how to make a Python Test Driven Development environment automatically

preview

Here is the program I have by the end of the chapter to automatically make a python test driven development environment, it is only 27 lines of code, with spaces

#!/bin/bash
mkdir more_magic
cd more_magic
mkdir src
touch src/more_magic.py
mkdir tests
touch tests/__init__.py

echo "import unittest


class TestMoreMagic(unittest.TestCase):

    def test_failure(self):
        self.assertFalse(True)


# Exceptions seen
# AssertionError
" > tests/test_more_magic.py

echo "pytest" > requirements.txt
echo "pytest-watcher" >> requirements.txt
uv init
rm main.py
uv add --requirement requirements.txt
uv run pytest-watcher . --now

questions about making a Python Test Driven Development Environment automatically

Here are questions you can answer after going through this chapter

how can I make a shell script?
how can I view the permissions of a file?
how can I make a shell script run as a command
how can I run a shell script

how to make a shell script

I go to the terminal and use touch to make an empty file with a name that is easy to remember later. I want the name to also describe the program that will automatically make a Test Driven Development environment for me
```
touch makePythonTdd.sh
```
the terminal goes back to the command line
I name this project magic_again
I open makePythonTdd.sh 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 makePythonTdd.sh
```
Visual Studio Code opens makePythonTdd.sh in the editor

I add the commands I use to make a Python Test Driven Development environment for a project in makePythonTdd.sh

#!/bin/bash
mkdir magic_again
cd magic_again
mkdir src
touch src/magic_again.py
mkdir tests
touch tests/__init__.py
touch tests/test_magic_again.py
echo "pytest" > requirements.txt
echo "pytest-watcher" >> requirements.txt
uv init
rm main.py
uv add --requirement requirements.txt
uv run pytest-watcher . --now

#!/bin/bash is called a shebang line, it tells the computer to use bash to run this program

test_magic_again.py is empty because I made it with touch. I want the file to have the text for the first failing test so I do not have to open the editor to add the text for it in each project.

I use echo in place of touch to make the makePythonTdd.sh program add the text to test_magic_again.py when it makes the file in the tests folder, the same way I use echo to add text to the requirements.txt file

#!/bin/bash
mkdir magic_again
cd magic_again
mkdir src
touch src/magic_again.py
mkdir tests
touch tests/__init__.py
echo "" > tests/test_magic_again.py
echo "pytest" > requirements.txt
echo "pytest-watcher" >> requirements.txt
uv init
rm main.py
uv add --requirement requirements.txt
uv run pytest-watcher . --now

I add the text for the the first failing test inside the quotes (“”) I just added to makePythonTdd.sh, the way I do with echo when I add "pytest" as text in requirements.txt

Attention

Indentation is important in Python, I use 4 spaces as convention in this book, see the Python Style Guide for more

#!/bin/bash
mkdir magic_again
cd magic_again
mkdir src
touch src/magic_again.py
mkdir tests
touch tests/__init__.py

echo "import unittest


class TestMagicAgain(unittest.TestCase):

    def test_failure(self):
        self.assertFalse(True)


# Exceptions seen
# AssertionError
" > tests/test_magic_again.py

echo "pytest" > requirements.txt
echo "pytest-watcher" >> requirements.txt
uv init
rm main.py
uv add --requirement requirements.txt
uv run pytest-watcher . --now

how to run a shell script

I go back to the terminal to run the program

makePythonTdd.sh

the terminal shows

command not found: makePythonTdd.sh

I have to tell the computer where the file is

./makePythonTdd.sh

./ is shorthand for this directory which in this case is pumping_python where makePythonTdd.sh is saved. The computer checks a few directories when a command is given. Those directories are where commands like mkdir, cd, tree and echo are saved. The terminal shows

permission denied: ./makePythonTdd.sh

I have to make the file executable for the computer to be be able to run the program.

how to view the permissions of a file

I use ls to check the permissions of the file

ls -l makePythonTdd.sh

-l is the option to show the long listing format which includes permissions for the file

the terminal shows

-rw-r--r-- 1 abcdef ghijk XX Month  Y ZA:BC makePythonTdd.sh

Note

the first 10 characters above (-rw-r--r--) are grouped

-    rw-    r--    r--

the groups that have 3 characters show read, write and execute permissions with

r for can read
w for can write to, and
x for can execute
- for CANNOT

here is what it means for makePythonTdd.sh

the first group with just 1 character tells if this is a file or directory : - means this is a file, it is NOT a directory
the second group has 3 characters, and is for the owner of the file: rw- means the owner of the file can read (r), write to (w), and CANNOT (-) execute the file
the next group also has 3 characters, and is for the group of the owner of the file: r-- means the group can read (r), CANNOT (-) write to, and CANNOT (-) execute the file
the last group has 3 characters and is for other users: r-- means other users can read (r), CANNOT (-) write to, and CANNOT (-) execute the file

I want to add execute permissions so I can run (execute) the file

how to make a shell script run as a command

I change the mode of the file to add executable permissions
```
chmod +x makePythonTdd.sh
```
chmod is a program that changes the mode (permissions) of the given file, the terminal goes back to the command line
I list the permissions again with ls
```
ls -l makePythonTdd.sh
```
the terminal shows
```
-rwxr-xr-x 1 abcdef ghijk XX Month  Y ZA:BC makePythonTdd.sh
```
Note
- - means this is a file, it is NOT a directory
- rwx means the owner of the file can read (r), write to (w) and execute (x) the file
- r-x means the group of the owner of the file can read (r), CANNOT (-) write to, and can execute (x) the file
- and the second r-x means other users can read (r), CANNOT (-) write to, and can execute (x) the file

I try the command again

./makePythonTdd.sh

the terminal shows

============================== FAILURES ===============================
____________________ TestMagicAgain.test_failure ______________________

self = <tests.test_magic_again.TestMagicAgain testMethod=test_failure>

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

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

Success! I just made a program that can make the magic_again project anytime I want and it automatically does the steps I used to do.

I hold ctrl on the keyboard and click on tests/test_magic_again.py to open it in the editor then make the test pass
I click in the terminal and use q on the keyboard to leave the tests, the terminal shows
```
.../pumping_python
```
I am back in the pumping_python directory
I close test_magic_again in the editor

I want to use makePythonTdd.sh to make another project with a different name. I change magic_again to the name of the new project in the editor

Note

The lines that are changing in the code are highlighted

#!/bin/bash
mkdir more_magic
cd more_magic
mkdir src
touch src/more_magic.py
mkdir tests
touch tests/__init__.py

echo "import unittest


class TestMoreMagic(unittest.TestCase):

    def test_failure(self):
        self.assertFalse(True)


# Exceptions seen
# AssertionError
" > tests/test_more_magic.py

echo "pytest" > requirements.txt
echo "pytest-watcher" >> requirements.txt
uv init
rm main.py
uv add --requirement requirements.txt
uv run pytest-watcher . --now

I run makePythonTdd.sh in the terminal to make a project named more_magic

./makePythonTdd.sh

the terminal shows AssertionError

============================== FAILURES ===============================
_____________________ TestMoreMagic.test_failure ______________________

self = <tests.test_more_magic.TestMoreMagic testMethod=test_failure>

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

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

I make the test pass

I click in the terminal and use q on the keyboard to leave the tests, the terminal shows
```
.../pumping_python
```
I am back in the pumping_python directory
I close test_more_magic.py in the editor

makePythonTdd.sh works and can automatically make a Python Test Driven Development environment the way I want every time. What a beautiful life.

review

Computer Programming allows me to take some steps and make them a one line command for the computer to do for me. You have seen a way I can make a Python Test Driven Development environment, with a program to do it on any Linux, Windows or MacOS computers.

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 have gone through a few things

Would you like to use makePythonTdd.sh to make a Python Test Driven Development environment to test that an Exception is raised?

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