how to make a python test driven development environment on Windows without Windows Subsystem for Linux

preview

This is one way to make a Python Test Driven Development project on a Windows Computer that does NOT have Windows Subsystem for Linux. I walk through making the folders (directories) and files for the environment, including setting up the first test

By the end of the chapter you will be know these commands better

mkdir
cd
touch
echo
cat
python -m venv .venv
.venv/scripts/activate
python -m pip install --upgrade pip
python -m pip install --requirement requirements.txt
pytest-watch
deactivate
history

questions about making a Python Test Driven Development Environment on Windows without Windows Subsystem for Linux

Here are questions you can answer after going through this chapter

what is a Test Driven Development Environment?
How can I make a Python Test Driven Development Environment manually?
How can I change directories?
How can I make a directory?
How can I see directory structure?
How can I make an empty file?
How can I write text to a file?
How can I change the name of a file?
How can I run a Python Program?
How can I test for failure?
How can I make a Python package?
How can I run tests manually?
How can I run tests automatically?
How can I stop automated Python tests from running?
What is a Virtual Environment?
How can I make a Virtual Environment?
How can I activate a Virtual Environment?
How can I deactivate a Virtual Environment?
How can I document the Python programs my project needs?
How can I install the Python programs my project needs from a file?
How can I install Python packages in a Virtual Environment?
How can I see what Python packages are installed in a Virtual Environment?
How can I view all the commands I type in a terminal?

requirements

download and install Python
get an Integrated Development Environment (IDE). Here are a few options

how to make a Python Test Driven Development environment manually on Windows without Windows Subsystem for Linux

I choose magic as the name for this project

I open Terminal in the menu bar at the top of the Integrated Development Environment (IDE), then click New Terminal to open a terminal
I change directory to where I will put all the projects from this book. I type cd in the terminal

Note

You can skip this step if you are already in the pumping_python directory
```
cd pumping_python
```
the terminal shows
```
cd: no such file or directory: pumping_python
```
the folder (directory) does NOT exist. I need to make it
I use the mkdir program to make the pumping_python folder (directory)
```
mkdir pumping_python
```

the terminal goes back to the command line

I try changing directory again
```
cd pumping_python
```
the terminal shows I am now in the pumping_python folder (directory)
```
...\pumping_python >
```
I type tree in the terminal to see what files and folders are in the pumping_python directory
```
tree /F
```
the terminal shows
```
C:.
No subfolders exist
```
Note

If you have done other work in the pumping_python folder there will be files and folders not 0 directories and 0 files

how to make a directory for the project on Windows without WSL

I change directory to the magic project in the pumping_python folder
```
cd magic
```
the terminal shows
```
cd: no such file or directory: magic
```
the magic folder does NOT exist yet
I make the magic directory
```
mkdir magic
```
this makes a folder (directory) for the project where its files will stay
I use tree again
```
tree /F
```
the terminal shows
```
.
└── magic
```

how to change directory to the project on Windows without WSL

I try cd again

cd magic
the terminal shows I am now in the magic folder I just made in the pumping_python folder
...\pumping_python\magic >

how to run a Python program on Windows without Windows Subsystem for Linux

I use Python to run the magic program

python src/magic.py

the terminal shows

python: can't open file '...\pumping_python\magic\src\magic.py': [Errno 2] No such file or directory

the computer cannot find the program because it does not exist, yet

how to make a directory for the source code on Windows without WSL

I make a child folder in the magic directory for the program
```
mkdir src
```
the terminal goes back to the command line
I use tree to see what changed in the magic directory
```
tree /F
```
the terminal shows
```
.
└── src
```
I try to run the magic program again
```
python src/magic.py
```
the terminal shows the same error from before. I have to make the file

how to make an empty file on Windows without Windows Subsystem for Linux

I use New-Item to make an empty file in the src folder
```
New-Item src/magic.py
```
the terminal goes back to the command line
I use tree to see what folders and files I now have
```
tree /F
```
the terminal shows
```
.
└── src
    └── magic.py
```
New-Item is a command that makes an empty file with the name. I can give it the directory I want to put the file in as part of the name, in this case New-Item src/magic.py makes a file named magic.py in the src folder
I try to run the magic program again
```
python src/magic.py
```
the terminal goes back to the command line. Success! Even though magic.py does not do anything because there is no code in it, I can successfully run it because it exists.

test_failure on Windows without WSL

how to manually run tests on Windows without WSL

I use the unittest module from the Python standard library that comes with Python to run tests. I type this in the terminal
```
python -m unittest
```
the terminal shows
```
----------------------------------------------------------------------
Ran 0 tests in 0.000s

NO TESTS RAN
```
- python is the Python program
- -m is an option/switch passed when calling Python to run the module, unittest in this case
- a Python module is any file that ends with .py, this means somewhere on the computer there is a file named unittest.py, see the source code for unittest here
I do not have any tests yet, so there is nothing to run

how to make a directory for the tests on Windows without WSL

I make a child folder to keep the tests separate from the actual program
```
mkdir tests
```

the terminal goes back to the command line

I use tree to see what my project looks like

tree /F

the terminal shows

.
├── src
│   └── magic.py
└── tests

how to make a Python file to hold the tests in the ‘tests’ folder on Windows without WSL

I use New-Item to add an empty file to the tests directory for the actual test
```
New-Item tests/magic.py
```
the terminal goes back to the command line

I use tree to see what the project looks like so far

tree /F

the terminal shows

.
├── src
│   └── magic.py
└── tests
    └── magic.py

I run the test again
```
python -m unittest
```
the terminal shows
```
NO TESTS RAN
```

RED: make it fail

I open tests/magic.py with the Integrated Development Environment (IDE) to open it in the editor
Tip

I can open a file from the terminal in Visual Studio Code by typing code and the name of the file with
```
code tests/magic.py
```
I can also open a file by using ctrl on the keyboard and clicking with the mouse on the name of the file
I add the Python code below in tests/magic.py in the editor

Note

the line numbers below are a guide, you do not need to copy them
```
1import unittest
2
3
4class TestMagic(unittest.TestCase):
5
6    def test_failure(self):
7        self.assertFalse(True)
```
Here is an explanation of the code I typed in the file
- import unittest imports the unittest module from the Python standard library, this is what I am using for testing
- class TestMagic
  - class is the Python keyword for making classes - a group of attributes (values) and methods (functions) that belong together, I cover this in more detail in the classes chapter
  - TestMagic is the name I gave this class and will hold the test
    
    Important
    
    I can use any name for the test class, it MUST start with Test or unittest will NOT run the tests in it
  - unittest.TestCase is a class from the unittest module that has methods for testing
  - class TestMagic(unittest.TestCase) defines TestMagic as a “child” of unittest.TestCase which means I can use its methods and attributes
- def test_failure
  - def is the Python keyword for making methods (functions), see functions for more
  - test_failure is the name I used method for this first test
    
    Important
    
    I can use any name for the test method, it MUST start with test_ or unittest does NOT run the tests in it
  - self. lets me use attributes and methods of the TestMagic class which is a “child” of the unittest.TestCase class, instead of using TestMagic(). or unittest.TestCase().
    
    Important
    
    the name self is Python convention. I can use any name but it is easier to stick with convention for this concept
  - self.assertFalse(True) is an assertion
    - assertFalse is a method in the unittest.TestCase class that checks if its input is False
    - True is given as the input
    I expect this line to fail because True is not False. If it does not fail, then Python and I have a problem
I turn on the Auto Save feature in the Integrated Development Environment (IDE) to automatically save files when I make a change so that I do not repeat myself by saving (ctrl+s (Windows/Linux) or command+s (mac)) every time I make a change

Attention

Turn on the Auto Save feature in your Integrated Development Environment (IDE)
I try the command again to run the tests in the terminal
```
python -m unittest
```
the terminal shows
```
NO TESTS RAN
```
I need to tell Python that the tests folder is a Python package, so it can find the tests

how to make the tests a Python package on Windows without WSL

I use New-Item to add an empty file with the name __init__.py in the tests folder

Attention

make sure to use 2 underscores (__) before and after init for __init__.py
```
New-Item tests/__init__.py
```
the terminal goes back to the command line

I run the tree command to see what changed

tree /F

the terminal shows

.
├── src
│   └── magic.py
└── tests
    ├── __init__.py
    └── magic.py

I try to run the tests again
```
python -m unittest
```
the terminal shows
```
NO TESTS RAN
```
I need to tell Python that magic.py in the tests folder is a test file
I close magic.py in the editor of the Integrated Development Environment (IDE)

Caution

if you do not close magic.py you will end up with 3 files in the tests folder after the next step (instead of 2), because the Auto Save feature (enabled earlier) will save the original file after you change its name

how to change the name of a file on Windows without WSL

I use the Move-Item command to change the name of magic.py in the tests folder to test_magic.py
```
Move-Item tests/magic.py tests/test_magic.py
```
the terminal goes back to the command line
I use tree to see what I have so far
```
tree /F
```
the terminal shows

Note

if you do not see __pycache__ in the list do not worry, the important thing is that you renamed magic.py to test_magic.py for unittest to find the test
```
.
├── src
│   └── magic.py
└── tests
    ├── __init__.py
    ├── __pycache__
    └── test_magic.py
```

I run the tests again

python -m unittest

the terminal shows AssertionError

F
=============================================================
FAIL: test_failure (tests.test_magic.TestMagic.test_failure)
-------------------------------------------------------------
Traceback (most recent call last):
  File "...pumping_python/magic/tests/test_magic.py", line 7, in test_failure
    self.assertFalse(True)
    ~~~~~~~~~~~~~~~~^^^^^^
AssertionError: True is not false

-------------------------------------------------------------
Ran 1 test in A.XYZs

FAILED (failures=1)

Important

I can use any name for the test file but it must start with test_ or unittest will NOT run the tests in the file

This is the RED part of the Test Driven Development cycle. The message in the terminal is about the failure, I like to read these from the bottom up, here is an explanation of each line, starting from the last line on the screen
- FAILED (failures=1) the number of failures
- Ran 1 test in A.XYZs the number of tests it ran and how long they took
- AssertionError: True is not false the Error (Exception) that happened and its message, in this case AssertionError because True is not False
- self.assertFalse(True) the line of code that caused AssertionError
- ~~~~~~~~~~~~~~~~^^^^^^ points to the part of the line above that Python thinks caused the error
- File ".../magic/tests/test_magic.py", line 7, in test_failure the line number of the code that caused the error and the location of the file where it is
- Traceback (most recent call last): all the information shown after this line that is indented to the right shows the calls that led to the failure, this is why I like to read it from the bottom up
- FAIL: test_failure (tests.test_magic.TestMagic.test_failure) is a header with information in dot notation about the failing test method
  - tests.test_magic.TestMagic.test_failure is the location of the failing test
  - tests is the tests folder
  - test_magic is the test_magic.py file in the tests directory
  - TestMagic is the class defined on line 4 in test_magic.py
  - test_failure is the method (function) defined on line 6 in test_magic.py
- F shows a failure
I hold ctrl on the keyboard and use the mouse to click on File ".../pumping_python/magic/tests/test_magic.py", line 7 in the terminal, and the Integrated Development Environment (IDE) opens the file in the editor with the cursor at the line where the failure happened

GREEN: make it pass

I change True to False on line 7 of test_magic.py in the editor

        self.assertFalse(False)

I run the test again in the terminal

python -m unittest

the test passes! The terminal shows

.
------------------------------------------------------
Ran 1 test in A.XYZs

OK

cue CELEBRATION MUSIC AND DANCE! I am GREEN!!

REFACTOR: make it better

Keep a list of Errors/Exceptions that show up in the terminal as you go through this book to know them better, it helps when you run into them later. I add a list with AssertionError in test_magic.py in the editor

import unittest

class TestMagic(unittest.TestCase):

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

# Exceptions seen
# AssertionError

I ran python -m unittest a few times to see the test fail, I ran python -m unittest again to see the test pass. I will have to run python -m unittest again when I add any code, to make sure tests that were passing do not start failing and that the new code I add does what I want.

This means I have to run python -m unittest for each part of the Test Driven Development cycle or any time there is a code change.

I do not want to type python -m unittest again, it is better for a computer program to run the tests so that I do not repeat myself.

how to run the tests automatically on Windows without Windows Subsystem for Linux

I can use pytest-watch to run tests automatically. It is a Python program that automatically runs pytest any time a Python file changes in the folder it is looking at, this means it will run the tests for me every time I make a change.

pytest is a Python package like unittest, it is not part of the Python standard library

I type it in the terminal

pytest-watch

the terminal shows

command not found: pytest-watch

I need to install pytest-watch for the computer to use it. Next, I set up a virtual environment to keep programs my project needs in one place

what is a virtual environment?

I can install pytest-watch globally (for the entire computer), which means it will always be available to any project on the computer, but a better way would be to put it in a virtual environment so that it is installed only for this project.

A virtual environment is a separate folder where I can install Python packages that my project needs. This helps me keep things that belong to the project in one place, separate from other things on the computer.

It means I can have a separate virtual environment for every project with only the programs that the project needs. This helps if I decide to package the program to send to someone else, because everything needed by the project is in one place.

how to make a virtual environment on Windows without WSL

I make a virtual environment with the venv module from the Python standard library
```
python -m venv .venv
```
the terminal goes back to the command line
- python is the Python program
- -m is an option passed to Python to run the module given after the option
- venv is a module from the Python standard library, it is used to make a virtual environment with a given name
- .venv is the name I am giving for this virtual environment
  
  Important
  
  .venv is Python convention, I can use any name I want for the virtual environment

I run tree

tree /F

the terminal shows

.
├── src
│   └── magic.py
├── tests
│   ├── __init__.py
│   ├── __pycache__
│   └── test_magic.py
└── .venv
    ├── bin
    ├── .gitignore
    ├── include
    ├── lib
    ├── lib64 -> lib
    └── pyvenv.cfg

there is now a folder named .venv for the virtual environment

how to activate a virtual environment on Windows without WSL

I run PowerShell in Administrator mode and set the Execution Policy for the activation script to work

Set-ExecutionPolicy RemoteSigned

the terminal may show the following message if you have never run this command before

The execution policy helps protect you from scripts that you do not trust.
Changing the execution policy might expose you to the security risks
described in the about_Execution_Policies help topic at
https:/go.microsoft.com/fwlink/?LinkID=135170.
Would you like to change the execution policy?

[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (default is "N"):

Type A to accept the change and it enables scripts that have been signed by a verified publisher to run on your computer, you can read more at Set-ExecutionPolicy

When I want to work in a virtual environment, I make sure I am in the parent directory of it, for example, magic in this case. I activate the virtual environment in the terminal to use it
```
.venv/scripts/activate.ps1
```
the terminal shows
(.venv) .../magic $
the (.venv) on the far left of the command line in the terminal shows that I am in the virtual environment
I use pytest-watch to run the test again
```
pytest-watch
```
the terminal shows
```
command not found: pytest-watch
```
I have to install pytest-watch in the virtual environment to use it in the virtual environment

how to see what packages are installed in a virtual environment on Windows without WSL

I use the Python package manager (pip) to see what Python packages are installed in the virtual environment I just made

pip list

the terminal shows

Package Version
------- -------
pip     x.y

pytest-watch is not in the list
pip is a module from the Python standard library, it is used to install Python packages

how to write text to a file on Windows without Windows Subsystem for Linux

I want to make a file where I can list all the Python packages for my project as a way to document it and have pip install the programs listed in the file

I can write text to a file with the echo program, it shows whatever it is given as an argument, on the screen (standard output (stdout)) for example
```
echo "pytest-watch"
```
the terminal shows
```
pytest-watch
```
I can use it to write text to a file by giving the file name with an operator
```
echo "pytest-watch" > requirements.txt
```
> is an operator that is used to send output from a program to the given file
I can also use Out-File to add text to a file, I use it to make the requirements file with pytest-watch as its text
```
"pytest-watch" | Out-File requirements.txt
```
- | is an operator that is used to send output to a program
- Out-File is a program that can be used to write text to a file
- pytest-watch is a Python program that automatically runs pytest when a Python file in the folder changes
- pytest is a Python package like unittest, that is used for testing
- requirements.txt is the name of a file where I can list Python packages for pip to install. The name requirements.txt is Python convention, I can use any name I want for the requirements file

I run tree to see what the project looks like now

tree /F

the terminal shows

.
├── requirements.txt
├── src
│   └── magic.py
├── tests
│   ├── __init__.py
│   ├── __pycache__
│   └── test_magic.py
└── .venv
    ├── bin
    ├── .gitignore
    ├── include
    ├── lib
    ├── lib64 -> lib
    └── pyvenv.cfg

requirements.txt is now in the magic folder

how to see what is inside a file on Windows without WSL

I can use the cat program to see what is inside a file. I use it to make sure my requirements.txt has pytest-watch inside it

cat requirements.txt

the terminal shows

pytest-watch

life is good!

how to install Python packages in a virtual environment on Windows without WSL

I use pip to install pytest-watch from the requirements file
```
python -m pip install --requirement requirements.txt
```
- --requirement is an option that can be passed to the install argument for Python packages in a given file
- requirements.txt is the name of the given file
the terminal shows programs being downloaded and installed, and when I do not have the latest version of pip installed, it shows this at the end
```
[notice] A new release of pip is available: XY.Z -> AB.C
[notice] To update, run: pip install --upgrade pip
```

how to upgrade the Python package manager in a virtual environment on Windows without WSL

I upgrade pip to the latest version. I recommend you do this every time you are in a virtual environment, it is good practice to update package managers to the latest version available
```
python -m pip install --upgrade pip
```
- install is an argument given to pip to install a given Python package
- --upgrade is an option that can be passed to the install argument, like --requirement from earlier, this one tells pip to upgrade the version of the given Python package
- pip is the Python package I am giving pip to install, in this case it upgrades itself to the latest version since I did not give a version number
Note

I can also tell pip to install pytest-watch directly without using a requirements file, the problem is it will not document what programs my project needs. I would either have to remember later or use pip list. It also does not help someone else who is trying to run my project later, know what programs it needs without me
```
python -m pip install pytest-watch
```
I check what Python packages are now installed in the virtual environment
```
pip list
```
the terminal shows
```
Package      Version
------------ -------
colorama     x.y.z
docopt       x.y.z
iniconfig    x.y.z
packaging    x.y
pip          x.y
pluggy       x.y.z
Pygments     x.y.z
pytest       x.y.z
pytest-watch x.y.z
watchdog     x.y.z
```
pytest-watch is in the list. Yes!

Tip

imagine that the pytest-watch project also has a requirements file with colorama, docopt, iniconfig, packaging, pluggy, Pygments, pytest and watchdog as programs that it needs to run and they got installed when I asked pip to install pytest-watch from the requirements.txt file

how to run the tests automatically in a virtual environment

I try to run the tests again

pytest-watch

and it shows results without going back to the command line

================== test session starts===================
...
rootdir: .../magic
collected 1 item

tests/test_magic.py .                              [100%]

=============== 1 passed in X.YZs =======================

how to open the test file in the editor from the terminal on Windows without WSL

I hold ctrl on the keyboard and click on tests/test_magic.py to place the cursor in the editor of the Integrated Development Environment (IDE), then I change False to True on line 7

      self.assertFalse(True)

the terminal shows AssertionError

====================================== FAILURES =======================================
_______________________________ TestMagic.test_failure ________________________________

self = <tests.test_magic.TestMagic testMethod=test_failure>

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

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

I hold ctrl on the keyboard and click on tests/test_magic.py:7 to place the cursor in the editor of the Integrated Development Environment (IDE), then I change True back to False in test_magic.py

      self.assertFalse(False)

the test passes and I can write the rest of the code for the project as the tests run automatically in response to any change I make

how to stop the automated tests on Windows without WSL

I exit the tests in the terminal with ctrl+c on the keyboard

how to deactivate a virtual environment on Windows without WSL

I leave the virtual environment by typing this in the terminal
```
deactivate
```
the terminal goes back to the command line, (.venv) is no longer on the left side
```
...\pumping_python\magic
```
I try pytest-watch again to show that I do not have it installed outside the virtual environment
```
pytest-watch
```
the terminal shows
```
command not found: pytest-watch
```
I change directory to the parent of magic
```
cd ..
```
.. is shorthand for the parent of any directory you are in. The terminal shows
```
...\pumping_python >
```
I am back in the pumping_python folder

review

I gave the computer some commands to make a Python Test Driven Development environment. I made some folders and files, successfully wrote a failing test, made it pass, then made the tests run automatically

how to view all the commands I typed in a terminal on Windows without WSL

I type history in the terminal to see all the commands I have typed so far

history

the terminal shows

cd pumping_python
mkdir pumping_python
cd pumping_python
tree /F
cd magic
mkdir magic
tree /F
cd magic
python src/magic.py
mkdir src
tree /F
python src/magic.py
New-Item src/magic.py
tree /F
python src/magic.py
python -m unittest
mkdir tests
tree /F
New-Item tests/magic.py
tree /F
python -m unittest
New-Item tests/__init__.py
tree /F
python -m unittest
mv tests/magic.py tests/test_magic.py
tree /F
python -m unittest
pytest-watch
python -m venv .venv
tree /F
tree /F
.venv/scripts/activate.ps1
pytest-watch
pip list
echo "pytest-watch"
echo "pytest-watch" > requirements.txt
"pytest-watch" | Out-File requirements.txt -Encoding UTF8
tree /F
python -m pip install --requirement requirements.txt
python -m pip install --upgrade pip
pip list
pytest-watch
deactivate
pytest-watch
cd ..
New-Item makePythonTdd.ps1
tree /F

the history program shows all the commands I typed in the terminal so far, and I use them to write the program that will automatically make a Python Test Driven Development environment for me

these are the commands I used to help make a Python Test Driven Development environment

mkdir NAME_OF_THE_PROJECT
cd NAME_OF_THE_PROJECT
mkdir src
New-Item src/NAME_OF_THE_PROJECT.py
mkdir tests
New-Item tests/__init__.py
New-Item tests/test_NAME_OF_THE_PROJECT.py
python3 -m venv .venv
source .venv/bin/activate
echo "pytest-watch" > requirements.txt
python3 -m pip install --upgrade pip
python3 -m pip install --requirement requirements.txt
pytest-watch

where NAME_OF_THE_PROJECT is the name I give the project

these are the steps I took to make a Python Test Driven Development environment

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

what is next?

You have seen me make a Test Driven Development environment for a project called magic on any Windows computer that does NOT have Windows Subsystem for Linux. Would you like to test AssertionError next?

rate pumping python

If this has been a 7 star experience for you, please leave a 5 star review. It helps other people get into the book too

how to make a python test driven development environment

AssertionError