Embracing shift-left testing in software development: Moving towards proactive quality assurance

Learn how to implement various types of shift-left testing and take a proactive approach to quality assurance.

Shift-left testing is an approach to software testing that focuses on integrating testing early in the software development lifecycle (SDLC).

Traditional SDLC implies that testing is done after requirements have been analyzed and defined, and design and coding stages completed.

Shift-left testing is a proactive approach to software quality that contrasts with traditional quality control methods that often lead to inefficiencies, rework, and dissatisfaction in teams. Drawing from the principles of Total Quality Management (TQM), shift-left testing emphasizes quality assurance over mere quality control (QC).

6 arrows pointing to the right, labeled in order: Planning and requirements testing, Defining requirements, Design, Coding, Testing, Deployment

The shortcomings of post-development testing

Post-development testing, also known as shift-right testing, essentially checks whether the software meets the specified requirements and expectations — emphasizing quality control (QC) over quality assurance (QA). However, this approach can be problematic when used exclusively. It often leads to significant rework if the quality standards are not met, negatively impacting team morale and wasting valuable resources. Moreover, the QC process can inadvertently create a perception of diminished value in the engineer’s efforts, as their work is subject to rigorous scrutiny and potential rejection.

Consider a factory producing paper clips where QC identifies every third clip as defective. This constant inspection, while ensuring only quality products reach the customer, leads to inefficiencies. The factory operates at reduced capacity, continually discarding defective clips. This analogy mirrors the pitfalls of pushing testing to the later stages of software development.

The shift-left testing approach draws inspiration from TQM, emphasizing quality assurance over control. It proposes integrating testing in the earlier stages of and throughout the software development process. By identifying and addressing issues at the onset, the need for extensive rework is significantly reduced. This approach not only enhances efficiency but also aligns with the TQM ethos of embedding quality into every step of the production process.

The difference between Quality Assurance (QA) and Quality Control (QC) is pivotal. QA focuses on processes and practices that prevent defects, whereas QC involves detecting defects post-occurrence. Shift-left testing champions the QA approach, fostering a culture of proactive defect prevention rather than reactive detection.

Types of shift-left testing

Even though the shift-left testing is quite a simple approach to move from QC to QA, some categorize it into a few slightly different types.

Traditional shift-left testing: 

This approach involves integrating testing processes at earlier stages of the software development life cycle (SDLC). The focus is on starting testing activities as soon as possible, often in parallel with the initial stages of development. This can include early unit testing, integration testing, and involvement of QA teams from the onset of the project.

Agile/DevOps shift-left testing

 In the context of Agile or DevOps, shift-left testing is deeply integrated into the iterative development process. Continuous Integration (CI) and Continuous Deployment (CD) pipelines are typically utilized, where automated tests are run with each code commit or build.

Incremental shift-left testing

This approach involves gradually moving testing earlier in the development process in a step-by-step manner. It's a more cautious approach compared to a full-scale immediate shift. Incremental shift-left testing allows teams to slowly adapt their processes and tools to accommodate earlier testing, making it easier to manage and less disruptive, especially in organizations where a sudden, comprehensive change might be challenging.

How to get started with shift-left testing

After understanding the importance and benefits of shift-left testing, the next step is to implement this approach effectively. Here are practical steps to guide you through the testing process:

Start with requirements testing

Early testing of requirements is crucial in ensuring alignment with stakeholders' and the development team expectations. This step not only helps in efficient planning and resource allocation but also improves communication and understanding among team members, leading to a smoother software development process. By validating requirements early, development teams can save time by reducing the need for extensive rework later.

Empower developers to write automated tests

Encouraging developers to write more unit tests, as well as other types of automated tests — such as API testing or integration testing — is essential. This practice ensures that the code is tested right after it's written and before it's passed to QA teams. It minimizes time wasted in queues waiting for testers and reduces context switching if the code needs amendments. QA professionals can assist developers in covering test cases that might not be immediately obvious to the developers themselves.

Advance development with test-driven development (TDD)

Implementing TDD can significantly enhance traditional shift-left testing. In TDD, developers write tests before the actual code, ensuring that only the necessary code is written to pass the tests. This approach simplifies the code, reducing complexity and potential errors, and embeds testing even deeper into the development phase.

Implement mob programming

Mob programming takes interactive work to a new level. In this collaborative approach, queues and late feedback issues are virtually eliminated because mob programming promotes continuous feedback. Communication is significantly improved, and QA professionals become an integral part of the development process. They not only understand the solutions better but also actively influence them. This leads to even less waste and rework, optimizing the development process.

Shift-left testing represents a strategic and cultural shift in software development, focusing on quality assurance from the very beginning of the product development lifecycle. By adopting these practical steps, teams can not only improve the efficiency and quality of their software products but also foster a more collaborative and proactive work environment. Embracing shift-left testing is not just about changing a process; it's about committing to a mindset where quality is embedded in every step of software creation.

Beginning with shift-left testing paves the way for a comprehensive TQM approach. It establishes a foundation of early defect prevention and detection, essential for the broader TQM framework. 

The shift towards shift-left testing in software development signifies a move away from reactive quality measures to a more proactive, efficient, and quality-focused approach. It not only mitigates the risks associated with late-stage testing but also enhances team satisfaction and resource utilization. Embracing shift-left testing is not just a change in process; it’s a strategic, cultural shift towards better quality assurance, aligning perfectly with the principles of Total Quality Management.


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