Testing a socketio Web App written in Python

In this article I will show you how you can test an async Socketio application in Python, where the ASGI server we are running is uvicorn. I will be referring to these tests as integration tests, though depending on who you ask they could be called E2E tests, system tests, slow test etc. What I am referring to is simply testing out the entire “flow” of a socketio event i.e. emitting an event from a client, then receiving it on the web service and for my actual projects interacting with an actual database....

What does yield do in Python

In this article, we will go over what the yield keyword is used for. We will also cover how you can use a yield with a pytest fixture to allow us to “teardown” tests, after all of our tests have run. A common job being removing test data from the database, so that next time your run the tests your tests won’t fail. Due to the database being in a different (unexpected) state....

How to use Gitlab CI, Pytest and docker-compose together

On a recent project, I was working on, I wanted to test my web service using docker-compose where I can run and kill Docker containers used by the application and see how my web application reacts to that. In this article, we will go over how you start docker containers using docker-compose from within Gitlab CI. The diagram above is a visualisation of what we are trying to achieve. We want to spawn Docker containers using docker-compose from within our job....

Testing a Connexion/Flask Application with Pytest

In this article, I will show you how you can test a Python web service that was built using Connexion (a wrapper library around Flask). We will go over how you can mock functions and how you can test your endpoints. There are two related articles I have written in the past listed below. In the first one we go over how to create a web service using Connexions, the same web service we will in this article....

Testing a Flask App with pytest-mock and pytest-flask

Pytest is a popular Python library used for testing. It is my preferred testing library because it requires less boilerplate code than the alternatives such as (the builtin) unittest, the built in testing library. In this article, I will show you how you can use pytest-flask and pytest-mock to test your Flask app. These two libraries are plugins for Pytest which build upon some of the features that Pytest provides us....

Pytest with Background Thread Fixtures

Recently I had to test some of my Python 🐍 🐍 🐍 code which required an external dependency and communicating by using TCP sockets 🔌 . You can think of this dependency as essentially a database because it stored information. However, when testing my Python code, I couldn’t rely on there always being a TCP server to send messages to. So I ended up creating a simplified mocked version in Python....