Tag Archives: shift-left

Shift Left

Note: This article was originally written for my blog in Portuguese back in 2021.

Shift Left is a practice in software development where the aim is to find defects as early in the process as possible. A study from NIST shows that the cost of finding and fixing defects increases exponentially the farther it is found in the development cycle. Therefore, the ideal scenario is to find defects as early as possible, ideally in the design phase.

As a DevOps professional, a large part of my work has been focused on code quality in our business unit, which primarily develops code for embedded systems, FPGAs, industrial automation, and industrial robot controllers. Given the nature of our products, the cost of developing high-quality code is immense, and each release cycle is exceptionally long.

To solve these problems, our team has been working to implement a Shift Left approach by following these steps:

Writing Unit Tests Concurrently with Code

Writing unit tests concurrently with the code is the most critical part of Shift Left. Developers should not wait for the next phase, testing, to see if there are any obvious bugs in the code. Instead, most testing should be done in the implementation phase through unit tests that must be run constantly. This also helps ease the test team’s workload and lets them focus on more important things than testing the basics.

Code Review

The next step is code review. Developers should create a branch, write the code (including tests), and send it for review instead of merging it directly into the trunk. Code review allows for the early detection of bugs and can prevent these issues from propagating to later stages of development, saving time and resources. Code review allows developers to learn from one another and share best practices, resulting in better code quality and more effective teamwork, again addressing them on the left. See Google’s best practices for code review.


Human beings don’t like to have their work criticized, so pre-commit hooks can reduce criticism’s human element. Using pre-commit, a bunch of tests can be pre-programmed to run in the code about to be committed. Linters, tools that check for leaking secrets, styling tools, and others can be used. Pre-commit does not allow code to be pushed if it does not pass QA on the developer’s machine. It ensures that the basics are covered before the code goes into review.

Text Editor and Plugins

The text editor/IDE that the developer uses is as far left as possible. Developers can use various plugins and tools to improve the code. For instance, Microsoft Visual Studio Code is an excellent editor with many useful plugins, including language servers, linters, and AI-based plugins like Co-pilot, Sourcery and TabNine. Sonarlint, a Sonarqube plugin, can analyze code and display issues as soon as the user saves it.

By following the steps outlined above, software development teams can significantly reduce the number of defects that make it to the testing phase. While no single solution guarantees perfect code, combining the tools and techniques discussed and a strong focus on code quality can help minimize the total project delivery cost and time. For further information on how these steps can help reduce defects and improve the overall quality of code, I strongly recommend reading Steve McConnell’s book Code Complete. Take action today to improve your software development process and achieve better outcomes for your team and business.