test microwave with list comprehensions

I want to use for loops in the Microwave project. It has tests for a Microwave with these inputs:

is the Microwave door closed?
is the timer set?
is the Microwave too hot?
was the start button pressed?

the inputs gave me this truth table

door	timer	start button	too hot	output
closed	set	pressed	too hot	False
closed	set	pressed	NOT too hot	True
closed	set	NOT pressed	too hot	False
closed	set	NOT pressed	NOT too hot	False

door	timer	start button	too hot	output
closed	NOT set	pressed	too hot	False
closed	NOT set	pressed	NOT too hot	False
closed	NOT set	NOT pressed	too hot	False
closed	NOT set	NOT pressed	NOT too hot	False

door	timer	start button	too hot	output
open	set	pressed	too hot	False
open	set	pressed	NOT too hot	False
open	set	NOT pressed	too hot	False
open	set	NOT pressed	NOT too hot	False

door	timer	start button	too hot	output
open	NOT set	pressed	too hot	False
open	NOT set	pressed	NOT too hot	False
open	NOT set	NOT pressed	too hot	False
open	NOT set	NOT pressed	NOT too hot	False

The only time this Microwave heats up food is when the Microwave door is closed AND the timer is set AND the Microwave temperature is NOT too hot AND the start button is pressed.

preview

These is the test I have at the end of the chapter

microwave/tests/test_microwave.py

import src.microwave
import unittest


class TestMicrowave(unittest.TestCase):

    def test_microwave(self):
        booleans = (False, True)
        for closed_door in booleans:
            for timer_set in booleans:
                for pressed_start in booleans:
                    for too_hot in booleans:
                        with self.subTest(
                            closed_door=closed_door,
                            timer_set=timer_set,
                            pressed_start=pressed_start,
                            too_hot=too_hot,
                        ):
                            result = src.microwave.microwave(
                                closed_door=closed_door,
                                timer_set=timer_set,
                                pressed_start=pressed_start,
                                too_hot=too_hot,
                            )
                            try:
                                self.assertFalse(result)
                            except AssertionError:
                                self.assertTrue(result)


# Exceptions seen
# AssertionError
# NameError
# AttributeError
# TypeError
# SyntaxError

open the project

I open a terminal_
I change directory_ to the project
terminal
```
cd microwave
```
I open test_microwave.py from the tests folder_
I use `pytest-watcher`_ to run the tests automatically
terminal
```
uv run pytest-watcher . --now
```

extract test_microwave

RED: make it fail

I add a test with for loops for the sixteen cases

microwave/tests/test_microwave.py

class TestMicrowave(unittest.TestCase):

    def test_microwave(self):
        booleans = (False, True)
        for closed_door in booleans:
            for timer_set in booleans:
                for pressed_start in booleans:
                    for too_hot in booleans:
                        with self.subTest(
                            closed_door=closed_door,
                            timer_set=timer_set,
                            pressed_start=pressed_start,
                            too_hot=too_hot,
                        ):

microwave/tests/test_microwave.py

                            result = src.microwave.microwave(
                                closed_door=closed_door,
                                timer_set=timer_set,
                                pressed_start=pressed_start,
                                too_hot=too_hot,
                            )
                            self.assertEqual(result, 'BOOM!!!')

    def test_too_hot_w_timer_set_closed_door_pressed_start(self):

the terminal_ shows AssertionError for all sixteen cases.

GREEN: make it pass

I change self.assertEqual(result, 'BOOM!!!') to handle all the fifteen cases where the Microwave does NOT heat up food

microwave/tests/test_microwave.py

                            result = src.microwave.microwave(
                                closed_door=closed_door,
                                timer_set=timer_set,
                                pressed_start=pressed_start,
                                too_hot=too_hot,
                            )
                            self.assertFalse(result)

    def test_too_hot_w_timer_set_closed_door_pressed_start(self):

the terminal_ shows AttributeError for the one case where the Microwave will heat up food

I move the assertion into a try statement for it

microwave/tests/test_microwave.py

                            result = src.microwave.microwave(
                                closed_door=closed_door,
                                timer_set=timer_set,
                                pressed_start=pressed_start,
                                too_hot=too_hot,
                            )
                            try:
                                self.assertFalse(result)
                            except AssertionError:
                                self.assertTrue(result)

    def test_too_hot_w_timer_set_closed_door_pressed_start(self):

REFACTOR: make it better

I remove all the other tests because they are now covered by test_microwave

microwave/tests/test_microwave.py

                            try:
                                self.assertFalse(result)
                            except AssertionError:
                                self.assertTrue(result)


# Exceptions seen

I add a git_ commit message

terminal

git commit -am 'extract test_microwave'

close the project

I close tests/test_microwave.py
I click in the terminal_ where the tests are running
I use q on the keyboard to leave the tests
I `change directory`_ back to the parent of Microwave
terminal
```
cd ..
```

review

Another test with nested for loops, there has to be a better way

code from the chapter

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

what is next?

Would you like to test making a Car starter?

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