What is Shift Left Testing?

In the fast-paced software teams, “shift left” testing is revolutionizing the way they approach quality assurance. This proactive testing methodology is not just a trend; it’s a strategic approach that embeds testing early and often in the development lifecycle, bringing significant benefits to the table.

Shift left testing is a software testing approach that focuses on running testing activities from the early stages of SDLC. This literally means shifting the testing phase to the left-hand side, often represented as the starting point in project timelines.

Traditional testing approaches, such as the waterfall methodology, works with the idea of testing a product once it's fully developed. Simply put, it aims to identify issues in software just before market release. Shift left testing flips this definition by moving testing activities much earlier.

For instance, shift left testing pushes for writing and running more unit tests and conducting integration tests, more often, rather than heavily relying on specific functional tests, end-to-end tests, or UAT tests (performed at the end of the SDLC). It’s geared more towards early identification and resolution of issues, thereby preventing the escalation of minor glitches into major roadblocks, especially at the end of a project.

Also Read: Unit Testing vs. Integration Testing

Shift left testing has several benefits. Here are some notable ones:

Helps Identify Errors Much Earlier

Testing activities from the start of SDLC help detect bugs early to fix them with faster bug life cycles. This helps build a solid foundation for a quality-assured end product.

Saves Dollars and Reduces the Complexities of Bug-fixing

Resolving issues during the development phase is far less complex and substantially cheaper due to fewer dependencies and overheads, as compared to addressing them post-production. This helps save tons of money in the long run and reduces the complexity of bug fixes.

Reduces Time-to-Market

Once you’re sure about the integrity of software, you can release them much faster to the market on set deadlines.

Lowers the Chances of Unexpected Setbacks

Testing software early and frequently minimizes the chances of getting stuck with unforeseen setbacks during product release and post-production.

Improves Collaboration and Feedback Loops

The shift left approach is a team-driven process. It engages cross-functional groups — comprising developers, testers, analysts, and stakeholders — throughout the SDLC. This facilitates transparent and adaptable communication among team members, enabling early and proactive bug fixes.

That’s a good question. There’s no doubt on how useful “shift left” is while testing software. However, there are situations where traditional testing or the shift right approach outshines shift left. Here’s a brief overview of some:

• End-to-End Testing — It evaluates software from start to end. It helps detect any functional issues in software workflows. These tests are typically performed at the end of the development cycle.
• User Acceptance Testing (UAT) — UAT aims to validate the system’s readiness for deployment and use by the end users. Shift left testing isn’t beneficial while running UAT tests since it’s usually performed just before market release.
• Other Scenarios — Sometimes it's not possible to draw correct conclusions or work on assumptions about a software function until it's fully developed for testing. Such scenarios are not feasible to cover with shift left testing.

Also Read: STLC: Getting Started with Software Testing

Here are the shift left testing types:

Traditional Shift Left Testing:

This approach involves testing from the very beginning, including validating requirements and designing documents before any code is written. For instance, creating test scenarios for login functionalities while defining the login page requirements.

Incremental Shift Left Testing

This approach breaks down the development process into smaller chunks. Each chunk is then thoroughly tested before moving on to the next one. An example could be testing the "add-to-cart" function before working on the "checkout" functionality in an e-commerce application.

Agile/DevOps Shift Left Testing

This approach involves running software tests side-by-side and in conjunction with the development lifecycle. With every code change, automated tests run to verify and validate the functionality. An example is automatically running a suite of tests on a new "search" filter functionality to ensure it doesn't break existing features.

Also Read: QA Best Practices in Agile

Model-Based Shift Left Testing

This approach leverages models to predict system behavior with new changes before they are implemented in the production code. For instance, creating a simulation of the entire payment process using a model before integrating a new payment gateway into an e-commerce app.

Here’s a list of best practices while running shift left testing in Agile:

Include Testers From the Start

Shift left aims to include testing from the start. Including testers from the requirement gathering and analysis phase helps to get an in-depth understanding of the project’s scope, objective, and user-centric product mindset.

Practice Test-Driven Development (TDD)

TDD requires writing test cases and test scripts before the actual code is developed. This pushes developers to write software with testable code. It might sound like an overhead, but it ultimately saves you from future headaches and minimizes unexpected issues.

Automate Whenever Possible

Automation can reduce the chances of regressions while performing repetitive and long-running tasks. Automation tools can significantly catapult shift left testing efficiency when performed alongside the development process.

Also Read: Top Automation Tools in 2024

Leverage CI/CD Pipelines w/ Version Control

CI/CD pipelines work with the principle of continual improvement and to update software. Shift left brilliantly aligns with it, especially with agile frameworks. Testing can be performed from the start by leveraging these CI/CD pipelines. It integrates quality checks with version control platforms like GitHub and GitLab throughout the SDLC. This streamlines the development toolchains and reduces complexity and error in later phases.

Also Read: GitHub vs. GitLab

Conduct Security Testing w/ Shift Left

Remember to run security tests with the shift left approach to identify security loopholes and vulnerabilities from the early testing phases. This lowers the chances of getting brick-walled due to security problems later down the road with a fully-fledged system.