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Shift-Left Testing is transforming software development by encouraging testing toward the early stages of the Software Development Lifecycle (SDLC).  It follows the ethos of the “test early and often” maxim coined by Larry Smith in 2001, but has been in play since the 1950s in different forms. In this article we look at the basics of the Shift-Left Approach: What it is, Why it’s important for Developers, and What are its Best Practices.

The Essence of Shift-Left Testing

Shift-Left Testing fundamentally changes the traditional software development process. In a conventional model, the lifecycle of software development was seen as a linear progression:

Software Development Lifecycle (SDLC)

This often results in a ‘right-heavy’ approach where testing and security checks were crammed towards the end (i.e., the right-hand side) of the cycle, leading to increased costs, delayed time to market, and potential for errors​​​​.  Recognising the potential bottleneck here, Shift-Left approaches began to gain traction.

With Shift-Left Testing, the paradigm changes. Testing and security are integrated as early as possible in the SDLC i.e., towards the left. It requires building more automation, security, and networking features directly into the applications, so that the code of the application can orchestrate and automate infrastructure demands, including security, based on the application needs.

The aim is to identify and fix defects at the earliest stage, significantly reducing the cost and time required to address them later. For instance, vulnerabilities detected early in the development process might cost around $80 on average to fix, compared to a staggering $7,600 if discovered post-production​​ (Research from Ponemon Institute, 2017).

“By testing early and often, a project can reduce the number of bugs and increase the quality of the code.” –

Agile practices, almost universally adopted now, mandate this integration for more efficient and error-free development​​.

The Importance for Developers

In the Agile environment, the emphasis is on accelerating the pace of development. This necessitates shortening the delivery timeline while simultaneously enhancing the quality of each deployment. Concurrently, there’s a growing demand to minimize the expenses associated with testing.

Adopting Agile methodologies results in a diverse range of testers, each possessing unique expertise, participating in the testing phase. In particular, this approach integrates developers into the testing sequence much sooner than in traditional models.

For developers, Shift-Left Testing means embracing a mindset where quality and security are not afterthoughts but integral parts of the development process from the start. This approach allows teams to:

  • Test Continuously: Incorporate testing into the daily workflow, enabling early detection and resolution of issues​​.
  • Utilize Open-Source and Custom Tools: Developers have begun to create their own tools tailored to their needs, often opting for open-source options. This trend reflects a shift towards tools that are not just effective but also developer-friendly​​.
  • Improve Collaboration: A unified test strategy under the Shift-Left approach promotes collaboration among all stakeholders, ensuring that everyone is on the same page regarding quality and security standards​​.

It’s important to note however, that while Shift-Left Testing is transformative, it’s not a one-size-fits-all solution. In scenarios where Shift-Left may not deliver optimal performance, Shift-Right Testing comes into play. This approach involves testing post-production to enhance customer experience and provide better test coverage, leveraging user feedback to improve software quality​​​​.

Shift-Left Testing Best Practices

Shift-Left Testing is a no-brainer for many software development companies.  Improving code, increasing ROI and reducing risk are all things that are critical to success when ensuring quality and efficiency.  So lastly, we summarise some of the best practices to follow when adopting a shift-left test approach:

  1. Early Integration: Begin testing early in the software development life cycle. Align testing strategies with project planning to clarify objectives and outcomes.
  2. Maintain Quality Standards: Establish rigorous quality standards across all stages of the SDLC, ensuring development aligns with quality assurance requirements.
  3. Empower Testers with Coding Skills: Encourage testers to develop coding skills for deeper defect analysis and independent code adjustments.
  4. Continuous Feedback: Implement a continuous feedback loop between testers and developers for prompt defect resolution and quality maintenance.
  5. Testable Code Development: Motivate developers to write code with testability in mind, reducing testing time and ensuring quality from the onset.
  6. Leverage Test Automation: Adopt test automation to streamline the build-to-test process across the SDLC, boosting integration, continuous delivery, and confidence in each release.

By adopting these practices, technology companies can significantly enhance their software quality, delivering reliable and efficient products to the market.

We recently came across a great article from @rahull on “A Practical Guide to Shift Left Testing for Software Developers” that we highly recommend reading for more advice on this.


Shift-Left Testing represents a significant shift in how developers approach the building and securing of software. It’s about integrating testing and security into the very fabric of the development process, thereby reducing costs, improving efficiency, and enhancing the overall quality of software products. As technology evolves, so must our approaches to software development, with Shift-Left Testing playing a pivotal role in this evolution. For developers and organizations alike, understanding and implementing this strategy is not just beneficial but essential in the digital world.