Shift Left Testing for Humans: A Practical Guide


Rahul / August 04, 2023

12 min read––– views

Have you ever spent days debugging an application only to find a tiny issue that would’ve taken minutes to fix if caught earlier? As coders, we’ve all been there.

Shift-left testing is a technique focused on finding bugs as early as possible in the development process. By moving testing activities “left” - earlier in the lifecycle - we can detect issues when they’re easiest and least expensive to fix.

In this guide, I’ll show you what shift-left testing means in practice and how you can implement it for your team. You’ll see how a little extra effort upfront saves a ton of headaches down the road.

What Is Shift Left Testing?

I'm always looking for ways to improve our process and catch bugs earlier in the projects I build. One approach that has really helped is shift left testing.

Shift-left testing means starting your testing activities earlier in the development lifecycle. Basically, you move testing left on the timeline. Instead of waiting until the end of a sprint to test, you start testing individual components as developers complete them.

Why Shift Left? The Benefits of Early Bug Detection

As a Coder, I'm always looking for ways to improve the testing process and catch bugs as early as possible. That's why I'm such a big fan of Shift Left testing.

So why else shift left? Here are a few key reasons:

  • Improved quality. Finding issues earlier leads to higher-quality end products with fewer defects.

  • Reduced risk. Catching bugs sooner mitigates the risk of major issues causing delays further down the line.

  • Better collaboration. Early testing promotes more collaboration between testers and developers. We can provide feedback right away, so problems get addressed faster.

  • Faster feedback. Shifting left means testing happens concurrently with development, so issues are detected and reported quickly. Developers get test results in real-time.

  • Less rework. Fewer bugs making it into later testing phases means less time spent fixing and re-testing the same things.

As you can see, shifting testing left offers some serious benefits. While it may require more upfront planning, the long-term rewards of quality, risk reduction, and efficiency make it worth the effort.

In my experience, integrating testing right from the start results in a better end product and a smoother development process overall.

Who wouldn't want that?

Shift Left in Action: An Example We Can All Relate To

For me, the best way to understand shift left is through an example we can all relate to - cooking a meal!

When I first started learning to cook, I would follow a recipe step-by-step, only tasting the food at the very end. More often than not, I’d realize I added too much salt or spice and would have to start all over.

Over time, I learned the value of “shifting left” and tasting as I cooked. Maybe the sauce needed more garlic, or the rice was bland. By identifying issues early, I could make adjustments and avoid ruining the whole dish. The end result? A tasty meal that I felt confident serving to friends and family.

The same principles apply to software testing. When we shift testing left, we identify bugs and problems earlier. Instead of waiting until the final testing stages, we build in frequent reviews, demos, and testing throughout the development cycle. We taste the “sauce” to check that features are implemented correctly. We try the “rice” to ensure the UI and experience meet expectations. By shifting left, we reduce wasted effort, decrease costs, and deliver a higher-quality end product.

Of course, there are challenges to shift left testing. It requires collaboration between teams and an agile mindset focused on incremental improvement over perfection. But the benefits to moral, productivity, and customer satisfaction make overcoming these obstacles worthwhile.

How to Implement Shift Left Testing: A Step-by-Step Guide

Shift left testing is a game-changer for development teams. Steps to Implement Shift Left Testing

Step 1: Start testing early

Instead of waiting until the end of a sprint to test the finished product, I start testing individual components as soon as developers finish building them. This could be a single-user story, a new API endpoint, or a component of the UI. The key is to test in small chunks, not the fully integrated system.

Step 2: Automate as much as possible

Automated tests are essential for shift left testing. I focus on writing unit tests, API tests, and simple UI tests that can run quickly after each code commit. This allows the team to catch issues early when they're easiest to fix. Manual testing still has its place, but automating the repetitive stuff means I can spend more time on complex scenarios.

Step 3: Provide fast feedback

The whole point of shift left testing is to get feedback from developers as quickly as possible. As soon as an automated test fails or I find an issue during manual testing, I report it right away. Bugs found within a day of being introduced can often be fixed in under an hour. If we wait a week or two, it might take several days to fix the same issue!

Step 4: Collaborate closely with developers

Shift-left testing works best when testers and developers work together closely. Regularly pair with the developers to review user stories and discuss testing strategies before coding even begins. This helps ensure you will build testability and quality into the software from the very start. As issues come up, you can work together to troubleshoot and determine the best solutions.

By following these steps, shift left testing has become second nature for your team.

Shift Left Techniques

There are a few useful techniques for implementing shift left testing:

  • Unit testing: Developers write and execute automated tests to validate small units of code. Testers can review and provide feedback on unit tests.

  • Test-driven development (TDD): Developers write tests before writing code. The tests drive the design and implementation.

  • Behavior-driven development (BDD): Teams specify software behaviors as test cases, then implement code to pass those tests. Testers help define expected behaviors.

  • Pair testing: Testers and developers work together in close collaboration to execute tests, discuss results, and make changes.

  • Test automation: Automating regression tests allows testers to focus manual testing on new functionality. Automated tests can be executed earlier and more frequently.

Shifting testing left has many benefits and leads to higher quality, more collaborative development.

How to Convince Management to Support Shift Left Testing

Convincing management to support Shift Left testing can be challenging, but it's worth the effort. As a tester, I've seen firsthand how it improves quality and saves time. Here are a few arguments I've used to win over executives:

Shift Left testing finds bugs earlier, reducing rework. When issues surface late in development, it often requires revisiting old code and wasted effort. Detecting problems sooner means simpler fixes and less wasted time.

  • It lowers costs. The earlier a bug is found, the cheaper it is to fix. Studies show the cost to fix a defect found during requirements or design is a fraction of the cost of fixing that same bug after release. Shift Left testing reduces expensive late-cycle fixes.

  • It speeds up delivery. When testing starts earlier, issues are resolved faster. This smooths the path for new features and accelerates release cycles. Teams can ship quality code at a quicker pace.

  • It improves customer satisfaction. By uncovering more defects pre-release, we reduce unpleasant surprises for our customers after launch. Shift Left testing leads to higher quality products and happier users.

  • It boosts team morale. For testers, finding and reporting issues sooner leads to greater job satisfaction and motivation. Developers also appreciate the opportunity to resolve problems when code is fresh in their minds. Morale remains high when quality is built in from the start.

To summarize, Shift Left testing saves time and money, speeds up delivery, improves customer happiness, and boosts team spirit. While it may require an upfront investment, the long term benefits to quality, productivity and employee motivation make it worthwhile. I encourage you and the leadership team to consider how we can adopt this approach and start reaping the rewards.

Common Myths and Misconceptions About Shift Left Testing

As someone who has worked in software testing for a few years now, I’ve heard a lot of myths about shift left testing that simply aren’t true. Here are a few of the most common ones I’ve come across:

#“Shift left testing requires specialized skills.”

This isn’t the case at all. While shift left testing does require some training on agile methods and tools, the actual testing activities are similar to traditional testing. You don’t need highly technical skills to get started. With some practice, anyone on a software team can pick it up.

“Shift left testing takes too much time.”

On the contrary, shift left testing saves time in the long run. Finding and fixing bugs earlier is much more efficient than waiting until final testing stages. Although it may require more upfront planning, the time savings further down the line more than make up for it.

“Bugs found during shift left testing aren’t important.”

All bugs matter when it comes to software quality. Shift left testing aims to detect bugs as early as possible, regardless of severity. Minor issues detected early on could point to bigger problems that emerge later. It’s best to address any and all bugs, no matter how small they seem.

“Shift left testing requires major changes to process.”

While shift left testing does involve some adjustments to workflow, the changes are relatively minor. Things like increased collaboration, short feedback loops, and a focus on incremental development are easy to implement. Shift left testing complements agile methods many teams already use.

The key takeaway is that shift-left testing debunks many of the myths about software testing. With an open mind and willingness to adapt, any team can reap the benefits of this approach. The small changes required to get started will pay off in a big way.

#FAQs: Answers to Your Most Pressing Shift Left Testing Questions

Here are some of the most common questions along with answers.

1. What exactly is shift left testing?

Shift left testing means starting your testing activities earlier in the development process, rather than waiting until the end. The main goal is to detect bugs and issues as early as possible. This could mean starting unit testing when developers are still writing the code, doing integration testing as soon as components are ready to connect, and doing UX testing with low-fidelity prototypes. The earlier you find problems, the cheaper and easier they are to fix.

2. What are the benefits of shift left testing?

Some of the biggest benefits of shift left testing are:

  • Catching bugs early. Finding defects in requirements, design, and development stages is much more cost-effective than finding them in production.

  • Improving quality. By testing early and often, you can improve the overall quality of the product.

  • Reducing rework. Detecting issues early minimizes the amount of redesign and recoding needed.

  • Faster feedback. Getting feedback from tests and users early in the process allows teams to make adjustments quickly.

  • Less wasted effort. Building the right product from the beginning avoids wasted time building the wrong features or fixing problems later on.

3. What types of testing are considered "shift left"?

Some examples of testing techniques that shift left include:

  • Unit testing - tests individual units of source code as developers are writing it.

  • API testing - tests application interfaces as backend components are being built.

  • Prototype/UX testing - gets feedback from users on low-fidelity prototypes before development starts.

  • Requirements analysis - reviews and validates requirements with stakeholders early on.

  • Risk-based testing - focuses testing efforts on the riskiest parts of an application first.

  • Model-based testing - uses models of the system to generate test cases, even before the system has been built. Read FreeCodeCamp’s Article on Model-Based Testing.

4. How do I get my team on board with shift left testing?

Some tips for adopting a shift left testing approach:

  • Educate your team on the benefits of early testing. Explain how it leads to higher quality, lower costs, and less rework.

  • Start small by shift left on one project or product first. Get some wins to build support for the approach.

  • Align incentives and KPIs to support early testing. For example, reward developers for implementing unit tests or UX designers for getting prototype feedback.

  • Make shift left a team effort. Engage developers, UX designers, testers, and business analysts to build a culture of continuous testing and feedback.


So there you have it, the basics of shift-left testing and how to put it into practice in your own work.

Finding and fixing bugs earlier saves so many headaches down the road. And by making testing a collaborative process between dev and QA, you’ll build better software and a shared sense of ownership in the outcome.

Shift-left isn’t just a buzzword, it’s a smarter way of building tech.

Happy Testing!