Regression Testing is a form of testing that is performed to ensure that a change in the code of the software does not affect the current functionality of the product. This is to ensure that the product runs fine with new features, bug fixes, or any improvements to the current features. Previously performed test cases are re-executed to check the effect of the update.
Regression Testing is a form of software testing in which test cases are re-executed to check whether the application’s prior functionality is working fine and no new bugs have been added. Regression testing is a black-box testing method conducted repeatedly by running code units to confirm that ongoing code changes do not affect the functionality of the system. Application updates can occur in a variety of ways, including new features, bug fixes, integrations, functionality improvements, interfaces, patches, etc.
Several software design engineers would assert that, as long as key services are evaluated and are capable of delivering results as required, this would be sufficient. While this may be feasible, regression testing may demonstrate to be a great boon at a later point in time, because instead of just ensuring the functionality being tested, it makes sure that there are no other unpleasant surprises.
Even seemingly insignificant changes can result in a complete breakdown of existing functionality. This is why regression testing software is crucial; to determine that no aspect of the system has been compromised by the changed code. It is recommended that regression tests be carried out as often as possible during the life cycle of software development.
Types of regression testing
Regression testing is also conducted through many phases of testing. It is for this reason that there are many types of regression testing, such as:
Unit regression – Unit regression testing is one of the types of regression testing which is conducted during the unit test process, measuring the code as a single unit. It has a limited and centered approach, where complex connections and dependencies beyond the coding unit in question are effectively halted.
Partial regression – Partial regression is done following effect analysis. In this testing process, the new arrival of the code as a unit is used to communicate with other parts of the older existing code. Doing so ensures that even with a code shift, the device operates in the silos as desired.
Complete regression – Complete regression testing is often done when the code changes for alteration or software updates pass back to the roots. It is also carried out in the event of several changes to the current code. It offers a holistic view of the system as a whole and weeds out any unexpected issues. A kind of “final” regression test is carried out to certify that the construct (new lines of code) has not been changed for some time. This final version is then rolled out to end-users.
How Regression Testing is done?
To conduct the Regression Testing process, we need to first debug the code to find the bugs. If the bugs are found, the necessary modifications are made to correct the problem, and regression testing is performed by choosing the appropriate test cases from the test suite that covers both the changed and affected sections of the code.
Rigorous regressive testing is not so much about the number of test cases as it is about the coverage of critical conditions. These requirements ensure that the feature remains, that bug-fixing has been completed, and that a specific functional area can handle unpredictable actions.
Purely performing regression testing in some cases is not very convenient or realistic. For example, although one case can cover several conditions, it may also cover only one of those conditions. There is also no proper estimation of the amount of information that needs to be taken into account during the regression test.
A sequence of steps is given below to explain how exactly regression testing can be done:
Sanity Test – Mostly performed to verify that the system is stable, this check is done to ensure that the system is running under ‘natural’ conditions. Rather than discovering bugs, the goal here is to ensure that the system is stable long before the rest of the testing process begins.
Analysis of requirements – The requirements for improvements or additions to the code must be carefully analyzed. Users also report errors that are found to be the product of last-minute adjustments when analyzed. The customer expectations must therefore be carefully analyzed and the software regression test case prepared in such a way that the core features of the software remain securely intact.
Essential Feature Test Cases – All the different test cases developed for regression testing, the most critical test cases for both consumers and development teams are sanitary test cases that verify the basic functionality of the system. Ordinary setup-related test cases are then reviewed for priority.
Test cases are built for regression testing as the software life cycle advances are then performed as per bandwidth and requirement. In particular, integration test cases are very important and several regression test cases need to be conducted, particularly during integration testing. For instance, an unexpected fix at the last minute can break the compatibility between multiple modules, even in the framework that has already been checked.
Selection of test cases – They can be chosen for execution after the prioritization of the test cases. The selection of these test cases is made mainly based on the field of recurrent defects, the characteristics, and their criticality. Tests are performed vigorously for certain code units that have continuously undergone several changes.
Effective regression techniques and types of regression testing save time and resources for organizations. As per one case study in the banking domain, regression saves up to 60 percent of the time in bug fixes (which would have been caught by regression tests) and 40 percent in cash.