White Box Testing | White Box Testing in Software Engineering

White box testing is a testing technique which evaluates the code and the internal structure of software. It is the detailed investigation of internal logic and structure of the code. White-Box Testing is the testing of a software solution's inner coding and infrastructure.

Open-box testing is a software evaluating method used to examine the internal structure, design, coding and inner-working of software. Developers use this testing method to verify the flow of inputs and outputs through the application, improving usability and design and strengthening security.

In order to perform white-box testing on an application, a tester needs to know the internal workings of the code. White box testing involves testing the product's underlying structure, architecture, and code to validate input-output flow and enhance design, usability, and security.

The white box test method is the one that looks at the code and structure of the product to be tested and uses that knowledge to perform the tests. Designing white box test cases require a thorough knowledge of the internal structure of a program, and therefore white box testing is also called structural testing.

The other name of white box testing is clear box testing because unlike black box testing the code is available and visible. A few of the other names given to white box testing are open box testing, transparent box testing, glass testing, and code-based testing. White box testing is called "open box" because the code is visible to the tester during the examination.

Types of White Box Testing:

 

White Box testing can be classified into any of the following types:

 

Mutation Testing: Mutation testing is a type of testing based on alterations or mutations. Minute modifications are made to the source code to see if the provided test cases can discover bugs in the code. Developers commonly use this testing to test the code that they have modified after detecting bugs or making corrections.

 

Unit Testing: Unit testing is performed on each unit or block of code as it is developed. The developer tests a few lines of code, a single function or an object for correct working.

Unit testing ensures that each component performs as intended. Bugs identified in this stage are cheaper and easy to fix. Unit testing is helpful as it identifies the majority of errors early in the development cycle, making them cheaper and easier to fix.

 

Integration Testing: This method is concerned with combining individual unit or components of the source code and testing them as a group. The purpose of this testing is to expose any errors in the interaction of different components together.

Integration testing is performed to check that modules/components operate as intended when combined, i.e. to ensure that modules that performed fine independently do not have difficulties when merged.

 

Penetration Testing: This method is used to check if errors from outside the system can affect it. This test involves attacking the code from all directions to expose security threats. It's concerned about the software's integration with external factors and errors from outside that can bring the system down. The aim is to attack the code from several angles to expose security threats.

 

Regression Testing: In regression testing, the tester performs further tests to verify that a recent change in the application’s code has not harmed existing functionalities. The already executed test cases are rerun to confirm that previously created and tested features are working as desired. It verifies that the old code still works even after fixing bugs, adding extra security features, or implementing any changes.

White Box Testing Techniques:

 

There are Different Types of White Box testing techniques available to use. Following are important White Box Testing Techniques:

• Statement Coverage
• Branch Coverage
• Path Coverage
• Decision Coverage
• Condition Coverage
• Multiple Condition Coverage
• Basis path Testing
• Loop testing

 

Statement Coverage: Statement coverage is the most basic form of code coverage analysis in white box software testing. This technique includes every possible statement in the code. In this technique, the tester tests every statement at least once, thereby assuring that all of the code is tested.

A statement   is a line of code or an instruction. Statement coverage ensures every single line of code is tested. This technique examines each line of code at least once. In this technique, the aim is to traverse all statements at least once. Hence, each line of code is tested. 

 

Branch Coverage: Branch coverage is a white box software testing technique that measures the number of branches of the control structures that have been executed. In branch coverage, we check if each branch is processed at least once. This technique is running a series of tests to ensure that all branches are tested at least once.

 

Branch coverage ensures every branch is tested. In this technique, test cases are designed so that each branch from all decision points is traversed at least once. Using this technique, each possible path or decision point of a software application is checked for accuracy.

 

Path Coverage- ensures all possible paths are tested. Path coverage examines all the paths in a given program. This is a thorough strategy that assures that all program paths are explored at least once. Path coverage is more effective than branch coverage. This technique corresponds to testing all possible paths which means that each statement and branch is covered.

 

Decision Coverage: This includes testing every possible decision condition and other conditional loops at least once. Decision Coverage is a white box testing methodology that reports the true or false results of each Boolean expression present in the source code.

Condition Coverage: This technique covers all individual conditions. In this technique, all individual conditions are checked. With condition coverage, all of the conditions in the program to be evaluate as both true and false at least once. The purpose of condition coverage is to examine the outcome of each logical condition.

Multiple Condition Coverage:   In this testing technique, all the different combinations of conditions for each decision are evaluated.

Basis Path Testing: Each independent path in the code is taken for testing. In this technique, control flow graphs are created from either code or flowchart. Cyclomatic complexity is then calculated to define the number of independent paths so that the minimal number of test cases can be designed for each independent path.

 

Loop Testing: The technique focuses on loops. Loops are commonly used in white box testing and are fundamental to many algorithms. Problems are often found at the beginning or the end of a loop. This technique checks the reliability of loops, and involves simple, nested and concatenated loops.