Throughout the development and maintenance of an application, there are bound to be changes that will affect or utterly stop already functioning features from working. In software development, this is referred to as a regression bug (a bug is any unexpected error).

In this article, we will talk about regression bugs and how to catch them in our early builds. Let's get started.

What are Regression Bugs?

Regression is the introduction of changes to your application that can affect already working features/functionality in an unexpected way. Just like all other software development bugs there are quite a few causes for regression bugs, some of which are:

1. Failing to get all the necessary requirements of an application
2. Errors caused be dependencies
3. Technical errors
4. Typographical errors

This list is endless. Regression bugs or software development bugs in general are usually unavoidable when developing software applications as there's no such thing as a bug-free software. However, there are common ways that can help keep regression bugs to a minimum.

Let's look at ways to reduce regression bugs in our applications:

Writing Unit Tests

Unit tests involve testing individual "units" of an application, the main objective of writing unit tests is to make sure that each unit (individual function) of our application is working as expected.

By writing unit tests, developers can easily spot bugs and fix them before they break any other already functioning feature, thereby reducing regression bugs.

Using Linters

A lint, or a linter, is a static code analysis tool used to flag programming errors, bugs, stylistic errors and suspicious constructs.

A linter is a tool that scans your source code, analyzes it for better quality, and points out errors that can lead to serious bugs. Linters can even flag warnings and bad practices.

For building web applications, the most common linters are JSHint and ESLint. Both can be used on the command line, but we can use JSHint online to easily find and fix bugs in our code. As an example, let's take a look at this code.

const array = [1,2,3,4];

array.forEach((item) => {
  console.log(item);
});

const array = [2,4,5]

By using a linter, we can easily find the bug here and fix it.

Carrying Out Extensive Code Review

Code review, also known as peer review, is a process where one or several peers check or review another developer program or code. The main purpose of a code review is to locate and fix bugs by carefully reviewing the design, conventions, complexity, tests, and even comments.

By carrying out extensive code reviews, developers are able to easily reduce bugs, ensure better program quality, optimizecode for better performance, and improve collaboration between team mates working on the same application.

Regression Testing

Regression testing is simply re-running all tests to ensure that previously functional features are still functioning as expected after every code change. This means regression testing is responsible for making sure the product works fine after new bug fixes or a change in features.

Regression is actually retesting unchanged parts of our application to ensure that changes made to other parts of the application haven't affect the unchanged part. For example, fixing a bug on the login page may break something on the registration page. Regression testing helps spot such errors before deployment.

Regression testing is a type of software test that is usually carried out whenever production code is modified and in new builds. Regression testing is also known as the Verification Method.

Regression testing requires you to run several test cases manually multiple times, which is tedious and time consuming. To be honest, having to run the same tests over and over again for a period of time is no easy job. So, this is where automated regression testing comes in play.

Automated regression testing is usually carried out with the help of a regression testing tool. Instead of running the test manually over and over again we rely on a tool to automate the tests for us, thereby boosting productivity and saving a lot of time that would have been wasted running tests manually.

Automated regression testing is very essential when dealing with software bugs. Not only does it save time, it also helps you provide new features regularly without breaking any other feature(s).

Conclusion

No person or team can avoid early build bugs. The best we can do is ensure we write quality code, carry out extensive code reviews, use Linters to solve common development bugs and avoid bad practices. Finally, make sure you carry out proper regression testing for any new build and automate as much of the process as you can.

I hope you found this article informative and will try out the suggestions mentioned above.