Shift-Left Testing: What It Is and Why It Matters

In the dynamic world of software development, delivering high-quality products is critical. Software testing is a key part of this process. It serves as the quality and reliability gatekeeper.

However, the traditional approach of testing at the end of the development cycle could be more efficient. Shift-left testing ensures testing earlier in the development process. This method improves team collaboration and overall software quality.

In this article, we will explore:

1. Testing types and the shift-left testing approach
2. Shift-left testing models and benefits
3. Implementing shift-left testing and understanding challenges

Testing types

The evaluation of software quality, functionality, performance, and reliability through software testing is a vital step in the software development process. It plays a crucial role in ensuring that the software produced is of superior quality.

But before we dive deep into the shift-left testing approach, let’s quickly review the testing types:

• Unit testing. Checking individual units or components of the software, including functions, methods, or classes.
• Integration testing and system-level testing. Verifying if different parts of a system and the whole system, respectively, work well together.
• Acceptance testing. It’s a broader term including User acceptance and operational readiness testing.
• Performance testing. Checking how well the software works under various load conditions, assessing speed, stability, and responsiveness.
• Penetration testing. Estimating the security of networks, systems, and web applications.
• Regression testing. Checking if features and functions that were already tested still work correctly.
• Static testing. Analyzing the source code without executing it.
• Visual testing. Verifying the visual aspects of the software, such as user interfaces (UI), layout, and design.

Now that we have covered the basics, let’s explore why the traditional waterfall development model is obsolete in the modern software delivery process and how agile pathed the way to the new testing age.

Tests in waterfall vs. agile

In the waterfall model, each development phase was done sequentially. That meant testers (or developers performing tests) needed to wait their turn. And that turn was right before deployment. It might seem obvious, but it led to delays in identifying issues. That often translated to software failures and questionable software quality. Testing in this model was also characterized by limited collaboration and loads of documentation.

The agile approach changed the entire software development process. Agile is a flexible and collaborative approach to software development that prioritizes delivering functional software early on. It involves working closely with customers and being able to adapt to changing requirements throughout the development process.

It also created a mindset change that led to continuous and shift-left testing.

What is shift-left testing?

In a nutshell, traditional shift-left testing involves shifting testing earlier in the development process. This helps find and fix problems early in the development, which saves time and money later. The name comes from the process of shifting testing to the beginning, as we (in most languages) start to write from the left.

Incremental shift-left testing is often applied to large-scale software projects. Testing is performed in each increment. Usually, as a piece of software that is delivered to a client.

Agile shift-left testing expanded on that idea. It incorporates testing in the agile methodology. 

As a result, we have a model that is characterized by:

• Continuous testing and integration. This ensures that tests are automated, run frequently, and provide rapid feedback on the software's quality.
• Collaborative approach. Testers and developers work closely to ensure testing is part of the development process.
• Empowerment of a cross-functional team. Testers are involved in all stages of software development to encourage their active participation.

The model-based shift-left testing is the fourth approach to shift-left testing developed since the term was first coined in 2001 by Larry Smith. Testers create and maintain models that show how software should work. These models are used to test executable requirements, architecture, and design models.

Benefits of shift-left testing

As a project manager, tester, or testing team leader, you know the importance of quality assurance. So now, let’s get into more detail about the benefits of shift-left testing and why you should consider implementing it in your projects or company as a whole.

Efficient development lifecycle

“Test early, test often” is the official mantra behind shift-left testing. Testing during earlier stages is, first and foremost, efficient. Bugs or defects identified early can be fixed before the code is merged into the main development branch. After that happens, running tests is more time-consuming because of the larger amount of code. This is especially important for functional bugs, integration problems, and performance bottlenecks.

Thanks to that ability to respond quickly to any issues in the code, the overall quality of the software improves. This, in turn, translates to faster time-to-market because testers and developers can work in parallel, reducing idle time. All this improves your bottom line or the ROI of your commissioned project.

Enhanced collaboration

Shift-left testing encourages cooperation among developers, testers, and other stakeholders during the software development life cycle. Testers work closely with developers to provide feedback and identify risks to ensure high-quality software.

Thanks to this close collaboration, the continuous feedback loop is shortened. This iterative feedback loop promotes agility and accelerates the software delivery timeline.

Implementing shift-left testing

Let's now focus on how to implement shift-left testing in your organization. We'll discuss various tools and technologies that can help companies move testing activities to earlier stages of software development. We will also look at how automation can improve efficiency, accuracy, and scalability in the testing process.

Tools facilitating shift-left testing

There are many tools you can leverage when working in a shift-left approach. These include the following:

• Continuous Integration/Continuous Delivery tools, like Jenkins, and GitLab CI/CD, facilitate the automation and can integrate testing into the development pipeline.
• Version Control systems, like Git, facilitate automated testing by allowing tests to run on various branches or commits.
• Test management tools, like TestRail or Zephyr, are a centralized platform for test case management, test coverage analysis, and defect tracking, facilitating efficient shift-left testing.
• Web application test automation tools, like Cypress and Playwright. To dive deeper, we have a detailed comparison of Cypress and Playwright on our blog.
• Code analysis tools, like SonarQuibe or ESLint, provide feedback on the quality of code, its maintainability, and its adherence to coding standards.
• Test environment management tools, like AWS and Azure DevTest Labs, help manage and provision testing environments.

Of course, to ensure success in testing, it's crucial to analyze requirements, examine the available alternatives, and choose tools and technologies that support the shift-left testing method and the overall testing goals.

Importance of automated testing

Many of the tools mentioned above facilitate automated testing. Automation is vital in enabling and improving shift-left testing techniques. With test automation, you can accelerate the software development process and improve the overall software quality.

The benefits of automated testing include:

• Improved test coverage: run many test cases, which results in thorough test coverage. You can run automated tests on different platforms, browsers, or configurations.
• Faster test execution: reduce the time required for testing compared to manual testing. This translates to rapid iteration and a fast-paced development cycle.
• Resource optimization: free up testers’ time to run more complex testing activities.

Automation is essential for organizations to accelerate their testing efforts, achieve superior software quality, and confidently launch high-value software products to the market.

Challenges to shift-left testing

There are two aspects of why shift-left testing can be a challenge to introduce in a company.

First, there are people. There has to be a well-thought-out cultural shift within an organization. It involves changing the mindset of the company leaders and developers and testers. Shift-left testing brings about a lot of changes, including acquiring new skills, learning new tools, and becoming more collaborative during projects. However, with the right attitude, all that preparation and implementation will pay dividends in no time.

On the other side of the equation is technology. Just like changing the mindset, preparing all the systems necessary for shift-left testing can be time-consuming and expensive. We’re referring to managing complex test environments, automation, and CI/CD infrastructures. Also, extra organization and coordination may be necessary to maintain consistent testing procedures.

Should you require any assistance in implementing shift-left testing in your project or company or help from experienced testers and QA engineers, don’t hesitate to contact us.