What is regression testing? Talk about regression testing in the eyes of Ali Test Engineers

lately , Some product defects are fed back from production , Development 、 The test conducted a multi-dimensional cause analysis of defects , The escape of defects is caused by many factors in the production process , Part of the reason is the improper selection of regression testing strategies . Here it is , We need to focus on regression testing .
What is regression testing

English name of regression test ：Regression Testing, Literally , yes “ Reverse test ”. This shows that , Software can be divided into current state and original state . Regression testing is the functional and non functional testing of the original state of the software , To ensure that the previously developed and tested software is in defect repair 、 Configuration changes 、 After these changes, such as software updates , Can still meet the requirements of the operation （ namely ： The functions and non functions of those parts that have not been modified in the current state of the software are consistent with the original state ）.

The concept of current state and original state of software mentioned here , We can simply think that , Each version currently submitted for testing is the current state of the software , The previous version is the original state . perhaps , The current baseline is the current state , The last baseline is the original state . How to distinguish , It can be formulated according to management requirements .

Timing of regression testing

Whether based on the development of new products or the maintenance and upgrading of old products , Regression testing is an essential part of a complete test . Usually , The time for regression testing is ：

1） Defect repair

When the developer completes the defect repair of the software in the current state , And submit a new test version or conduct a code baseline ;

2） Software update

After the developers complete the new functions and code refactoring , And submit the test version or conduct the code baseline . among , New functions often correspond to maintenance products , It should be tested completely , That is, the verification test of new functions , And regression testing . For code refactoring , It should be treated with caution based on the principle that the running quality is always higher than the code quality , If you decide to refactor , Then a full regression test must be carried out ;

3） Configuration changes

Due to the flexibility of software parameter configuration and the need of efficient operation and maintenance , To profile 、 Script 、 Batch command 、 After the stored procedure is modified and formally notified to the testing department .

Regression testing techniques

There are usually three techniques for regression testing ：

1） Repeat the full test case

Execute all test cases and check the results of the software in the current state . This technology is due to the re execution of full test cases , It can minimize the risk of defect omission , But the test cost （ Time cost 、 Labor cost 、 Financial costs ） Very high ;

2） Select some test cases to repeat the test

Different from the above , Only execute and check some test cases for the software in the current state . The biggest benefit of this technology is the cost of testing （ Time cost 、 Labor cost 、 Financial costs ） Repeat the test below the full test case ;

3） Test case optimization

The optimization technology of test cases refers to , From the perspective of the scope of test cases, that is, effectiveness and efficiency , Optimize 、 Extract test cases that are useful for subsequent software versions or specific versions （ aggregate ）.

The strategy of regression testing

Regression testing techniques are used to serve regression testing strategies . Usually , We will choose from the following strategies in our daily work .

Full regression testing strategy

In some special industries , Like finance 、 Communication industry , The requirements for the quality of software products in the production environment are usually serious escape defects above the level of 0, In this case , We must use the highest safety factor 、 The strategy with the lowest risk level is tested by regression , To meet the quality requirements . At this time , We can use the full test strategy , Regression testing is carried out by using the technique of repeated testing of full test cases .

The full regression test strategy can be applied to any situation , It is a strategy that is not a strategy , Although effective , But not

Efficient .

Incomplete regression testing strategy

In practice , There will be more and more test cases , The workload will also be increasing , In particular, maintain and update products . When the quality requirements remain unchanged , When there are online time and other conditions , We will choose the incomplete regression test strategy , Use some test cases to repeat the test technology for regression testing . This is also the most common strategy we use .

The core idea of this strategy is to use test case optimization technology , Improve test efficiency , Reduce resources .

But the risk of missed testing of this strategy is also obvious , such as , Testers are weak in code dependency analysis , This can easily lead to the neglect of test cases that may find defects . To avoid this risk , In addition to using test case optimization technology , It should also be combined with business risk driven analysis methods .

Overall , Testers need to communicate with developers 、 Discussion of business personnel , Conduct risk analysis and operation analysis on the tested software , Understanding the software under test is the most important 、 The most frequently used function , That is to know the business criticality and failure probability of the tested software , Then the corresponding test cases are used according to the risk analysis results of these two dimensions （ aggregate ） Optimize the technology for regression testing .

Concrete , In the testing industry, business impact testing is an axiom , therefore , To understand the business criticality of the software under test is the primary task . secondly , The software and its modules have the possibility of failure , The relevant indicators and examples of these two can be shown in the following two tables ：
surface 1： Business criticality indicators and examples

surface 2： Failure probability indicators and examples

Through the above two tables , The risk level of the tested software function model is obtained by combining the business criticality and failure probability evaluation , As shown in the following table ：
Through the above table , Reduce the set of test cases in the incomplete regression testing strategy , Concentrate on the tests you need most , Provides a basis for , So as to reduce the risk of missing measurement . Of course , Regardless of table 1 Or watch 2, The grading requires the experience accumulation of testers , Business people are also needed 、 Strong support from developers .

Automated regression testing strategies

Because regression testing is an iterative process , Usually when we mention regression testing , Will consider using automated methods . therefore , The extracted test cases can be maintained by using test case optimization technology 、 Reuse 、 Automated steps to build an automated regression testing platform , This method is applicable to maintenance classes 、 Upgrade software （ such as ： Market surveillance 、 Settlement system ） The regression test can be effective and efficient .

however , To achieve the goal of using automated regression testing strategies , Special personnel are needed to implement , Driven by business flow 、 Data is separated from use cases 、 Component technology 、 A unified platform for long-term construction from multiple dimensions .

We all know , Testing cannot be completely exhaustive , But we can adopt different regression testing strategies at different stages of the software , Reduce or even avoid serious escape defects in production . Of course , If we start from the whole life cycle of software production and strictly carry out code and defect management, we can more directly reduce the risk of online defects , After all, regression testing can also be used for unit testing .

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