Regression bugs take up developer time and energy and delay the delivery of new features to users. But in today's world, customers expect software to be delivered fast while keeping a high-quality level. They also expect bugs to be fixed quickly and their software requests to be incorporated in product roadmaps. Regression testing can prevent these bugs and help development teams meet customer demands.

Let's take a look at the three generations of regression testing: manual, automated, and AI-driven, and see when it's recommended to use each one. But first, let's clarify what are regression bugs and testing.

What is Regression Testing?

Regression testing is the type of testing that is run to prevent regression bugs. Regression tests are run after changes are made to the software or when a new feature is added, to make sure these modifications did not negatively impact functionality or performance. Thus, developers gain confidence to build and release the software they've developed.

Regression tests can be either unit tests or integration tests, and they are usually a re-execution of test cases that have worked in the past.

What are Regression Bugs?

A regression bug is a bug that causes a feature to stop working correctly after it was already working. Regression bugs often occur as a result of a code or configuration change, like a system upgrade or system patching.

Why is Regression Testing Important?

Finding regression bugs is a resource-heavy process, which can take a long time and requires many hours of developer manual work. Even a tiny code change can break any of the existing product features so many of them may need to be validated in every cycle.

Regression Testing Types

1st Generation - Manual Regression Testing

At first, developers started out with manual testing. This means that engineers had to define and execute tests to cover all of the possible user flows of the product themselves. The advantages of manual testing are mainly the abilities to: test new test cases that weren't thought about previously (exploratory testing), run test types for components that are considered brittle, and provide a quality description of success or failure.

However, manual testing is slow and is considered inefficient.

2nd Generation - Automated Regression Testing

To answer the challenges of manual testing and to enable quick and efficient continuous regression testing, automation was introduced. Automated regression testing entails a test automation tool running the regression tests from your prebuilt testing suite, at a predetermined frequency.

Despite all these advantages, automated regression testing does not offer full testing coverage, as the test plan will only cover the predetermined test cases.

3rd Generation - AI-driven Regression Testing

The most technologically advanced generation of regression testing is AI-driven regression testing. In this type of testing, tests are automatically created. But, instead of developers having to build test cases, scenarios are autonomously generated based on real user behavior. This ensures these tests are the most accurate and relevant and can directly impact the customer experience.

Summing Up: Advantages and Disadvantages of Regression Testing

Each type of testing has its own advantages and can be used in different use cases.

Manual Regression Testing:

Advantages: Enables exploratory testing, enables testing of "brittle" components, enables in-depth understanding of test success or failure.

Disadvantages: Slow, boring, inefficient.

When to Use: UI testing, sanity testing, occasionally to ensure nothing has been overlooked in the testing suite.

Automated Regression Testing:

Advantages: Quick, cost-effective, frees up developers' time, scalable, integrates into the SDLC.

Disadvantages: Rigid, requires setting up a testing suite.

When to Use: Unit testing, integration testing, when introducing new features, after every build, to shift left security.

AI-driven Regression Testing:

Advantages: Combines automation with exploratory testing, covers real user test cases, customer-oriented, frees up developers' time, scalable, integrates into the SDLC, provides visibility into microservices.

Disadvantages: Does not replace manual and automated testing completely (for now).

When to Use: Continuously, after every build, after every release.

To start automated AI-driven regression testing for free, click here.

3 Generations of Regression Testing: Definition & Use Cases