A Guide to Shift Left Testing & How to Implement It

Testlio

November 1st, 2024

Iterating faster creates a market advantage because it means you can adjust quickly to evolving market conditions, changing end-user sentiment, and an unforeseeable black swan (like a global pandemic). 

However, increased software delivery speed cannot come at the expense of a high-quality end-user experience. Shift Left Testing is a strategic approach that integrates testing early in the software development lifecycle to improve both the speed and quality of software releases. This approach is dubbed “shift left” because it emphasizes moving the testing phase to the left (earlier) in the development timeline.

This article will cover key aspects of shift left testing, its benefits like quicker bug detection and cost efficiency, and the challenges it may pose. It will also provide strategic steps for implementing shift left testing effectively, compare it with shift right testing and offer practical tips for adopting this methodology easily.

What Is Shift Left Testing?

Shift-left testing means incorporating testing earlier and more often in the development cycle. In software testing, shift-left often implies that developers are taking on more testing responsibilities than QA teams, but the strategy actually encourages collaboration over siloed duties in the software development lifecycle, involving the testing team earlier in the process.

There are two best-practice process changes to implement shift left: increase unit testing by your developers to raise the bar on code quality and activate your QA team earlier in the development cycle.

Benefits of Shift Left Testing

Shift-left testing brings you the benefits of continuous testing, cost savings, and greater overall quality. A shift-left approach delivers these advantages by helping you catch bugs early, avoid expensive late fixes, and reduce technical debt. Let’s explore the benefits of shift left testing further.

Continuous Testing

Continuous testing runs automated tests on apps throughout the development lifecycle, shortening feedback delays about potential risks. When automated scripts detect issues, human teams receive a notification to initiate intervention. 

Applied to DevOps, continuous testing provides early alerts to potential problems. Errors are addressed before they impact the next stage of development, minimizing bugs prior to deployment. This saves development teams time while improving software quality and reducing time to market.

Cost Savings

Using continuous testing to catch bugs early can yield huge cost savings. Consider the cost of bug fixing to quantify this benefit.

A report published by the Consortium for IT Software Quality found that poor software quality in the U.S. cost at least $2.41 trillion in 2022. This is a logical consequence of using the typical software development model, where testing occurs at the end of the cycle right before release.

The study estimates that the technical debt, just the cost to repair broken code, has grown to approximately $1.52 trillion. Developers spend about 33% of their time addressing technical debt, which significantly impacts productivity and innovation.

Shift left testing can significantly reduce costs by testing and fixing earlier in the development process. It also reduces the number of bugs and errors in the initial work by aligning coding with early test cases. 

Code is constantly analyzed, and defects are fixed as they’re discovered. There are fewer defects to fix after the final testing cycle, which ultimately costs less for the company (nearly 100 times less, according to some surveys).

It’s much easier to fix in code when developers are still writing code. If developers are knee-deep in writing while performing unit tests, teams are already poised to make minor fixes without having to go back into the writing stage.

If the software fails in customer-facing environments, the cost savings will be compounded by the immeasurable cost of brand damage and customer retention loss. 

The actual cost of brand failure via software failure is hard to estimate, but it’s safe to estimate millions of dollars more in lost revenue, renewals, and conversions. It’s no exaggeration to conclude that for some brands, a shift-left testing approach can avoid billions of dollars in losses.

Greater Overall Quality

Shift-left testing improves the overall quality of software releases by improving the observability of bugs, reducing incidents in later phases of the development process, and minimizing technical debt. 

This allows development teams to increase production speed without sacrificing software quality.

Challenges with Shift Left Testing

Shift Left Testing presents several challenges that can significantly impact developers and the development process.

• Increased Cognitive Load: Shift-left testing requires developers to balance both coding and testing tasks. This dual focus can be overwhelming, especially if developers lack strong testing skills, leading to inefficient testing practices.
• Resistance to Change: Teams used to traditional testing roles and dynamics may resist shift-left testing. This resistance often comes from discomfort with the increased interdependency and collaboration required. A shift-left testing strategy involves a significant change in team dynamics and processes, including an emphasis on test-driven development (TDD) and closer integration between developers, product owners, and QA.
• Ineffective Feedback: Shift-left testing relies on early and effective feedback to catch issues before they progress in the development pipeline. However, feedback that is unclear, irrelevant, or non-actionable can frustrate developers and slow down the development process, leading to delays and inefficiencies.

Overcoming the Challenges of Shift Left Testing

To effectively implement Shift Left Testing despite these challenges, several strategies can be adopted:

Selective Shift-Left: In complex projects, apply shift-left strategies selectively while maintaining traditional approaches for other aspects. This balances quality management without overwhelming the development process.

Prioritizing Developer Experience (DevEx): Improve developer experience by aligning testing with daily workflows, automating routine tasks, and providing customizable environments. For example, integrate preferred IDEs with testing frameworks that automatically execute tests upon code commits.

Outsourcing or Crowdsourcing Testing: For tight deadlines or limited resources, outsource or crowdsource testing tasks. This allows internal teams to focus on core tasks while external testers handle early-phase testing, ensuring compliance with project protocols.

Designing Tools and Processes: Easily integrate new tools and processes into workflows with detailed plans outlining timelines, resources, and contingencies. This improves test automation throughout the development pipeline.

Providing Clear, Actionable Feedback: Implement systems that deliver clear, actionable, and timely feedback. Tools like continuous integration servers provide immediate feedback on testing results, helping developers address issues promptly.

What Is the Difference Between Shift Left and Shift Right Testing?

Shift-left approach focuses on incremental testing during the pre-production phase of the development cycle. In contrast, a shift-right testing strategy focuses on tests after software has gone into production. 

Unlike shift-left, shift-right testing deploys methods such as A/B testing of user response, synthetic monitoring of potential user interactions, and chaos engineering of stress scenarios.

When to Use Shift Left or Shift Right

Both types of testing have their place in modern application development. Shift-left testing increases efficiency in catching bugs early, cutting costs, and speeding up product releases without sacrificing quality. 

Shift-right testing helps you catch bugs your automated tests missed, analyze actual user behavior, improve performance under stress conditions, and close security vulnerabilities. You need both shift-left and shift-right testing for complete quality assurance.

Blending Shift Left with Shift Right Testing

Integrating shift left and shift right testing strategies can improve the overall quality and reliability of software. 

Here are some practical steps to achieve this integration:

Unified Testing Frameworks

Use testing frameworks that support both early-stage and production-stage testing. This promotes consistency and reduces the learning curve for developers and testers.

Continuous Feedback Loops

Establish continuous feedback loops between development and production environments. Insights gained from production can inform early testing, and vice versa, creating a cycle of continuous improvement.

Collaborative Culture

Develop a collaborative culture where development, QA, and operations teams work closely together. Regular cross-functional meetings can help align goals and share insights from both shift left and shift right practices.

Automated Testing Pipelines

Implement automated testing pipelines that integrate both shift left and shift right tests. This can include unit tests, integration tests, and performance monitoring, providing comprehensive coverage throughout the software lifecycle.

Real-Time Monitoring and Alerts

Use real-time monitoring tools to track the performance and health of applications in production. Set up alerts for any anomalies or issues, allowing teams to respond quickly and feed this information back into the development cycle.

Incremental Rollouts

Practice incremental rollouts of new features using techniques like canary releases. This allows for testing in a real-world environment with minimal risk, and feedback from these rollouts can be used to refine early-stage tests.

Documentation and Knowledge Sharing

Maintain thorough documentation of testing practices and findings from both shift left and shift right activities. Promote knowledge-sharing sessions to share best practices and lessons learned across teams.

Therefore, team members can deliver high-quality software that meets user needs and performs reliably in production by integrating shift left and shift right testing.

Types of Shift-Left Testing

Shift-left testing can be approached in various ways, distinguished by how early in the software life cycle testing gets introduced and how long testing feedback loops are delayed. 

As new approaches to shift-left testing have emerged, testing has been pushed back further and further in the development life cycle, and testing feedback cycles have grown shorter and shorter. 

Traditional shift-left testing introduces testing later and takes longer to deliver testing feedback than newer approaches. Incremental shift-left testing waits a medium length of time to close testing feedback loops, while an Agile/DevOps approach waits a short time, and a model-based approach introduces testing almost immediately to minimize feedback loops.

Traditional Shift-Left Testing

Traditional shift-left testing moves testing back from the operational, acceptance, and system-level testing phases of the testing process by focusing on system and subsystem integration testing and unit testing. 

For example, traditional shift-left testing takes a step back from user interface testing to focus on the subsystems and units behind user interfaces. This introduces testing earlier than shift-right approaches, catching bugs earlier, and speeding up development. However, it has limitations for testing system-level, acceptance-level, and operational-level bugs, underscoring the need for shift-right testing. 

It also can have limitations when testing larger, more complex systems, which has prompted the need for other types of shift-left testing.

Incremental Shift-Left Testing

Incremental shift-left testing tackles the challenge of large software applications with complex development needs by breaking development and testing cycles into smaller components. 

These smaller segments replicate the full testing cycle at each level of testing. In other words, unit testing undergoes a testing phase before the results are passed on for subsystem integration testing, and so on through system integration testing, acceptance testing, and operational testing.

Thus, the key features of incremental shift-left testing are shorter testing cycles on smaller phases of software systems. 

This benefits development teams by preventing undiscovered bugs from being passed on into later phases of development, avoiding delays in production timelines and reducing cost overruns.

Agile/DevOps Shift-Left Testing

The Agile/DevOps shift-left testing approach takes iterative and incremental development to the next level by breaking the testing process into many short bursts of testing activity, known as sprints. Each sprint focuses on debugging a specific feature, and sprints are conducted by developers rather than testers. 

Continuous feedback test automation tools assist the process. Frequent, early testing promotes communication and collaboration between development team members and encourages the preemptive interception of bugs.

Model-Based Shift-Left Testing

Model-based shift-left testing takes an even more proactive approach to catching bugs by introducing testing at the beginning of the software development life cycle, prior to the completion of coding. Simulation testing tools apply testing to executable models while the software is still in the abstract stage of development. 

By testing executable requirements, architecture, and design models, development teams can catch bugs as early as possible, promoting error elimination from the outset. Model-based shift-left testing is growing in popularity, and refinements of this methodology will continue to advance.

How To Implement Shift Left Testing

QA has evolved from a distinct testing role to one that ensures quality throughout the whole development lifecycle.  

Testing and QA are about more than just getting to launch — they are about optimizing development for the market.

Implementing shift left testing can do that by testing earlier in the software development life cycle (SDLC) and creating a more collaborative approach to development.

1. Before the Project Starts

Product managers should bring QA teams into pre-planning meetings to start defining testable use cases that can be used alongside development activities. Getting involved this early helps QA determine an automated testing strategy for later phases of the SDLC, including API and component testing, automated GUI tests, and unit testing. 

Advanced planning also reduces manual testing needed later, ensuring it’s only used on elements that truly require it.

Early involvement helps QA set the base testing strategy early, so fewer tweaks and changes need to be made later in the final testing stages. It’ll also reduce developer time spent on debugging and decrease test failure rates.

2. During Development Planning

As development teams plan their activities and sprints, testers can identify functional and non-functional testing requirements. These tests can be done either during development sprints or as part of other automated testing packages later.

Example shift-left approaches at this stage include:

• Business-Driven Development (BDD): QA works with product owners to develop test cases that ensure all features are included in planned testing.
• Automated Testing: Testers can develop new test scripts to validate new features or capabilities and include them in build or deploy activities. Because they’re automated, developers can run them instead of having QA engineers run regression tests at the end of a release process.
• Release Testing: Before shifting to production, devs can leverage automated testing to capture more bugs before release.

3. During Dev Sprints and Work Cycles

QA teams can help break down development tasks into test suites and user stories to help developers focus on the product’s or sprint’s core functionality. Also called test-driven development (TDD), this approach ensures all code passes testing before being promoted forward and reduces compounding errors and bugs that take longer to fix later.

Testers match the test cases to the project and business requirements and developers code based on the tests. The code is tested when it’s ready, either through automated or manual testing, until it passes. Only then do developers move on to the next phase of work.

Adding a shift left testing approach to your QA strategy can benefit more than your testing team. In agile and CI/CD processes, shift-left can be a valuable resource for streamlining the development process and increasing product quality. 

A shift-left approach helps everyone focus on prevention and optimizing the life cycle from the start of every software project. A stable software application is better for your business than always patching code.

If you can shift left, you might be wondering if there’s a shift right strategy. Shifting right is the notion of testing after release and during operations to maintain quality. While many companies embrace shift left as a priority, teams can embrace both, shifting right while shifting left to remain agile.

Best Practices for Shift-Left Testing

Effective shift-left testing depends on adherence to best practices. Key best practices for shift-left testing include continuous feedback, early and frequent testing, and static code analysis.

Ensure Continuous Feedback

Continuous feedback consists of the constant flow of information about testing results and coding improvements throughout the testing process, including its shift-left and shift-right phases. 

This ongoing feedback loop forms a critical component of software testing by providing the information needed to move continuous improvement forward through the development process.

Continuous feedback includes Continuous Integration (CI) and Continuous Delivery (CD) phases. In the CI phase, small code changes immediately get shared with the team’s code repository, promoting more rapid testing cycles. 

In the CD phase, DevOps teams execute automated steps to put code into production. Together, the CI/CD phases support continuous feedback and promote continuous code improvement.

Test Early and Often

The yielding of traditional shift-left testing to newer types, such as incremental and agile methodology, underscores the importance of early, frequent testing. 

Testing early in the software development life cycle can help guarantee the quality of software while helping teams save time and money.

Use Static Code Analysis

Static analysis uses automated tools to debug source code without executing it, unlike dynamic analysis, which is performed on executed codes. 

Running code static analysis tests can help find software defects in the early phases of the software life cycle, maximizing labor and cost savings.

The Future of DevOps and Shift-Left Testing

The trend of shift-left testing toward earlier and more frequent testing has set the stage for the future of DevOps testing. 

Today, shift-left testing represents the new normal for conducting efficient software development tests. 

Time will tell how advancements like AI will interact to shape the industry’s future, but at present, shift-left testing forms a pillar of an effective QA strategy.

At Testlio, we specialize in providing world-class QA software testing across web, mobile, and enterprise applications to help you build better software faster. To learn more, schedule a call with one of our experts!