Shift-left testing was coined by Larry Smith in 2001, in which testing is performed earlier in the software testing life cycle, essentially "shifting" it to the left of the timeline. Ever since, shift left testing has been widely adopted by software testing teams worldwide to catch and address bugs as early as possible.
Why shift-left testing?
The longer a bug is left untreated, the more deeply it is entrenched into the code. It gets increasingly more costly and difficult to fix these bugs because there are too many dependencies on them by the time they are found.
In the past, testing is only done once all development is done. This leaves QA teams with little to no time to test properly, and even if a bug is found, the devs don't have enough time to fix it either. This way of working is not efficient.
Instead of waiting, shift-left testing brings testing into the same time frame as development. This means:
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Developers test their code as they write it (unit testing, static analysis).
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Testers work with product managers during requirements gathering to design test cases early.
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QA doesn’t wait for a feature to be “done.” They’re involved from the start. That means running exploratory, integration, or automation tests alongside ongoing development.
How to implement shift-left testing
How shift-left testing is implemented ultimately varies from organization to organization. At its core, the philosophy stays the same: doing everything as early as possible to shorten time-to-market.
It's up to you to define "how far" you may want to go. Redditor u/accidentalciso in the r/cybersecurity subreddit shared that they once even did QA a year and a half before the project officially starts.
For other QA teams, shift-left testing may be as simple as involving QA from the requirements study phase and design to give them better context on what they should be doing later down the road.
We'll show you how QA is involved across the stages.
1. Establish the shift-left mindset
Since shift-left testing does not happen in just the QA team, there must be a mindset shift across the organization. Quality is the responsibility of neither the devs nor the testers, but rather, of everyone.
To prepare for shift-left is to understand that:
- Quality is baked into every stage from ideation to deployment
- QA becomes involved early but as risk analysts, collaborators, and scenario designers
- Developers think about testability and failure cases while writing code
- Product managers and designers consult QA and engineering early to reduce ambiguity and oversights
To ensure a smooth transition, host a meeting to align the team members on the same vision. In that meeting, discuss the ways in which you can involve QA early.
Below are some examples.
2. QA involvement in pre-development stages
QA can also be involved in the pre-development review stage.
At this stage, the Product team presented the feature idea, the user flows, or UI states for feasibility and architecture check. Testers can step in here to review the user story and design through the lens of behavior and failure.
That fresh perspective is what makes early QA involvement valuable. They prevent potential issues even before development begins.
QAs can write test cases at this case already, not the specific ones, but the high-level ones. It triggers the entire team's thinking process. Writing test case, in essence, is a brainstorming activity that requires you to dissect the inner working of the feature, and in the process you may come up with unexpected scenarios for both development and testing later down the road.
Only when the engineering team have fully analyzed the story, accepted it, with all questions answered and all issues clarified do the team proceed to development.
3. QA involvement in parallel with development
Shift-left didn’t stop at planning. During development, QA team starts writing end-to-end automated tests in parallel with feature implementation. This meant automation was ready to run the moment the feature was stable.
These tests are later turned into regression test suites. In future sprints, when new features are available, you already have automated regression test suites ready to run right away. This means:
- No testing bottlenecks at the end
- Faster feedback
- CI pipelines became truly effective
4. Remove the bureaucracy
Shift-left testing sounds long and heavy, but it shouldn't be. This ties up closely with the first point we mention: establishing the quality mindset. It is important to align across all teams on the benefits of the approach. It makes everyone's lives easier because it helps to:
- No more debates mid-sprint about how things should work
- No more chasing down missing error states (they have been addressed in the earlier discussion)
- No more QA being a bottleneck
- No more features being unclear
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