Introduction

Why is regression testing important? Organizations today need an effective regression strategy to save money and time. A case study on the banking domain shows that regression techniques and testing helped save as much as 60% of the time spent on fixing bugs normally weeded out by regression tests and as much as 40% in terms of the money eventually spent use of regression without the use of regression testing. Thus, this tutorial explaining what is meant by regression testing, the purpose of this testing, different types, how is it done etc.

In this article let us look at:

  1. Need for Regression Testing
  2. How to do Regression Testing?
  3. Regression Test Selection
  4. Selecting Test cases
  5. Testing Tools
  6. Configuration Management and Regression Testing
  7. Difference between Retesting and Regression Testing
  8. Challenges

1. Need for Regression Testing

The need for Regression Testing is real whenever any changes to a program or code are made. One needs to test whether the modified/new code affects the other software components or the execution of the software application. Such testing of regression types is also required for adding new features to the application software, defect fixing and performance-related issues fixing.

What is a regression test? Defined in testing, it is a type of testing software using regression techniques to confirm changes in recent code or programs have not affected any running program or existing features (called regression). Here a partial or full selection of previous test cases already executed is rerun again to ensure that all existing functionalities are working well. 

2. How to do Regression Testing?

What is regression testing in software testing? Software and its maintenance is an ongoing activity that typically is frequently done to provide for enhancements, optimization, error corrections and existing features deletion. Since modifications to a program’s code can alter the systems environment and cause it to work inefficiently and incorrectly, Regression Testing is an essential factor for efficient bug-free software and organizational efficiency.

To execute the process of Regression Testing, one needs to find and fix bugs in the code while identifying all its bugs. When all bugs have been found, required changes to the code or program have to be executed to fix the bugs. Testing is then done using a test suite’s relevant and selected test cases. The test suite typically contains both the affected and modified code parts. It can be done using the technique of “Retest” described below.      

The retesting all method of Regression Testing especially used when the suite, test-bucket has all the tests that need to be re-tested involves expending of resources, money and time. 

3. Regression Test Selection

Regression Test Selection uses testing techniques with a select batch of test cases from a suite of tests, which are run to check if the changed code impacts the working of the remaining code or software application. Test cases are subdivided into obsolete test cases (These tests cannot be used for further and succeeding cycles.) and reusable test cases (These test cases can be used for further cycles of testing.) cycles. The prioritization of cases is based on the frequently used applications, critical functionalities and business impact. Normally the selection of priority-based cases reduces the test suite for regression testing.

4. Selecting Test cases

Selecting test cases for regression testing is not easy. It is an art since most defects that were reported by industry data were last-minute fixing of bugs and affected the application showing unwanted side effects. Selecting the following testing tools and test cases ensure efficient regression testing.

  • User functions that are visible when using the application.
  • Test cases with frequent defective behaviour.
  • Verification of product core features test cases.
  • All test cases involving the integration of code and property.
  • Cases in the testing of recently tested and changed functionalities.
  • All complex cases of testing.
  • Successful test case samples.
  • Test cases for boundary values.
  • Failed cases of test samples.

5. Testing Tools

When the software changes frequently, regression testing costs escalate. Plus, the manual running of these testing cases increases the costs and time spent in execution. Automation is a smart choice for test cases in regression since it reduces both the time and costs. The amount of automation will depend on the volume of re-usable test cases left for the repetitive regression cycles. Let’s discuss the important software engineering regression and functional testing tools.

QTP or Quick Test Professional: The automatic suite for test cases both functional and regressional in HP’s QTP suite is a regression testing example that uses automated software based on the Visual Basic language script for its implementation. This tool is a keyword-based tool that is data-driven. 

Selenium: This tool is open source and used in the automation of several web applications and for regression testing, which is browser-based.

RFT or Rational Function Test: IBM’s Java tool, the RFT automates the test software application’s cases. Used primarily as a test case in regression, it integrates with another powerful tool, the Rational Test Manager. 

6. Configuration Management and Regression Testing

Regression Testing’s configuration management is critical and imperative in an Agile environment where the code undergoes continuous modifications. Factors that make regression tests effective are

  • Using a tool for configuration management when code is being regression tested. 
  • The testing phase of the regression test should not allow code changes since the regression test codes need to be developer changes independent.
  • Isolate the testing database to prevent changes to the database.

7. Difference between Retesting and Regression Testing

The primary difference is that ‘Retesting’ happens when the testing of the bug or the functionality is repeated again and again till the defects are plugged. Retesting repeats when the bug is not addressed. It is reopened and retested until the defect is plugged. 

Regression testing, on the other hand, is used to test the software application whenever it suffers a prop or code change since other parts of the software should not be affected by running the new code.

8. Challenges

These challenges are major issues or problems in Regression Testing.

  • The test suite becomes large with successive runs of regression. Due to budget constraints and time, the entire test cases in the regression test suite may not be executed.
  • Ensuring maximum test coverage while keeping the test suite to a minimum is always a challenge.
  • The frequency determination of tests for regression remains a challenge. When should regression testing be performed? Should it be when an update or modification happens or after a bug has been fixed? 

Conclusion

When to do regression testing? It is crucial to ensure the latest code changes have no side and detrimental side effects on the existing programs and functionalities while ensuring the old code works well when the latest code changes are implemented. It is needed to test whether the modified/new code affects the other software components or the execution of the software application, for adding new features to the software application, defect fixing, performance-related issues fixing and to define regression testing.

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