Shift Left Testing: A Secret Mantra for Software Success

The new Shift-Left Testing, a DevOps mantra in Software Development:

A quick recap of all the video tutorials in DevOps was explained in our earlier tutorial. Now, we will see about Shift left testing.

When I use the term ‘Shift Left’, you might be wondering what am I referring to as Shift Left in the software??

2+ decades ago, when I started my career as a software tester there was no separate ‘Testing Phase’ for Software development and Testers Role never used to exist at all. Developers used to develop the software, test themselves and make a software release.

Further Reading => Informative DevOps Tutorial Series

The concept of Software Testing got introduced gradually when defects from the production started hitting the budget of the project and hence ‘Functional Testing’ came into effect with a very lean team of Testers. At that point in time, we were just two Testers against a team of 20 Developers.

Shift Left Testing Approach

The IT Industry started following the waterfall model for software development wherein, as we all know, the software development lifecycle goes sequentially in the order of Requirements => Design => Coding => Testing.

So, if you start from the left to right, the Testing Phase is to the extreme right of the software development lifecycle.

Introduction to the Concept of Shift Left

Over a period of time, people realized the importance of Software Testing and the impact of keeping the ‘Testing Phase’ on the extreme right or at the end of the Software Development Lifecycle. This realization happened because the cost of the bug identified towards the extreme right and at the end was very high and enormous effort & too much time was required to fix them.

There were cases where after spending so much time and effort on software, due to the crucial bug identified at the end, the mission-critical software could not be released to the market thereby resulting in a huge loss.

Hence, because of the identification of the bug during the last stage either the release was delayed or at times, the software was scrapped by considering the effort required to fix them, which was really not worth it.

Software Development Phase

‘Defects are less costly when caught early.

This realization and the big lesson learned, introduced a great revolution in the software industry and gave birth to a new concept called ‘Shift Left’, which means shifting the ‘Testing Phase’ to the Left from Right or involving Testing at every stage and involving testers throughout.

Shift Left testing also means that just don’t test in the end but test continuously.

SDLC Phases

Shift Left approach

What is Shift Left Testing?

Firstly, the principle of ‘Shift left’ supports the Testing team to collaborate with all the stakeholders early in the software development phase. Hence they can clearly understand the requirements and design the test cases to help the software ‘Fail Fast’ and enable the team to fix all the failures at the earliest.

Shift Left approach is nothing but involving the testers much earlier in the software development life cycle, which in turn would allow them to understand the requirements, software design, architecture, coding, and its functionality, ask tough questions to customers, business analysts, and developers, seek clarifications and provide feedback wherever possible to support the team.

This involvement and understanding will lead the testers to gain complete knowledge about the product, think through various scenarios, and design real-time scenarios based on the software behavior which would help the team in identifying the defects even before coding is done.

How Does Shift Left Influence Software Development?

Shift Lift Approach influences Software Development in several ways.

Given below are a few key points about Shift Left:

  • The Shift Left approach focuses on involving testers in all and most importantly the critical stages of the program. This enables the testers to divert their focus from defect detection to defect prevention and to drive the business goals of the program.
  • The shift Left approach provides, high importance to Testing with which the roles and responsibilities of the testers increase immensely.
  • With the responsibility being increased for the Testing team, the team just does not focus on ‘Testing the software to identify the bugs’, but proactively works with the team right from the initial stages to plan and build a robust and effective testing strategy by providing a great Test leadership and guidance to the team by focusing on the long-term vision of the product, rather than just taking the responsibility of the testing work.
  • The Shift Left approach gives the opportunity for the Testers to design the tests first, where the tests are completely focused on the customer experience and their expectations which in turn will enable the developers to develop the software based on these tests and hence meet the customer needs.
  • The Shift Left approach just does not end with the Testers alone. Moving to the let and carrying out the testing activities continuously will also allow the Developers to take more ownership of their code and increase their responsibilities on testing.
  • The shift Left approach also encourages Testers to adopt Behavioral driven development BDD and Test-driven development TDD, which helps in preventing the defect’s induction into the software.
  • Shift Left Testing in Agile: Shift Left approach supports forming Agile Scrum Teams which mandatorily includes Testers along with the other roles and includes Testers in regular stand up calls, other interactions, review meetings which have made the testers have more information related to the program and hence has allowed them to indulge and involve in the detailed analysis of the software and provide rapid feedback which would help in preventing the defects grounded in the software.

Overall Shift Left testing calls for the testers to ‘Get Involved Early’, as early as possible and engage in the discussion and collaborate on ideas, requirements at every stage where the outcome of the stage has a bearing on the value of the final deliverable and also help the project to identify the risks and mitigate it in advance.

Shift Left

What should Testers Do Differently in Shift Left?

Given below are a few key factors to be noted as what the Testers do differently in Shift Left Strategy:

#1) Test team needs to engage early in the system right from project initiation so as to develop the integration with the rest of the team and the business to provide useful inputs at every stage of the software development.

#2) Test team should work with the Business & Operations team and gain clarity on the program and provide a clear view of demand and help in planning efficiently on resource ramp-up needs, training needs, and testing tool requirements to the program well in advance.

#3) Test teams must interact with all the business stakeholders early in the software development to get clear visibility of the product & design a unified testing strategy and plan for an optimized testing effort, analyze dependency on test environments, third parties, stubs, etc, and prepare a robust automation strategy and framework and build an effective test data management plan.

#4) Test team has to work with the rest of the team in providing great Test Leadership and guidance to the team thereby keeping the long-term product vision in mind rather than just taking the responsibility for testing activities.

#5) Requirements are the key and basis to the success of any program and well-defined requirements define the success of the project. During the Requirements Planning phase, Testers need to review and analyze the requirements for any ambiguity, better clarity, completeness, testability, acceptance criteria definition, etc.

Also need to identify the missing requirements (if any), and understand the dependencies and implementation strategies.  Clear Requirements helps the software to ‘Fail Fast’ and fix all the failures at the earliest.

#6) Bring enough clarity and precision to requirements by bringing out the real examples that illustrate the features that are in use.

#7) Testers need to attend Design review meetings regularly and understand the product design and architecture and identify the design flaws, suggest alternate design options, identify the loopholes, and create test scenarios accordingly to break the designs.

#8) Testers need to carry out Static Testing (reviews) well in advance and provide feedback on key project documents so that defects are prevented from getting grounded into the software and widening its effect later.

#9) Test team should collaborate with the design and development team in providing test scenarios in advance to develop the code and address all possible real-time scenarios and business flows.

#10) Test team has to design strong and robust test scenarios so that only a few defects are identified during testing and major defects are prevented while entering into the testing phase.

#11) Testers have to Test as early as possible, be it on a standalone or local system, so that defect does not get into later stages.

The whole crux of the ‘Shift Left’ concept for Testers is to find the Defects as early as possible by all possible means.

Finding Defects using Shift Left

Benefits of Shift Left Testing

The Shift Left approach works based on the agile manifesto and has several advantages too.

They are:

  • Individuals and interactions over processes and tools.
  • Working software over comprehensive documentation.
  • Customer collaboration over contract negotiation.
  • Responding to change over following a plan.

We can see that while the value is there in the items on the right, we value more for the items on the left side.

Well, Shift Left is about bringing the idea of testing earlier in the process thereby resulting in better and more efficient testing and improving the quality of the software.

In a nutshell, the Shift Left Testing process is:

  • Finding the defects early thereby reducing the cost of the project.
  • Testing continuously again and again to reduce defects in the end.
  • To automate everything and improve time to market.
  • To focus on customer requirements and improve the customer experience.

Shift Left Focus


The ‘Shift Left’ concept brought a huge transformation for the entire ‘Testing’ role. Until then, the sole focus for the Testing was only on ‘Defect Detection’, and now the aim of the ‘Shift Left’ from the Testing perspective is a journey of ‘Early Defect Detection to Static Testing.

Thus, Shift Left is a Big Leap in the software industry in Software Development methodology toward speed to market, improving software quality, and reducing ‘Time to Market’.

About the Author: This article is written by STH team member Gayathri Subrahmanyam. She is in software testing since the ’90s, just when the tester role was introduced in the industry. During her testing career, she has done a lot of TMMI assessments, Test Industrialization works, and TCOE setups in addition to handling test deliveries and implementing DevOps practices for a huge engagement. But according to her, learning never stops…

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61 thoughts on “Shift Left Testing: A Secret Mantra for Software Success”

  1. Hi, Thanks for sharing such a wonderful shift-left testing approach blog!! I want to share one of the best blog of shift-left testing approach in software quality. This will be giving a gist about how shift-left approach is worthy for businesses.

  2. Hi, thank you for great article! For me it is new testing strategy and i will deffinetly try it in practice. Is using automation tools necessary? Does someone have expirience without using automation testing tools?

  3. Really Thank You Gayathri Subrahmanyam, awesome article and very good presented and explained with very easy and simple words.

  4. To help clear up your misunderstanding about software testing history, please take some time to research and educate yourself about IBM’s Rational Unified Process. Here is a link to a PDF describing iterative software development that I hope you find useful:

    In my experience, 25+ years ago testing not only existed, it thrived and has been an integral part of iterative software development. Yes, that’s right, software testing as a discipline has been part of iterative software development since the mid-nineties but I can understand if you were not aware of this theory or its practice especially if your training hasn’t included this approach or the countless other knock offs of RUP that have sprung up over the years that don’t see the need for such rigor.


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