Shift-Left Testing: Testing Early and Often for Better Software

Agile practices, being adopted almost universally, necessitate faster and earlier testing in the software development lifecycle (SDLC). Bringing development and testing together early is commonly called ‘shifting left’.

In the fast-paced world of software development, quality is paramount. However traditional testing methods often leave bugs lurking until later stages, leading to costly fixes and delays. Enter Shift-Left Testing, a proactive approach that emphasizes testing earlier and more frequently throughout the development lifecycle.

Traditional testing

A typical waterfall software development project would have seen testing occur immediately before release into production. This meant that when bugs or usability issues were inevitably found, the release would be delayed until these were fixed.

In this model, testing became a bottleneck that seriously impeded the ability of projects to deliver on time.

What’s the shift left testing?

The easiest way to explain shift-left software testing is to think of the development cycle as a line running from left to right.

In the old model, testing only came into play on the far right of the line. Recognizing the bottleneck here, we now want to move the initiation of testing as far to the left as possible.

Shift Left is a practice intended to find and prevent defects early in the software delivery. The idea is to improve quality by moving tasks to the left as early in the lifecycle. Shift Left testing means testing earlier in the software development process.

Why Shift Left?

In the traditional software development model, requirements are kept on the left side of the plan, and the delivery and testing requirements on the right. The problem is that these practices can’t handle changing expectations and requirements, resulting in negative outcomes for the business such as:

• Increased costs
• Increased time to market
• Unexpected errors

Cost alone is a very strong incentive for shifting your testing to the left. Estimates indicate that over half of all software defects could be identified during the requirements phase, with less than 10% emerging during the development phase of the lifecycle. The cost of resolving these defects works in reverse:

A defect that is removed after the product has gone into the product will cost around 100 times more than one that is identified and removed during the requirements phase.

Research from the Ponemon Institute, in 2017, found that if vulnerabilities get detected in the early development process, they may cost around $80 on average. However, the same vulnerabilities may cost around $7,600 to fix if detected after they have moved into production.

The Shift Left approach emphasizes the need for developers to concentrate on quality from the earliest stage of a software build, rather than waiting for errors and bugs to be found late in the SDLC. Shifting left enables product teams to perform daily tasks like:

• Testing
• Providing feedback
• Reviewing changes and progress

Is Shift Left always appropriate?

A Shift Left testing approach may not always be able to deliver optimal performance and functioning in a real-world environment. In such situations, a Shift Right testing strategy may help to:

• Enhance customer experience
• Provide scope for implementation of test automation
• Ensure better test coverage

Shift Right initiates testing from the right, i.e., post-production. In this Shift Right practice, you’ll test a completely built and functioning application to ensure performance and usability traits. Reviews and feedback from targeted users further help in enhancing the quality of the software.

An important characteristic of the Shift Right approach is a willingness to:

• Validate a hypothesis by trying out new solutions
• Collaborate with customers to determine what is working (instead of working from assumptions)

Continuous feedback from users may help in responding better to software failures.

How to move to Shift Left

Some key strategies will help you shift left with your software testing:

Demand planning

Test analysts will engage with business and operational stakeholders, providing a forward view of demand. Having this view enables you to—ahead of time—plan and finalize:

• The budget
• Resourcing
• Test strategies

Demand planning is an integral part of the shift left approach and provides a starting point for all other activities in the test lifecycle.

Static testing

Static testing is carried out in the early cycles of the project and includes validation of requirements and design. The purpose of static testing is to find defects early in the life cycle that could prove to be very expensive to remove in the later phases of the project.

Use appropriate checklists to verify and validate requirements and design. Log defects into a defect management tool.

Unified test strategy

This is an overall, high-level strategy for testing end-to-end—from unit testing through user acceptance testing (UAT), operational readiness testing (ORT), and post-deployment testing. The strategy will cover all phases of quality control, defining clear responsibilities.

A unified test strategy allows you to analyse dependencies on environments, stubs, automation, and test data—ensuring that the respective teams can fulfil the needs.

Risk-based analysis

Risk-based analysis is carried out to determine the impact and likelihood of failure for each test scenario. This approach is used for functional, non-functional and regression types of testing.

Once the test cases are established, decide the priority for the test cases based on the finished analysis. Discuss the impact of failure with the business analyst or designer. Determine the likelihood of failure from the development team.

Benefits of a shift left approach

Several benefits can be obtained by adopting a shift left strategy. Here are some of the most important:

Automation

Shifting left gives a greater ability to automate testing. Test automation provides some critical benefits:

• Much fewer human errors
• Increased test coverage (multiple tests can be conducted at the same time)
• The ability for testers to focus on more interesting and fulfilling tasks
• Fewer production issues

Increased delivery speed

Earlier means faster. When you find defects earlier in the production cycle, you can also fix them a lot faster. As a result:

• The time between releases can be reduced significantly.
• The quality of software improves.

Increased satisfaction

Faster delivery of software with fewer defects is a major benefit of the shift-left approach.

If nothing else convinces you that this is a good move, then the smiles on the faces of your business partners should be all you need.

Recap/Key Notes:

Shift-Left helps:

• Reduce costs: Fixing bugs early is significantly cheaper than fixing them later in the process.
• Improve quality: Early testing uncovers and addresses issues before they snowball into major problems.
• Increase speed: Faster feedback loops enable quicker iteration and development cycles.
• Boost collaboration: Closer collaboration between developers and testers fosters a culture of shared responsibility for quality.

How does Shift-Left work?

Here are some key practices:

• Unit testing: Developers write unit tests to ensure individual code components function as intended.
• Integration testing: Tests verify how different modules interact and function together.
• API testing: Ensures Application Programming Interfaces (APIs) are working correctly and securely.
• Performance testing: Evaluate the software's performance under various load conditions.
• Security testing: Identifies and addresses vulnerabilities early on.

Benefits extend beyond development:

• Improved user experience: Early testing helps ensure a smooth and bug-free user experience.
• Enhanced customer satisfaction: Delivering high-quality software leads to happier customers.
• Competitive advantage: Faster time-to-market and better quality give you a leg up in the competition.

Shift-Left isn't a one-size-fits-all approach. The specific techniques and tools used will vary depending on your project, team, and organizational culture. However, the core principles of testing early and often remain constant.

Ready to embrace Shift-Left?

Here are some tips:

• Start small: Begin with a single project or feature and gradually expand your use of Shift-Left practices.
• Invest in training: Ensure your team has the skills and knowledge to effectively implement Shift-Left.
• Choose the right tools: Select tools that support your specific testing needs and workflows.
• Communicate effectively: Foster collaboration and transparency between developers, testers, and other stakeholders.

By adopting a Shift-Left mindset, you can unlock the benefits of early and frequent testing, ultimately delivering higher-quality software, faster, and at a lower cost. Remember, testing early is not just good practice, it's smart business.