What is Regression Testing?
Regression testing is a type of software testing which ensures that previously developed and tested software application working in the same way as it was working before recent code/configuration changes done.
In this testing, test cases are re-executed in order to check whether the earlier functionality of the software is working as projected and the new configuration/code changes have not introduced any new issues/bugs.
Understand Regression Testing with Example:
Regression testing is the process of re-running both functional and non-functional tests to verify that a coding change or new program has not affected the software’s existing features and functionality. Sometimes adding in or changing code can cause errors to arise and adversely affect the workings of other code.
This type of testing is done so that the testers can keep track of the working builds and note exactly which new change or feature had unexpected side-effects. Regression testing should be done after fixing any bugs to ensure that the fix hasn’t caused any additional problems. This allows the testers to easily track the problem and fix it.
A website has a feature that allows you to upload images in JPEG and PNG format but there is a bug causing one of the formats to fail to upload. When a developer fixes this bug, a regression test must be performed to ensure that the fix hasn’t affected the other features involved in the image-uploading process.
Need of Regression Testing:
This testing is required when there is any:
- Change in requirements and code is modified as per the changed requirements
- Added new features in product
- Bug fixing
- Fixing of performance related issues
What are the techniques of Regression Testing?
Continuous software maintenance includes lot of activities such as enhancements, error corrections, optimization etc. Due to these new changes system may start to work incorrectly. In this case regression testing is required to handle to new generated issues. this testing can be performed using following techniques:
- Retest All: Re execute all the tests in the existing test bucket. This requires huge time and resources and that’s why it is very expensive.
- Regression test selection: Execute the selected part of test suites i.e. re-usable test cases or obsolete test cases.
- Test case prioritization: Prioritization of test cases depends on business impact and used functionalities.
Benefits of regression testing
The basic idea of conducting this testing is to identify issues that might have got developed because of the changes applied, In this case conducting regression testing benefits in a number of ways such as:
- Increase possibilities of tracking bugs caused due to new changes
- Helps in researching unwanted side effects that might have been occurred due to new operating environment
- Identify bugs and errors in early stage
- Extremely valuable in situations when constant changes are required in the product
Types of Regression Testing:
Corrective regression testing is used when there are no changes introduced in the existing software/application/product specification. The existing test cases can be used to conduct the desired test.
This testing is used in situations when the modifications are added in the specifications of the product and new test cases are designed. Progressive regression testing works effectively when there are changes done in the software/application specifications as well as new test cases are designed.
We utilize a subset of the current experiments to cut down the retesting cost and effort in selective regression testing. In this case if any changes are done to any part or module of software application/product, e.g. capacities, factors and so on and afterward a test cases must be re-executed. Here is the difficult part to determine the conditions between an experiment and the program elements it covers. It is done to observe the effect of new code development to the existing code of the application. When this type of relapse testing is directed, a subset from existing experiments is utilized, to reduce the effort needed for retesting.
Retest-all strategy is very time taking because in this testing we reuse all tests which results in the execution of avoidable test cases. This strategy is not much useful when any small modification or change is done to the application. Retest-all strategy involves the testing of all aspects of a particular application as well as reusing all test cases even where the changes have not been made. This testing is not advisable when there is a small change in the existing code.
Complete regression testing is very useful when multiple changes have been done in the existing code.This testing is specially used when multiple new changes has certain impact on software’s root code. Performing this testing is highly valuable to identify unexpected bugs.
Best Regression Testing Tools:
If you have software which undergoes frequent changes or modifications then regression testing costs will escalate. In this case, manual execution of test cases increases the time as well as cost of test execution.
There are many regression testing tools available that could help in execution of tests in this testing and reduce the execution time and cost.
Below is the list of most important regression testing tools that can be used for both functional and regression testing:
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