5 Key Differences to know about Regression Testing and Retesting
Tags: retesting, regressiontesting, testgrid
Published: 2024-06-14 10:28:53

As you must be aware, depending on the stage of development, various types of testing are undertaken during the multiple phases of the software development life cycle (SDLC). Each level of the SDLC has its own set of requirements and objectives for testing to meet.
Unit testing is followed by integration testing, system testing, system integration testing, acceptance testing, and regression testing in the testing phase.
There are many distinct sorts of tests in software testing. However, due to their likeness and apparent overlap in purposes, people often misunderstand them. Regression testing and retesting are two ideas that are frequently misunderstood. They have comparable sounds and similarities which cause confusion.
But, are they similar?
If not, then what are the differences between them?
A detailed comparison is what we need to clear these doubts between regression testing and retesting.

## What is Retesting? 
The term “retest” refers to the second round of testing. It makes no difference what the reason is. You retest when you repeat a test. You could retest the functionality of the current version. Or a bug fix, functionality from a prior version, a test case you just ran, and so on.
If you’re still perplexed as to why then consider the following arguments:
●Yesterday, you did a test and discovered a flaw. You want to make sure the steps and the defect are repeatable. As a result, you retest.
●You performed a test. But, you weren’t paying attention to it. You want to double-check, so you retest.
Retesting is the process of repeating a test for any specific reason. It’s one of those words that means what it says.

##  What is Regression Testing?
Regression Testing is one of the types of black-box testing. It ensures that any changes or additions to the existing code base do not negatively influence features that have already been developed and tested.
Regression testing ensures that the application continues to function as expected after a modification. Regression testing falls into two types called smoke and sanity testing. When performing regression testing, you run both functional and non-functional tests. A new module is never subjected to regression testing.

Read also: [Regression Testing: Complete Guide](https://testgrid.io/blog/regression-testing-complete-guide/)

## What Does Regression Testing Aim to Achieve?

The whole point of regression testing is to make sure that new code changes do not negatively influence the application’s previously created and tested functions.

### When is it Necessary to Conduct Regression Testing?

- Testers perform Regression testing in any of the following situations: 
- When a client submits a change request (CR), the code base undergoes alteration.
- In cases, where the testing environment undergoes a change.
- When you move the back-end code to a new platform.
- During the testing process, the developer discovers a critical bug and rectifies it.
- An existing software gets a new feature.
- The developers have addressed the essential concerns about performance difficulties and crashes.
- Fixes have been added to the patch.

- For a better user experience, the application’s UI underwent modifications. 

### Explaining the Difference Between Regression testing and Retesting
To demonstrate the distinction between regression testing and retesting, consider the following example:
Consider the following two possibilities.
Case 1: Login Page – Login Button that is not working (Bug)
Case 2: Login Page – Added a checkbox to “Stay signed in” (New feature)
In Case 1, the login button isn’t working. Therefore the tester files a bug report. After the repair of the bug, testers check to see if the Login button is functioning as expected.
In Case 2, the tester evaluates the new feature to check it works as intended (Stay signed in).
Retesting applies to Case 1. Here, the tester retests the bug discovered in the previous build by following the steps outlined in the bug report.
In Case 1, the tester also does regression testing on features linked to the login button.
Case 2 falls within the category of regression testing. Here, you test the new feature (Stay signed in) as well as the associated functionalities. Regression Testing is the process of testing relevant functionalities while also testing new features.
Another Example
Consider the following scenario:
An application under test contains three modules: administration, Purchase, and finance. The Purchase module is dependent on the Finance module. Suppose a tester discovered and reported an issue in the Purchase module. Once the tested rectify the bug, he must perform Retesting. This will ensure the resolving of the bug related to Purchase. Regression Testing tests the Finance module that depends on the Purchase module.

## Comparison between Regression Testing and Retesting

### What do they have in common?

- Validation and Black box testing methodologies are both based on repetition.
- Both automated and manual test cases undergo retesting and regression testing.

###  What makes them different? 

- Any test – current or prior version functionality targeted – can benefit from retesting. The functionality of previous versions is the focus of regression.
- There is no requirement for retesting if there has been a change. Change is the focus of regression.
- On failed test cases, testers perform retesting, whereas they perform regression testing on passed test cases.
- Retesting ensures the rectification of the original error, whereas regression Testing ensures that there have been no unanticipated side effects.
- Regression testing has a lesser priority than retesting. Testers conduct regression testing parallel to retesting.
- Due to the ambiguity, we are unable to automate the test cases for Retesting. On the other hand, you can automate regression testing.
- Regression testing is generic testing. Retesting is a planned test. Regression is a broad topic with a variety of subtypes. Automation is also a good fit for regression testing. If your team is spending a bunch of time running the same regression test cases over and over, it may be time to automate them. The examples and differences mentioned above give us a better understanding of the differences between Regression testing and Retesting.

Source :_This blog is originally published at [TestGrid](https://testgrid.io/blog/difference-between-regression-testing-and-retesting/)_