Shift Left Testing

What Does Shift Left Testing Mean?

Shift left testing is a DevOps principle that reduces technical debt by identifying and fixing bugs in every stage of the software development lifecycle (SDLC). The term is often associated with Agile software development and the phrase "test early and test often."


In project management, the term shift-left means that a task should be completed towards the beginning of the project and shift-right means it should be completed towards end of the project.

In software development, shift left supports automated testing and plays an important role in DevSecOps. The concept may also be referred to as continuous testing or incremental security testing.

Techopedia Explains Shift Left Testing

Shift-left testing has proven very efficient for software development teams, especially those engaged in Agile software development. It can speed up the development process and ensure higher confidence in the quality for software releases and application programming interfaces (APIs).

Traditional software development is often viewed in left-to-right stages:

Develop Application> Test Application> Deploy Application

In waterfall development, for example, the testing stage takes place after development has been completed. In this traditional approach to building software products, when coding errors (bugs) are identified in the testing stage, they are sent back to the developers to correct. The fixed code is then sent back to the quality assurance (QA) testing team and the back-and-forth process is repeated until the software is error-free and ready for deployment.

Importance of Shift Left Testing

Today, greater demand for frequent code releases has led to growing popularity of microservices and a push for quality assurance tests to be automatically carried out on unit tests. Testing earlier in the software development lifecycle allows project teams to identify and isolate errors quickly and fix them faster.

This shift in workflow, which reduces the back-and-forth between the QA and development teams, not only speeds up the entire development process, it also encourages the entire project team to prioritize security at each step of the project.

Shift-left testing has its own challenges, however. When project teams are asked to test their code as early as possible, developers have to:

Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…