What Is Mutation Testing?

Mutation Testing is where certain statements in the source code are changed. Furthermore, it is a type of White Box Testing, which is mainly used for Unit Testing.

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Defining Mutation Testing

Mutation testing is used in designing new software tests, and likewise, t evaluate the quality of existing software tests. Hence, it also involves modifying a program in small ways. In addition to this, tests detect and likewise reject mutants. Therefore, by causing the behavior of the original version to differ from the mutant.

It makes small modifications to source code called mutants. Hence, to detect errors or defects in the system or program under test. its primary goal is to terminate mutants. As many mutants as needed may be set up by the testers. They must see to it that every mutant remains different and is also unique from the original system. Mutation testing is an excellent unit test suite typically detects the program mutations and fails automatically.

Explaining Mutation Testing

The level or intensity of mutation applied to a given code block may vary. A typical mutation testing implementation involves replacing a logical operator with its inverse. Multiple mutation testing levels may result in compilation errors.

The mutated code may fail or pass the unit test. Hence, it depends on the quality of the testing process. Mutated code errors need to be detected. Otherwise, it will result in failure. Rewriting the code may be necessary if the unit test fails to identify errors. 

Advantages of Mutation Testing

  • Program code fault identification
  • Effective test case development
  • Detection of loopholes in test data
  • Improved software program quality
  • Elimination of code ambiguity

Disadvantages of Mutation Testing

  • Difficult implementation of complex mutations
  • Expensive and time-consuming
  • Requires skilled testers with programming knowledge

Mutation Testing Process

  1. Create mutant software – introduces semantic changes to the Java byte code. For instance, inverting the logic of if and while statements. And also eliminating function calls. 
  2. Prepare test cases to the original and likewise, mutant software
  3. Execute the original and also the mutant programs. When the outcome of the original and mutant program is similar, than the mutant is terminated. 
  4. Compute mutation score: Mutation score refers to the percentage of killed mutants with total added mutants. Mutation score=(Killed mutants/Total mutants)*100. The mutation test score is directly proportional to the success of the test cases or test suite.

In Conclusion

The purpose of mutation testing is for evaluating test case effectiveness. Furthermore, to detect errors in the event of modification or changes in the program code. However, these changes are minimal so that it does not affect the overall quality of the application program. 

Furthermore, it is a time-consuming process. However, it is effective to detect loopholes and flaws in the programming code. Hence, instead of seeing it as a testing technique, mutation testing may be more seen as a test improvement methodology. Which improves the effectiveness and likewise, the quality of the test cases. Therefore, ensuring good test coverage and hence, subsequently the better test results.

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