Leveraging pytest

00:00 So far, you’ve actually just worked with the workflow files and besides the README file, there is not much going on in your repo. So in this lesson, you’ll create a small Python script, freeze the requirements for your project, and write a test for your project.

00:16 Head over to your editor and create a new file named hello.py. Inside this file, create a function greet with the parameter person.

00:25 And this function should return an f-string saying Hello and then in curly braces person. When you execute this file directly, then you want to call the greet() function.

00:35 So below the function definition, add if __name__ == "__main__": And then create a print() function call passing a greet() function call with the argument.

00:47 For example, Chris, which is a very nice name.

00:51 Now, depending on your Python expertise, this file is very basic, but I don’t want to overcomplicate the Python within this course, so you can transfer the pattern conveniently to your own code if you want.

01:04 Before continuing, open the terminal and execute the hello.py file. As you can see, it says Hello, Chris! Perfect. So next, create a virtual environment and install pytest with python -m venv venv/,

01:22 and then activate the virtual environment with

01:28 source venv/bin/activate. And once the virtual environment is activated, you can install pytest with python -m pip install pytest.

01:43 Since pytest is a dev dependency, it’s a good idea to save it in a requirements file specifically for your dev requirements. python -m pip freeze and then the greater sign, so you’re writing the output in a file, and as a file you can choose requirements_ dev.txt.

02:07 This part is important because later in your GitHub Action you will use this requirements file to install any requirements that a GitHub Action needs. Alright, and now with pytest in place, create a new file named test_hello.py.

02:25 In the file, import pytest, and then from hello import greet.

02:35 And then the test function, test_greeting(),

02:39 assert greet( and as an argument, let’s choose Tappan, which is also a very nice name, == "Hello, Tappan!" Because when we’re calling the greet() function and passing in the name Tappan, we expect the output Hello, Tappan! Okay, perfect.

02:55 So let’s see if the test passes. Hop over to the terminal and run pytest. And as you can see, a green dot, so the test worked, everything is fine, and then you can commit your changes.

03:10 There is no need to push right now because the next part is to create a GitHub workflow first, and then we can push afterward.