Marvelous MLOps #25: How to test ML code?

Just like how we check if small parts of our code work (unit testing) or if different parts work well together (integration testing) in software applications, we can write similar tests for our machine learning code base. This helps us make sure our ML code is correct, trustworthy, and robust.

ML models are affected by lots of things, the data they use, how the data is prepared, and the algorithms they’re based on. When we test the code properly, we can find mistakes early on while we’re building, making sure everything works as expected and the code stays good as the project grows.

In this article, I’d like to give you some ideas on when and how to write tests for ML code.

Installing pytest

A popular testing framework in Python is pytest. You can install it using the following command:

pip install pytest        

More resources on pytest are provided at the end of the article.

Repository Overview

The code snippets are extracted from the movie-recommender repository, where a basic recommender algorithm is implemented.

movie-recommender/
│
├── data/     #Contains the movie ratings dataset
│   └── ratings.csv
│
├── topn/
│   │
│   ├── preprocess/ #Handles data cleaning
│   │   └── proprecessor.py
│   │ 
│   ├── model/      #Recommender algorithm
│   │   └── recommender.py
│   │
│   ├── evaluation/ #Evalution functions
│   │   └── evaluator.py
│   │
│   └── utils/
│       └── helper.py
│
├── tests/   #Holds tests for preprocessor and recommender modules
│    │
│    ├── test_preprocessor.py
│    ├── test_preprocessor.py
│    └── test_evaluator.py
│  
├── setup.py
├── main.py  #Main execution file
├── .gitignore.py
│
└── README.md        

For testing, it is best to adopt Object-Oriented Programming (OOP) best practices and design your codebase in a modular manner. This approach will simplify the process of writing both unit and integration tests.

Read further on our Substack: https://open.substack.com/pub/marvelousmlops/p/how-to-test-ml-code?r=w50g&utm_campaign=post&utm_medium=web