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Understand the concept of shift-left testing in an Agile development process and how it helps speed up testing without reducing application quality.

Agile development prioritizes short sprints so new features or changes can be deployed to customers frequently in smaller releases. The idea is to deliver changes incrementally so customers can try out new features and suggest changes. The Agile theory is that development teams prioritize all customer changes into work tasks and assign them to sprints or iterations until enough features and fixes accumulate to create a release.

Releases can be daily, weekly, biweekly or monthly. The advantage is that it gives customers more frequent releases that are smaller and more manageable. Prior to Agile, software releases were larger than life and included six months or a year, maybe two of feature changes and fixes. The result was overwhelming to customers who needed to verify every change before going live and overwhelming to systems, sometimes causing catastrophic infrastructure failures.

This guide describes the concept of shift-left testing in an Agile development process and how it helps speed testing without reducing application quality.

What Is Shift-Left Testing?

Agile testing happens during sprints, where testers verify features and fixes and then try to cram in some sort of regression testing right after an iteration ends and before starting to test the next iteration’s work. Shift-left testing takes Agile testing and moves it up front—literally alongside development.

Shift-left testing is a method of software testing where testing begins with development. Shift-left means testers start testing further to the left of the software development lifecycle (SDLC) or when design and coding begin. The idea is that the sooner testing starts, the more defects testers can identify early in the SDLC where they can be fixed and retested without delaying a scheduled release.

Shift-left testing aims to speed up testing while reducing the number of defects found at the end of the development cycle. Think of it as proactively finding defects, starting with design and testing every feature’s code as it gets created. Practicing shift-left testing requires a collaborative team that communicates. Some teams practice shift-left using TDD (test-driven development), or more frequently, testers become involved in reviewing code and creating unit, integration and short automated test scripts. The automated test scripts become the regression test as coding progresses. Testers would then execute or review unit and integration scripts in the code and then continuously create the automated test scripts throughout the development cycle.

Testing speed improves because testers aren’t trying to wedge in regression test execution between sprints or right before a release. Defects are found earlier, reducing the risk of finding critical defects before a release is deployed or right after deployment. Shift-left testing speeds up testing but maintains application quality.

Advantages and Disadvantages of Shift-Left Testing

Advantages of shift-left testing include:

  • Improved customer experience post-release
  • Builds a productive and collaborative team
  • Supports early bug detection and continuous testing
  • The earlier testing starts, the more testing gets completed
  • The more testing gets completed, the fewer defects get released to customers
  • Increased testing speed and efficiency
  • No more rushing around trying to cram in regression tests before a release

Finding defects or even missing requirements early is a good thing. The more defects that are fixed early on, the less likely teams are to acquire technical debt. Technical debt is all those defect fixes that get pushed off to fix “later.” Technical debt can be debilitating to development teams and applications. The less debt the application accumulates, the better the quality.

Shift-left testing also contributes to better team management. Keeping testing running alongside development means one team function is not lagging behind the other. Instead of testing slowing down development due to defects and issues, the two run side by side. Think of it as rather than running a relay race where development hands off the baton to testing, and then testing hands off the baton to deployment—each of these run together and reach the release together.

It sounds silly or obvious, but the more a team can work side by side on projects, the higher the quality. For example, if a developer is coding a feature and doesn’t realize that feature impacts another, they may code in a defect. Whereas if a tester is testing during code development, an experienced tester will notice that although the new feature works, the one it’s connected to does not. Think of working collaboratively as a chance to improve quality while you work and learn different skills. Testers may pick up a bit of coding while developers learn more about the application and how the parts connect.

Disadvantages of shift-left testing include:

  • Less testing that verifies customer workflows or end-to-end system testing
  • Puts more focus or pressure on the quality of user acceptance testing
  • Test automation can be problematic for some applications, so there may be ongoing rework on automated regression tests
  • Can be time-consuming to review failed tests continuously

Development and testing teams need to weigh the pros and cons of shift-left testing to be sure it fits. There may be ways to change testing so that end-to-end tests are created. To reduce automated test maintenance and failure analysis, try using an automated testing tool that features self-healing AI technology.

Best Practices for Using Shift-Left Testing

Best practices for using shift-left testing in Agile development:

  • Testing activities begin when design and development begin
  • Create a team that’s collaborative and communicative with shared goals
  • Invest in test automation tools that help developers and testers create unit, integration and automated regression testing scripts
  • Consider adding TDD to development work for initial unit and integration testing but train testers how to execute and review results
  • Create test environments that testers can quickly spin up and resemble production
  • Plan ahead for creating test data and ways to keep data refreshed easily
  • Practice continuous improvement and continuous learning

Keep in mind that development teams cannot simply flip a switch and shift left on the fly. Create a strategic plan to gradually move to a shift-left approach so testers and developers can get on the same page and have time to learn. Work habits die hard, so be prepared to be patient. It may take time for testers and developers to learn to work alongside each other.

Provide training and tools that integrate together and are useful. Never buy tools that create additional work or expect teams to use multiple tools for the same purpose. When moving to shift left, teams need lean processes with little or no wasted effort or duplicate effort.

Be prepared for a learning curve for test automation. A good approach is to have a developer or two help support the QA team for a few months until they get up to speed. Encourage testers to share their knowledge of the whole application with developers. The more developers understand how different functions work in the application, the higher the code quality.

Can Shift-Left Testing Speed Up Testing Without Making Quality Worse?

Yes, shift-left testing can improve testing efficiency and speed without negatively impacting release quality. Testing teams can test faster and still be effective. With shift-left testing, testing becomes more flexible and adaptable. Shift-left testing is creative. Testers and developers may do exploratory testing or practice parallel testing to help cover more browsers and platforms simultaneously.

Teams can test efficiently without sacrificing quality. Testers work alongside development rather than waiting for completed code to start testing when using shift-left testing. QA testers can work with developers to create test processes that save time and extend test coverage. Agile development teams can deliver high-quality application releases when testing is planned, lean and effective.


About the Author

Amy Reichert

A QA test professional with 23+ years of QA testing experience within a variety of software development teams, Amy Reichert has extensive experience in QA process development & planning, team leadership/management, and QA project management.  She has worked on multiple types of software development methodologies including waterfall, agile, scrum, kanban and customized combinations. Amy enjoys continuing to improve her software testing craft by researching and writing on a variety of related topics. In her spare time, she enjoys gardening, cat management and the outdoors.

 

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