Shift Left Testing: How Defining Test Cases Early Can Reduce Bugs

Imagine a team building a new “Add to Cart” feature for an e-commerce app. 

Initially, as they collected project information on features, scope, and deadlines, everything was clear about what needed to be integrated into the app for accessibility. The user journey for purchasing an item also appears straightforward.

“A user visited the app, scrolled, and selected an item to add to the cart, and the items were included, and the cart count was incremented.”

Once developers finish coding, the app passes all radars, and QA takes over in-depth testing. They realize... nobody planned what needs to be tested. 

• What if the network is unavailable or poor?
• What if the user logged out?
• Does the app enable cart synchronization across all devices on which users are logged in?
• Does the inventory automatically show that any items are out of stock?

When any user logs in and clicks to add items, the button works, but the cart doesn’t update correctly, discounts don’t apply, and the checkout fails when the internet is slow. Now the team must go back and rebuild multiple pieces again.

This could have been avoided if QA test cases had been defined beforehand.

It’s good to stick with the basics, but if we still plan to follow the traditional method of initiating testing after the product is fully delivered, it will be a waste of time due to rework.

• What if the finalized product will not align with the expectation
• Discovering the bug or technical bottlenecks later will delay the release
• Not every bug fix requires a minor adjustment; some need to impact the overall library shift, new functionality, or API 

In modern product development, test cases often come after development. But a more innovative approach is “shift-left testing," where testing starts from day one. 

By defining test cases early, everyone understands the expected behavior, scope, edge cases, and success criteria clearly.

Just think about it; you have gathered the project and related ideational information. The prototype and wireframe proposed a well-structured UI/UX, which appears perfect at first glance. 

Developers implemented the required features, but unfortunately, the issues are mounting.

It's all because behavior at each phase was not validated first and moved on to other phases. 

If test cases were planned and validated well along with the requirement gathering, analysis, and UI/UX design phase, teams would get the indicator of whether to rethink and redesign the UI/UX behavior.

Truly, minor negligence leads to a costly mistake.

Defining test cases earlier and following the Shift Left testing method will reduce rework. Instead of ticking the checklist, ensure that every phase is complete and error-free before progressing on the next.

Once, a freelance developer was assigned to develop a logistics platform. Based on the project requirements, he designed an interactive UI/UX and other features. 

During the testing phase, he discovered that clicking a radio button for gender selection selected all values at once, even though only one value should be selected. While this was a minor fix, it was functionalities. actually an issue. 

Later, certain data field values were not being stored in the database. So the developers need to recheck multiple functionality. 

Similarly, one developer once said: 

“I finished the feature, but half the scenarios were never discussed. I had to rewrite most of it.”

So factually, teams that skip early test case planning often struggle with:

• Requirements changed during development because expectations were unclear.

• Developers code based on assumptions rather than facts.

• QA teams not knowing what to validate and where to start.

• Late fixes are causing delays and increased cost.

• Users facing broken experiences in production.

Well, whatever it is, it's not because they have a lack of experience but because of the process gap.

Read more on how our QA team does E2E testing with Cypress automatically.

As AI and automation continue to grow, early test cases planning will become even more

critical. 

Software development teams are actively exploring how all stakeholders collaborative workflows will impact outcomes, working on the same page from day one.

Automated test case generation, requirement-based testing, and API-level validation will run in parallel with development. The future belongs to teams that collaborate from the beginning: Product, QA, and Development working as one.

Beyond compliance in silos, work will start on the first day.