self.assertEqual(
119            self.tester.session_state['number'], a_number
120        )
121
122        self.press_button('+/-')
123        self.assertEqual(
124            self.tester.session_state['number'], f'-{a_number}'
125        )
126
127        self.press_button('+/-')
128        self.assertEqual(
129            self.tester.session_state['number'], a_number
130        )
131
132
133# Exceptions seen

    the test is still green

  • I refresh the browser and try to make a negative number

    Negative Number

    when I click on the +/- button it turns a positive number negative

  • I try the +/- button again

    Negative Number

    the - is removed from the number to make it a positive number. Progress!

REFACTOR: make it better

  • The last 4 functions in streamlit_calculator.py - plus_minus, backspace, handle_decimals and show look the same. 2 of the functions have number in the function signature, all 4 have display in the function signature

    def function_name(display):
def function_name(display, number):
    statements
    display.write(streamlit.session_state['number'])

  • I add number in the parentheses for the plus_minus function to make it have the same signature as the show and handle_decimals functions

     4def plus_minus(display, number):
 5    if streamlit.session_state['number'].startswith('-'):
 6        number = streamlit.session_state['number'][1:]
 7    else:
 8        number = '-' + streamlit.session_state['number']
 9    streamlit.session_state['number'] = number
10
11    display.write(streamlit.session_state['number'])
12
13
14def backspace(display):

    the terminal is my friend, and shows AssertionError

    '963.0258741' != '-963.0258741'

    and TypeError

    TypeError: plus_minus() missing 1 required positional argument: 'number'

  • I add a second argument to the args parameter for the +/- button in the add_buttons_to_column_1 function

    34def add_buttons_to_column_1(column_1, display):
35    column_1.button(
36        label='<-', key='<-', width='stretch',
37        on_click=backspace, args=[display],
38    )
39    column_1.button(
40        label='7', key='7', width='stretch',
41        on_click=show, args=[display, '7'],
42    )
43    column_1.button(
44        label='4', key='4', width='stretch',
45        on_click=show, args=[display, '4'],
46    )
47    column_1.button(
48        label='1', key='1', width='stretch',
49        on_click=show, args=[display, '1'],
50    )
51    column_1.button(
52        label='+/-', key='+/-', width='stretch',
53        on_click=plus_minus, args=[display, '+/-'],
54    )
55
56
57def add_buttons_to_column_2(column_2, display):

    the test is green again

  • I add number in the parentheses for the backspace function to make it have the same signature as the show, handle_decimals and plus_minus functions

    14def backspace(display, number):
15    number = streamlit.session_state['number'][:-1]
16    streamlit.session_state['number'] = number
17    display.write(streamlit.session_state['number'])
18
19
20def handle_decimals(display, number):

    the terminal is my friend, and shows AssertionError

    AssertionError: 'RST.UVWXYZABCDEFGH' != 'RST.UVWXYZABCDEFG'

    it also shows TypeError

    TypeError: backspace() missing 1 required positional argument: 'number'

  • I add a second argument to the args parameter for the <- button in the add_buttons_to_column_1 function

    34def add_buttons_to_column_1(column_1, display):
35    column_1.button(
36        label='<-', key='<-', width='stretch',
37        on_click=backspace, args=[display, '<-'],
38    )
39    column_1.button(
40        label='7', key='7', width='stretch',
41        on_click=show, args=[display, '7'],
42    )
43    column_1.button(
44        label='4', key='4', width='stretch',
45        on_click=show, args=[display, '4'],
46    )
47    column_1.button(
48        label='1', key='1', width='stretch',
49        on_click=show, args=[display, '1'],
50    )
51    column_1.button(
52        label='+/-', key='+/-', width='stretch',
53        on_click=plus_minus, args=[display, '+/-'],
54    )
55
56
57def add_buttons_to_column_2(column_2, display):

    the test is green again

  • I add a new function for showing the number key of the session state object

    1import streamlit
2
3
4def show_number(display):
5    display.write(streamlit.session_state['number'])
6
7
8def plus_minus(display, number):

  • I use the new function in the plus_minus function

     8def plus_minus(display, number):
 9    if streamlit.session_state['number'].startswith('-'):
10        number = streamlit.session_state['number'][1:]
11    else:
12        number = '-' + streamlit.session_state['number']
13    streamlit.session_state['number'] = number
14
15    # display.write(streamlit.session_state['number'])
16    show_number(display)

    the test is still green

  • I remove the commented line

     8def plus_minus(display, number):
 9    if streamlit.session_state['number'].startswith('-'):
10        number = streamlit.session_state['number'][1:]
11    else:
12        number = '-' + streamlit.session_state['number']
13    streamlit.session_state['number'] = number
14
15    show_number(display)
16
17
18def backspace(display, number):

  • I use the new function in the backspace function

    18def backspace(display, number):
19    number = streamlit.session_state['number'][:-1]
20    streamlit.session_state['number'] = number
21    # display.write(streamlit.session_state['number'])
22    show_number(display)

    the test is still green

  • I remove the commented line

    18def backspace(display, number):
19    number = streamlit.session_state['number'][:-1]
20    streamlit.session_state['number'] = number
21    show_number(display)
22
23
24def handle_decimals(display, number):

  • I use the new function in the handle_decimals function

    24def handle_decimals(display, number):
25    if streamlit.session_state['number'].count('.') == 0:
26        streamlit.session_state['number'] += number
27    # display.write(streamlit.session_state['number'])
28    show_number(display)

    the test is still green

  • I remove the commented line

    24def handle_decimals(display, number):
25    if streamlit.session_state['number'].count('.') == 0:
26        streamlit.session_state['number'] += number
27    show_number(display)
28
29
30def show(display, number):

  • I use the new function in the show function

    30def show(display, number):
31    if streamlit.session_state['number'] == '0':
32        streamlit.session_state['number'] = number
33    else:
34        streamlit.session_state['number'] += number
35    # display.write(streamlit.session_state['number'])
36    show_number(display)

    the test is still green

  • I remove the commented line

    30def show(display, number):
31    if streamlit.session_state['number'] == '0':
32        streamlit.session_state['number'] = number
33    else:
34        streamlit.session_state['number'] += number
35    show_number(display)
36
37
38def add_buttons_to_column_1(column_1, display):

  • I add a new function for adding the number to the session state object

    24def handle_decimals(display, number):
25    if streamlit.session_state['number'].count('.') == 0:
26        streamlit.session_state['number'] += number
27    show_number(display)
28
29
30def add_number_to_state(number):
31    if streamlit.session_state['number'] == '0':
32        streamlit.session_state['number'] = number
33    else:
34        streamlit.session_state['number'] += number
35
36
37def show(display, number):

  • I add a function to handle all the button clicks

    37def show(display, number):
38    if streamlit.session_state['number'] == '0':
39        streamlit.session_state['number'] = number
40    else:
41        streamlit.session_state['number'] += number
42    show_state(display)
43
44
45def on_click(function, display, value):
46    function(value)
47    show_state(display)
48
49
50def add_buttons():

  • I try the on_click function with the 7 button in the add_buttons_to_column_1 function

    50def add_buttons_to_column_1(column_1, display):
51    column_1.button(
52        label='<-', key='<-', width='stretch',
53        on_click=backspace, args=[display, '<-'],
54    )
55    column_1.button(
56        label='7', key='7', width='stretch', on_click=on_click,
57        # on_click=show, args=[display, '7'],
58        args=[add_number_to_state, display, '7'],
59    )
60    column_1.button(
61        label='4', key='4', width='stretch',
62        on_click=show, args=[display, '4'],
63    )
64    column_1.button(
65        label='1', key='1', width='stretch',
66        on_click=show, args=[display, '1'],
67    )
68    column_1.button(
69        label='+/-', key='+/-', width='stretch',
70        on_click=plus_minus, args=[display, '+/-'],
71    )

    the tests are still green! Yes!!

  • I use the on_click function with all the other number buttons in the add_buttons_to_column_1 function

    50def add_buttons_to_column_1(column_1, display):
51    column_1.button(
52        label='<-', key='<-', width='stretch',
53        on_click=backspace, args=[display, '<-'],
54    )
55    column_1.button(
56        label='7', key='7', width='stretch', on_click=on_click,
57        # on_click=show, args=[display, '7'],
58        args=[add_number_to_state, display, '7'],
59    )
60    column_1.button(
61        label='4', key='4', width='stretch', on_click=on_click,
62        # on_click=show, args=[display, '4'],
63        args=[add_number_to_state, display, '4'],
64    )
65    column_1.button(
66        label='1', key='1', width='stretch', on_click=on_click,
67        # on_click=show, args=[display, '1'],
68        args=[add_number_to_state, display, '1'],
69    )
70    column_1.button(
71        label='+/-', key='+/-', width='stretch',
72        on_click=plus_minus, args=[display, '+/-'],
73    )

    still green

  • I remove the commented lines

    50def add_buttons_to_column_1(column_1, display):
51    column_1.button(
52        label='<-', key='<-', width='stretch',
53        on_click=backspace, args=[display, '<-'],
54    )
55    column_1.button(
56        label='7', key='7', width='stretch', on_click=on_click,
57        args=[add_number_to_state, display, '7'],
58    )
59    column_1.button(
60        label='4', key='4', width='stretch', on_click=on_click,
61        args=[add_number_to_state, display, '4'],
62    )
63    column_1.button(
64        label='1', key='1', width='stretch', on_click=on_click,
65        args=[add_number_to_state, display, '1'],
66    )
67    column_1.button(
68        label='+/-', key='+/-', width='stretch',
69        on_click=plus_minus, args=[display, '+/-'],
70    )
71
72
73def add_buttons_to_column_2(column_2, display):

  • I use the on_click function with all the number buttons in the add_buttons_to_column_2 function

    73def add_buttons_to_column_2(column_2, display):
74    column_2.button(
75        label='C', key='C', width='stretch', type='primary',
76    )
77    column_2.button(
78        label='8', key='8', width='stretch', on_click=on_click,
79        # on_click=show, args=[display, '8'],
80        args=[add_number_to_state, display, '8'],
81    )
82    column_2.button(
83        label='5', key='5', width='stretch', on_click=on_click,
84        # on_click=show, args=[display, '5'],
85        args=[add_number_to_state, display, '5'],
86    )
87    column_2.button(
88        label='2', key='2', width='stretch', on_click=on_click,
89        # on_click=show, args=[display, '2'],
90        args=[add_number_to_state, display, '2'],
91    )
92    column_2.button(
93        label='0', key='0', width='stretch', on_click=on_click,
94        # on_click=show, args=[display, '0'],
95        args=[add_number_to_state, display, '0'],
96    )

    green

  • I remove the commented lines

    73def add_buttons_to_column_2(column_2, display):
74    column_2.button(
75        label='C', key='C', width='stretch', type='primary',
76    )
77    column_2.button(
78        label='8', key='8', width='stretch', on_click=on_click,
79        args=[add_number_to_state, display, '8'],
80    )
81    column_2.button(
82        label='5', key='5', width='stretch', on_click=on_click,
83        args=[add_number_to_state, display, '5'],
84    )
85    column_2.button(
86        label='2', key='2', width='stretch', on_click=on_click,
87        args=[add_number_to_state, display, '2'],
88    )
89    column_2.button(
90        label='0', key='0', width='stretch', on_click=on_click,
91        args=[add_number_to_state, display, '0'],
92    )
93
94
95def add_buttons_to_column_3(column_3, display):

  • I use the on_click function with all the number buttons in the add_buttons_to_column_3 function

     95def add_buttons_to_column_3(column_3, display):
 96    column_3.button(
 97        label='AC', key='AC', width='stretch', type='primary',
 98    )
 99    column_3.button(
100        label='9', key='9', width='stretch', on_click=on_click,
101        # on_click=show, args=[display, '9'],
102        args=[add_number_to_state, display, '9'],
103    )
104    column_3.button(
105        label='6', key='6', width='stretch', on_click=on_click,
106        # on_click=show, args=[display, '6'],
107        args=[add_number_to_state, display, '6'],
108    )
109    column_3.button(
110        label='3', key='3', width='stretch', on_click=on_click,
111        # on_click=show, args=[display, '3'],
112        args=[add_number_to_state, display, '3'],
113    )
114    column_3.button(
115        label='.', key='.', width='stretch',
116        on_click=handle_decimals, args=[display, '.'],
117    )

    still green

  • I remove the commented lines

     95def add_buttons_to_column_3(column_3, display):
 96    column_3.button(
 97        label='AC', key='AC', width='stretch', type='primary',
 98    )
 99    column_3.button(
100        label='9', key='9', width='stretch', on_click=on_click,
101        args=[add_number_to_state, display, '9'],
102    )
103    column_3.button(
104        label='6', key='6', width='stretch', on_click=on_click,
105        args=[add_number_to_state, display, '6'],
106    )
107    column_3.button(
108        label='3', key='3', width='stretch', on_click=on_click,
109        args=[add_number_to_state, display, '3'],
110    )
111    column_3.button(
112        label='.', key='.', width='stretch',
113        on_click=handle_decimals, args=[display, '.'],
114    )
115
116
117def add_buttons_to_column_4(column_4):

  • I remove the show function because it is no longer used

    30def add_number_to_state(number):
31    if streamlit.session_state['number'] == '0':
32        streamlit.session_state['number'] = number
33    else:
34        streamlit.session_state['number'] += number
35
36
37def on_click(function, display, value):

  • I add a new function to make decimal numbers

    24def handle_decimals(display, number):
25    if streamlit.session_state['number'].count('.') == 0:
26        streamlit.session_state['number'] += number
27    show_number(display)
28
29
30def add_decimal():
31    if streamlit.session_state['number'].count('.') == 0:
32        streamlit.session_state['number'] += '.'
33
34
35def add_number_to_state(number):

  • I use the new function with the . button in the add_buttons_to_column_3 function

     92def add_buttons_to_column_3(column_3, display):
 93    column_3.button(
 94        label='AC', key='AC', width='stretch', type='primary',
 95    )
 96    column_3.button(
 97        label='9', key='9', width='stretch', on_click=on_click,
 98        args=[add_number_to_state, display, '9'],
 99    )
100    column_3.button(
101        label='6', key='6', width='stretch', on_click=on_click,
102        args=[add_number_to_state, display, '6'],
103    )
104    column_3.button(
105        label='3', key='3', width='stretch', on_click=on_click,
106        args=[add_number_to_state, display, '3'],
107    )
108    column_3.button(
109        label='.', key='.', width='stretch', on_click=on_click,
110        # on_click=handle_decimals, args=[display, '.'],
111        args=[add_decimal, display]
112    )

    the terminal is my friend, and shows KeyError

    FAILED ... - KeyError: 'I'
FAILED ... - KeyError: '2'
FAILED ... - KeyError: '0'

    and TypeError

    TypeError: on_click() missing 1 required positional argument: 'value'

  • I make the value parameter a choice in the on_click function

    42def on_click(function, display, *value):
43    function(*value)
44    show_number(display)
45
46
47def add_buttons_to_column_1(column_1, display):

    the test passes

  • I remove the commented line from the add_buttons_to_column_3 function

     92def add_buttons_to_column_3(column_3, display):
 93    column_3.button(
 94        label='AC', key='AC', width='stretch', type='primary',
 95    )
 96    column_3.button(
 97        label='9', key='9', width='stretch', on_click=on_click,
 98        args=[add_number_to_state, display, '9'],
 99    )
100    column_3.button(
101        label='6', key='6', width='stretch', on_click=on_click,
102        args=[add_number_to_state, display, '6'],
103    )
104    column_3.button(
105        label='3', key='3', width='stretch', on_click=on_click,
106        args=[add_number_to_state, display, '3'],
107    )
108    column_3.button(
109        label='.', key='.', width='stretch', on_click=on_click,
110        args=[add_decimal, display]
111    )
112
113
114def add_buttons_to_column_4(column_4):

  • I remove the handle_decimals function because it is no longer used

    18def backspace(display, number):
19    number = streamlit.session_state['number'][:-1]
20    streamlit.session_state['number'] = number
21    show_number(display)
22
23
24def add_decimal():

  • I change the on_click and args parameters for the <- button in the add_buttons_to_column_1 function

    41def add_buttons_to_column_1(column_1, display):
42    column_1.button(
43        label='<-', key='<-', width='stretch', on_click=on_click,
44        # on_click=backspace, args=[display, '<-'],
45        args=[backspace, display],
46    )

    the terminal is my friend, and shows AssertionError

    AssertionError: 'MNO.PQRSTUVWXYZABCD' != 'MNO.PQRSTUVWXYZABC'

    and TypeError

    TypeError: backspace() missing 2 required positional arguments: 'display' and 'number'

  • I change the backspace function

    18# def backspace(display, number):
19def backspace():
20    number = streamlit.session_state['number'][:-1]
21    streamlit.session_state['number'] = number
22    # show_number(display)

    the test passes

  • I remove the commented lines from the backspace function

    18def backspace():
19    number = streamlit.session_state['number'][:-1]
20    streamlit.session_state['number'] = number
21
22
23def add_decimal():

  • I change the on_click and args parameters for the +/- button in the add_buttons_to_column_1 function

    40def add_buttons_to_column_1(column_1, display):
41    column_1.button(
42        label='<-', key='<-', width='stretch', on_click=on_click,
43        # on_click=backspace, args=[display, '<-'],
44        args=[backspace, display],
45    )
46    column_1.button(
47        label='7', key='7', width='stretch', on_click=on_click,
48        args=[add_number_to_state, display, '7'],
49    )
50    column_1.button(
51        label='4', key='4', width='stretch', on_click=on_click,
52        args=[add_number_to_state, display, '4'],
53    )
54    column_1.button(
55        label='1', key='1', width='stretch', on_click=on_click,
56        args=[add_number_to_state, display, '1'],
57    )
58    column_1.button(
59        label='+/-', key='+/-', width='stretch', on_click=on_click,
60        # on_click=plus_minus, args=[display, '+/-'],
61        args=[plus_minus, display],
62    )

    the terminal is my friend, and shows AssertionError

    AssertionError: '963.0258741' != '-963.0258741'

    and TypeError

    TypeError: plus_minus() missing 2 required positional arguments: 'display' and 'number'

  • I change the plus_minus function

     8# def plus_minus(display, number):
 9def plus_minus():
10    if streamlit.session_state['number'].startswith('-'):
11        number = streamlit.session_state['number'][1:]
12    else:
13        number = '-' + streamlit.session_state['number']
14    streamlit.session_state['number'] = number
15
16    # show_number(display)

    the test passes

  • I remove the commented lines from the plus_minus function

     8def plus_minus():
 9    if streamlit.session_state['number'].startswith('-'):
10        number = streamlit.session_state['number'][1:]
11    else:
12        number = '-' + streamlit.session_state['number']
13    streamlit.session_state['number'] = number
14
15
16def backspace():

  • I remove the commented lines from the add_buttons_to_column_1 function

    42def add_buttons_to_column_1(column_1, display):
43    column_1.button(
44        label='<-', key='<-', width='stretch', on_click=on_click,
45        args=[backspace, display],
46    )
47    column_1.button(
48        label='7', key='7', width='stretch', on_click=on_click,
49        args=[add_number_to_state, display, '7'],
50    )
51    column_1.button(
52        label='4', key='4', width='stretch', on_click=on_click,
53        args=[add_number_to_state, display, '4'],
54    )
55    column_1.button(
56        label='1', key='1', width='stretch', on_click=on_click,
57        args=[add_number_to_state, display, '1'],
58    )
59    column_1.button(
60        label='+/-', key='+/-', width='stretch', on_click=on_click,
61        args=[plus_minus, display],
62    )
63
64
65def add_buttons_to_column_2(column_2, display):

That was a lot! I am going to take a nap. I will work on the operations after that.

close the project

  • I close test_streamlit_calculator.py, streamlit_calculator.py in the editor

  • I click in the first terminal, then use q on the keyboard to leave the tests. The terminal goes back to the command line

  • I change directory to the parent of calculator

    cd ..

    the terminal is my friend, and shows

    .../pumping_python

    I am back in the pumping_python directory

  • I click in the second terminal, then use ctrl+c on the keyboard to close the web server. The terminal goes back to the command line

  • I change directory to the parent of calculator

    cd ..

    the terminal is my friend, and shows

    .../pumping_python

    I am back in the pumping_python directory

review

I made a website using Streamlit with a

I used while loops and added tests for

code from the chapter

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

what is next?

You now know how to:

Would you like to continue with the operation buttons of the calculator?

rate pumping python

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