Shift Left Testing: Principles, Approaches, and Best Practices

What Is Shift Left Testing? 

Shift left testing is a software testing approach that involves integrating testing early in the software development lifecycle. It moves testing activities towards the left in the project timeline, closer to the design and planning stages. The goal is to identify and fix issues earlier, rather than in later phases of development. This can reduce the time and costs related to bug fixes.

By shifting testing processes to the left, teams focus on quality from the outset, adopting a proactive testing strategy. It encourages developers, testers, and operations teams to collaborate closely from the early stages of development. Testing is thus an integral part of the development process rather than a final hurdle.

Why Do We Need Shift Left Testing? 

Shift left testing addresses the challenges and limitations of traditional delay-intensive testing approaches by making testing a continuous activity. It helps in detecting bugs and issues early when they are easier and less expensive to fix. It also improves the quality of the final product and reduces the likelihood of critical defects at later stages, which can derail project timelines.

Shift left testing helps encourage a DevOps culture, improving collaboration among cross-functional teams. It aligns with the agile methodology's principle of rapid, iterative development cycles, enabling faster release times and more reliable software deliveries.

Tzvika Shneider

CEO, Pynt

Tzvika Shneider is a 20-year software security industry leader with a robust background in product and software management.

Tips from the expert

• Integrate security testing into the development phase: Incorporate security testing tools into the development process to identify vulnerabilities early, reducing remediation costs.
• Encourage developer-led security assessments: Train developers to conduct initial security assessments of their code, fostering a security-first mindset from the start.
• Automate code reviews: Use static analysis tools in the CI/CD pipeline to automatically review code for security flaws before it moves further down the development lifecycle.
• Leverage unit tests for security: Include security-focused unit tests to validate proper handling of input validation, data sanitization, and error handling at the code level.
• Conduct threat modeling sessions early: Perform threat modeling during the design phase to anticipate potential vulnerabilities and design appropriate countermeasures.

Shift Left Testing Principles

Here are the main principles of shift left testing:

Early Testing Integration

The first principle is to include test planning and execution from the initial stages of the software development lifecycle. Early testing helps in understanding risk areas, setting clear quality expectations, and identifying potential issues before they become embedded in the codebase.

The benefits of early testing integration include improved insight into feature viability, enhanced security, and overall better software quality. It encourages a comprehensive understanding of the project's scope and requirements.

Related content: Read our guide to API Security

Continuous Testing

With continuous testing, tests are conducted at every stage of development. Rather than being a final phase, testing becomes an ongoing activity, enabling immediate feedback on the code's current state. This continuous loop of testing and feedback ensures that any defects are caught and addressed promptly, reducing the time and effort required for remediation.

Implementing continuous testing requires the adoption of automation tools and practices to manage the volume and frequency of tests efficiently. It aids in maintaining high-quality standards throughout development, supporting frequent and reliable releases.

Test Automation

Test automation enables rapid, repetitive testing without manual intervention. Automation tools can execute a large number of tests in parallel, providing instant feedback. They accelerate the testing process and increase its accuracy and consistency.

Automated tests help ensure thorough coverage, freeing human testers to focus on more complex testing tasks that require critical thinking. They’re also useful for building Continuous Integration/Continuous Deployment (CI/CD) pipelines.

Learn more in our detailed guide to shift left testing.

Shift Left Testing vs. Shift Left Security 

The shift left approach can be applied to testing specifically or security more broadly.

Shift left testing emphasizes testing early and often. By incorporating testing from the very beginning of a project, developers can detect and address defects before they evolve into more significant issues. This approach saves time and resources while enhancing the quality of the software, preventing bugs from being built into later versions of the software.

Shift left security focuses on integrating security practices at the start of the development process. This ensures that security considerations are not an afterthought but are embedded in the initial design and architecture decisions. The key benefit of this approach is the prevention of security vulnerabilities from the outset, reducing the risks and costs associated with addressing security issues after deployment.

While shift left testing aims to improve the quality and reliability of software, shift left security is targeted at making the software more secure from the start. Both strategies advocate for early intervention, but their primary focus distinguishes them: quality and bug prevention in shift left testing versus security and vulnerability management in shift left security.

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Shift Left Testing Approaches

There are several ways to implement a shift left testing approach.

Traditional Shift Left Testing

Traditional shift left testing involves integrating standard testing procedures much earlier in the development cycle. It emphasizes manual and automated unit tests during the initial coding phases. By moving tests to the beginning of the development lifecycle, this approach aims to uncover and fix defects before they progress into more advanced stages of development.

Key aspects of this type of testing include a strong dependency on the development team's readiness to adopt thorough unit testing, integration testing, and system testing early. It requires robust test planning and a well-defined process to ensure that quality gates are implemented at the start of the project lifecycle. 

Incremental Testing

Incremental testing in the context of a shift left approach involves breaking down the testing process into smaller, manageable segments and integrating these tests earlier in the development stages. This method supports a gradual increase in the complexity of the testing scenarios as development progresses, aligning with the iterative release of features.

In this approach, testing starts with basic unit tests and progressively incorporates more complex integration and system tests as new functionalities are developed and added to the product. Incremental testing is particularly effective in agile environments where continuous integration is a priority. It allows teams to address and resolve issues in real time.

Agile Testing

Agile testing is a dynamic and flexible approach to shift left testing that aligns closely with agile development principles. It involves continuous collaboration between developers, testers, and business stakeholders throughout the development cycle. The aim is to adapt testing practices to match the pace and requirements of agile development processes.

Agile testing includes frequent reassessment of test plans as project requirements evolve, the use of automated testing to keep up with frequent code changes, and a focus on customer feedback to guide testing priorities. 

Model-Based Testing

Model-based testing in the shift left approach utilizes high-level models that represent desired behaviors of the system to generate test cases automatically. This type of testing allows for the early validation of requirements by converting them into verifiable models and using these models to create tests that can be executed as soon as the corresponding system or component is developed.

Model-based testing provides a systematic approach to test case generation, reducing the potential for human error and increasing the coverage of the testing. This method is particularly useful in complex systems where the interactions between different components can be difficult to predict and simulate manually. It enables the identification of edge cases and non-obvious scenarios early in the development process.

Related content: Read our guide to security automation

Shift-Left Security Testing

Shift-left security testing emphasizes integrating security checks into earlier stages of software development. This proactive approach ensures that security vulnerabilities are identified and mitigated early, reducing the risks and costs associated with addressing them post-deployment. By moving security testing to the left in the development timeline, teams can embed security considerations into design and coding processes. This involves practices such as static application security testing (SAST), threat modeling, and secure code reviews, enabling developers to detect flaws early.

Another critical aspect of shift-left security testing is fostering a security-focused mindset across all teams. It requires cross-functional collaboration between developers, security engineers, and quality assurance (QA) professionals to embed security requirements into user stories and acceptance criteria. This collaboration creates an environment where security becomes an integral part of every development phase, minimizing the occurrence of vulnerabilities and improving overall software quality.

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Best Practices for Implementing Shift Left Testing 

Here are some recommended practices for adopting a shift left testing approach.

1. Foster a Culture of Collaboration

To support shift left testing, it’s important to create an environment where communication between developers, testers, and operations teams is open and encouraged. By promoting mutual understanding and cooperation, team members can work together more effectively from the start of the project.

Encourage regular meetings and discussions where team members can share insights, updates, and challenges. Use tools that facilitate collaborative work, such as shared code repositories and real-time communication platforms. Establish a blame-free culture that values learning from mistakes over punishing them.

2. Leverage Test Automation

Test automation allows teams to execute more tests in less time, providing quick feedback on the impact of recent changes or new features. Automation reduces the manual effort required for repetitive tasks, allowing testers to focus on more complex and high-value testing activities.

Select automation tools that integrate easily with your existing development and testing environments. Develop a suite of automated tests that cover critical paths and functionalities. Ensure that these tests are maintained and updated as the project evolves to keep them effective and relevant.

3. Optimize Test Data Management

Effective test data management is critical in ensuring that tests are realistic and provide accurate results. Optimizing test data involves creating, managing, and maintaining data sets that simulate real-world scenarios without violating privacy or security regulations.

Implement strategies to provide relevant and up-to-date test data at all stages of development. Use tools for test data generation and management that automate the process of creating realistic data sets. Ensure data privacy by anonymizing sensitive information and complying with relevant data protection regulations.

4. Implement Test-Driven Development (TDD) 

Test-driven development is a software development approach where tests are written before the actual code. TDD ensures that testing drives the design and development process, which is aligned with the shift left philosophy.

Start by writing a test for a new function or feature, then develop the code to pass the test. This cycle of testing first and coding second encourages simpler, clearer, and more bug-resistant code. It also ensures that testing considerations are integrated from the very beginning of the development process.

5. Establish Feedback Loops

Creating effective feedback loops is crucial for the continuous improvement of the development and testing process. Feedback loops help identify successes and areas for improvement, allowing the team to adapt and evolve their practices.

Integrate feedback mechanisms into all stages of your development pipeline, from initial design through to production. Use automated tools to gather feedback on code quality, user experience, and performance. Regularly review feedback with the team, and use it to inform future development cycles.

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Shifting API Security Left with Pynt

Pynt is an Innovative API Security testing platform exposing real API threats through simulated attacks. Shifting left API security helps companies continuously monitor, classify and attack poorly secured APIs for threats pre-production, before hackers do. 

This unique approach identifies all APIs in use, performs attacks in real-time, then provides fix automation to the exploited vulnerabilities. Using Pynt allows you to address risks that are proven to be exploitable, and thereby prioritize the real threats hackers are lurking the web to target.

Learn more about Pynt for API security testing