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Here’s the TL;DR: Shift-left testing is an approach to testing and test automation in which test activities are done earlier in the software development lifecycle (SDLC).
That’s why it’s called shift-left—because if you imagine the SDLC as a line that goes from left to right, then things on the left happen first.
The benefit of this approach is that you reduce the overall costs of your software quality assurance by catching defects earlier in the process, when they are cheaper to fix.
Implementing shift-left testing involves test automation, cross-functional collaboration, and, above all, a cultural shift across the organization.
What Is Shift-Left Testing?
Shift-left testing is an approach to software testing where testing ceases to be a phase that you do after all development work is over, and instead becomes an activity that you perform as early as possible and continuously.
When shifting left, you should leverage automation to the fullest, generating a test suite with comprehensive test coverage that you can then run on demand.
The Benefits of Shift-Left Testing
In traditional testing, defects are caught late in the whole process, which makes them harder to fix. Also, the testing phase would often uncover profound problems with requirements, such as them being misunderstood or completely missed.
Shift-left testing addresses the problems above. Since you’re testing earlier and continuously, you’re way more likely to catch defects sooner.
But what about the requirements problem? Well, shift-left testing isn’t only about test automation, though that plays a key role.
Another crucial component of this new approach to testing is collaboration. You bring together stakeholders to collaborate on the quality effort earlier, making these requirement issues go away.
Regression testing problems are also addressed by automation. When shifting left, you should leverage automation to the fullest, generating a test suite with comprehensive test coverage, that you can then run on demand.
That way, you catch regressions instantly instead of your users finding them in production.
How Does Shift-Left Testing Differ From Other Forms of Testing?
Let’s examine the ways shift-left testing is different from the rest of the ways you might test.
Shift-Left vs Waterfall-Like Testing
Shift-left testing stands in direct opposition to waterfall-like approaches to testing. As you’ve seen, older approaches to software development approached a project in terms of sequential phases. And testing was commonly placed near the end of this sequence.
Shift-Left vs Shift-Right Testing
Another emerging trend is shift-right testing. The name makes it sound like it’s the opposite of shift-left testing, right? Is shift-right testing just a fancy name for the waterfall-like testing you’ve just read about?
Actually, no. Shift-right testing is a very modern approach to software quality. The idea here is moving testing and other quality activities towards production or production-like environments.
These are some techniques that can be used in shift-right testing:
- Post-deployment smoking tests
- Load testing in production
- Chaos engineering
- Deployment techniques such as blue/green deployments, canary rollouts, and feature flags.
- Synthetic monitoring, real-user monitoring, and other monitoring techniques
You could argue that some of these stretch the concept of “testing.” And that’s a fair point. The term is used loosely.
But the idea of shifting right is basically to employ quality techniques and mechanisms that don’t make sense to apply to testing environments. They really shine when applied to either prod or a prod-like environment.
All that is to say, shift-right testing, far from being the opposite of shift-left testing, is something you can and should adopt alongside it.
Types of Shift-Left Testing
There aren’t really “types” of shift-left testing, strictly speaking. Shift-left testing isn’t a new type of testing. Rather, it's a different mindset or approach to testing.
Shifting your testing left means changing the way your organization thinks about testing, who does it, and how and when they do it.
Let’s talk about some different types of testing and how to apply the shift-left thinking to those types.
Shifting your testing left means changing the way your organization thinks about testing, who does it, and how and when they do it.
Unit Testing
Unit tests are automated tests written by programmers alongside the code they’re writing for their features. It is, by definition, one of the earliest types of testing you can do.
Integration Testing
Programmers often also write integration tests, in which you don’t stub out most of the dependencies but use real dependencies.
Shifting integration testing left means writing those as early as possible so you can catch bugs that hide in the edges of two systems interacting with each other.
Acceptance Testing
Acceptance testing is where the collaboration aspect of shifting your tests left shines.
You can involve QA analysts, business analysts, and even the customer/end user, when feasible, to collaborate on defining acceptance criteria, BDD (behavior-driven development) scenarios, and requirements.
End-to-End Testing
All this talk of testing earlier might make it sound like end-to-end (E2E) testing doesn’t have a place in shift-left testing. That is not true.
Within this approach, E2E testing continues to be important. After all, you still need to ensure all pieces of the puzzle fit together. But E2E testing is now informed by the earlier tests, so you can decide to focus it on a narrower slice of functionality, covering primarily the most critical areas.
So, E2E testing doesn’t go away when you shift left. It becomes more efficient.
How to Get Started With Shift-Left Testing
Here are the steps to get started with shift-left testing.
Start With Unit Tests/Integration Tests
These are tests owned by developers. They should write them alongside their code. This has the greatest ROI for shifting left, since it doesn’t require you to invest in any tools that developers don’t already have.
Involve QA and Other Stakeholders Earlier
Waiting until development is done to hand off tests to QA feels very waterfall. Instead, involve QA, business analysts, and other stakeholders early.
Have them collaborate on defining acceptance criteria, requirements, and BDD scenarios. If feasible, have QA analysts pair with developers during development.
Invest in Test Automation and Leverage AI
You’ll want to enroll people with no coding skills in the test automation effort. For that, you need to invest in a good codeless test automation tool. This will let non-technical people write and maintain tests without writing code. Otherwise, developers become the bottleneck for this.
You can and should also leverage AI, which can be a great way to let even more people collaborate with the test automation.
For instance, Autify Aximo is an AI testing agent that can, among many other features, generate test cases from plain English prompts and user story requirements/acceptance criteria.
A good codeless test automation tool will let non-technical people write and maintain tests without writing code
Challenges of Shift-Left Testing
Shift-left testing is far from being a bed of roses. Here are some challenges you might face.
1. Initial Upskilling Cost
To make all of this happen, people will need skills that they might not currently have. This requires at least some upfront investment in upskilling people, along with the time needed to do so.
2. Test Maintenance Burden
Test maintenance can quickly become a burden, especially when test automation is done using tools that create brittle tests that break easily. A way to address this, again, is leveraging AI tools with which you can create self-healing testing suites.
3. Cultural Resistance
The hardest challenge you’ll come up against isn’t a technical one. At first, people will likely resist the new trend.
Developers might not want to collaborate with stakeholders. QA people might be used to only being handed down a list of features to test, and they’ll refuse to get involved earlier. The list goes on.
To counter cultural resistance, you usually need lots of training and, most importantly, leadership buy-in.
Is Shift Left Testing the Way Forward?
Organizations are often looking for ways to cut costs. And there’s a great way to do that: investing in quality.
That way, you don’t find bugs late in the process, when they’ve already made it to production and are costlier to fix. That’s exactly the scenario that shift-left testing aims to prevent.
Hopefully, after reading this guide, you are now convinced that shift-left testing is the way forward and are ready to implement it.
If that’s the case, you might take a look at Autify Aximo, the AI testing agent that can help you scale test automation across your organization, without the need for coding skills and with zero maintenance.
Thanks for reading.
FAQ
What Is The Difference Between Shift Left and TDD?
Shift-left testing is the overall approach of moving testing activities to the beginning of the software development lifecycle and doing them continuously.
TDD (test-driven development) is a software development methodology in which you use automated unit tests to drive the implementation of the features. TDD is often used as one of the techniques for shift-left, but it’s not mandatory.
How Does Shift-Left Testing Relate to Agile?
Agile preaches developing software in short iterations. Thus, it’s completely against testing being a fixed phase after a long implementation phase.
More specifically, there is a particular “flavor” of agile software development, called extreme programming, or XP, in which TDD (test-driven development) is a core practice. So, we can say agile is highly compatible with the ideas of shifting left.
What Is The Difference Between Shift-Left and Shift-Right Testing?
Shift-left testing is moving testing activities to the start of the SDLC. Shift-right testing means applying some quality techniques to production or production-like environments. They are not opposites; rather, they complement each other.
Can Shift-Left Testing Work in a Waterfall Environment?
Nothing stops a team from doing testing activities earlier and often, even in a waterfall-like environment, as a replacement or complement to a formal testing phase. But shift-left testing would act as the catalyst of the organization, ultimately moving out of waterfall-like processes.
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