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Importance of Shift Left and Shift Right Testing Approaches

Gone were the days, when testing was considered as a separate phase and is carried out post-development of the software application. With the introduction of new and innovative approaches of software development or may be called software models such as agile and DevOps, testers are now able to show their presence and apply their sincere efforts towards the achievement of quality traits in a software application, right from its seeding.

Further, it is also pertinent to mention that despite continuous and strenuous testing efforts put up right from the dawn of the development phase till the production, a software application may lack in some or more qualities from user’s point of view, keeping in view the user’s expectation to operate software functionalities along with its performance in real world conditions and environment. Thus, testing both at the starting & during the development, and after the production is equally important to provide best quality software products to users.

The approaches of testing the software application starting from the initiation of its development and throughout the development, and testing done post-development are generally referred to as shift left testing approach and shift right testing approach.

Shift Left Testing Approach:

Shift left testing approach as the name suggests, shifts the testing process to the left of the development phase, i.e. testing starts at the starting point of the development. Basically, testing process begins with the development and is being carried out throughout the development phase with the vision to prevent defects rather encountering with unexpected defects at a later stage.

Shift left testing is an approach to introduce testers at an early stage of software development to ease the task of developers in developing the required software application of acceptable quality based on the specified requirements and specifications. Based on the requirements and specifications, acceptance criteria both for the software and business requirements is being defined and created. Continuous testing right from the beginning of the development phase and throughout the development helps in identifying, locating and removing or correcting the flaws occurring at each level of the development, which subsequently helps in reaching the acceptance criteria defined for the software. This approach may comprise of different types of testing for a particular job, including regression testing to test the originality after applying patches.

The early introduction of the testing process and not after the software development provides flexibility to the developers to implement dynamic changes throughout the development on the continuous perusal of feedbacks, reviews and reports provided by the testers, which is needed to apply patches or correction to remove bugs or defects as earliest as possible. This approach prevents or minimizes the presence of defects at the end of the development i.e. at the point of delivery or release.

Thus, shift left testing approach may be seen as an easy and economical way of eliminating the efforts, time and cost in correcting the software at a much complex state, when it is completely developed and is ready to release, and is almost technically & economically infeasible to implement changes in the application.

Shift Right Testing Approach:

When it is possible to develop software product of desired quality in an economical and convenient manner using shift left testing approach, then why shift right testing approach?? Well, the developed software adheres to the quality and attributes as specified in the business and software requirements, but what about the functioning and performance under real conditions and in the real world environment. Although, system is completely developed in compliance to stated requirements and specification, but how to encounter with the unexpected events or circumstances occurring with the software such as slow performance, crash down, failure and many such things.

Shift left testing approach is an essential requirement but solely not enough to certify the quality of the software as user experience and reviews is equally important to business/software requirements in determining the software quality.

Shift right testing approach initiates the testing task from the right i.e. post production of the software. The software application present at the right end, i.e. completely built and functioning software application is being tested to ensure performance and usability traits. Feedbacks and reviews are received from targeted users to experience satisfaction in using and managing the software in real world conditions, which thereby helps in improving the quality further.

Although, shift left testing provides the scope of early testing of software to prevent defects, still shift right testing approach has its own unique advantages over shift left testing like

  • Automation of a complete and stable software application is easy to be done in comparison to unstable application (partially or not completed).
  • As compare to shift left, shift right approach provides wider test coverage as testers have the access to test complete system at a much larger time.
  • As targeted users are involved in the approach, the strategy of right shift provides feedback and reviews of the end users, which helps to improve quality of the software at a much larger extent.


In view of the above stated facts, it may be concluded that both shift left and shift right testing approaches are equally important and delivers unique and different way of testing the software application, which are adequate to touch each and every aspect of the application to ensure best possible quality.

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