What are different types of white box testing? Part 2

White-box testing or clear box testing, transparent box testing, glass box testing, structural testing as it is also known can be defined as a method for testing software applications or programs. White box testing includes techniques that are used to test the program or algorithmic structures and working of that particular software application in opposition to its functionalities or the results of its black box tests.

White-box testing can be defined as a methodology to verify the source code of the software system if it works as expected or not. White box testing is a synonym for structural testing.

Unit testing and Integration testing is already discussed in previous post.

Types of White Box Testing

- Function level testing:
This white box testing is carried to check the flow of control of the program. Adequate test cases are designed to check the control flow and coverage. During functionality level white box testing simple input values can be used.

- Acceptance level testing:
This type of white box testing is performed to determine whether all he specifications of a software system have been fulfilled or not. It involves various kinds of other tests like physical tests, chemical tests and performance tests.

- Regression level testing:
This type of white box testing can also be called as retesting. It is done after all the modifications have been done to the software and hardware units. Regression level white box testing ensures that the modifications have not altered the working of the software and has not given rise to more bugs and errors.

- Beta level testing:
Beta testing is that phase of software testing in which a selected audience tries out the finished software application or the product. It is also called pre- release testing.

What are different types of white box testing? Part 1

White-box testing or clear box testing, transparent box testing, glass box testing, structural testing as it is also known can be defined as a method for testing software applications or programs. White box testing includes techniques that are used to test the program or algorithmic structures and working of that particular software application in opposition to its functionalities or the results of its black box tests.

White-box testing can be defined as a methodology to verify the source code of the software system if it works as expected or not. White box testing is a synonym for structural testing.

There are certain levels only at which white box testing can be applied. The levels have been given below in the list:
- Unit level
- Integration level and
- System level
- Acceptance level
- Regression level
- Beta level

Unit level testing:

This type of white box testing is used for testing the individual units or modules of the software system. Sometimes it also tests a group of modules. A unit is the smallest part of a program and cannot be divided further into smaller parts. Units form the basic structure of a software system. Unit level white box testing is performed to check whether or not the unit is working as expected. White box testing is done to ensure whether the unit is working properly or not so that later it can be integrated with the other units of the system. It is important to test units at this level because later after integration it becomes difficult to find errors. The software engineer who has written the code only knows where the potential bugs can be found. Others cannot track them. Therefore, such kinds of flaws are completely in the privacy of the writer. Unit level white box testing can find up to 65 percent of the total flaws.

- Integration level testing:
In this type of white box testing the software components and the hardware components are integrated and the program is executed. This is done mainly to determine whether both of the software units and hardware units are working together in harmony. It includes designing of test cases which check the user interfaces of the two components.

What is Black box testing and what are its advantages and disadvantages ?

Black box testing is a test design method. It treats the system as a "black-box" so it does not explicitly use the knowledge of the internal structure. In other words, the test engineer does not require to know the internal working of the black box. Black box testing focuses on the functionality part of the module. Black box testing is also known as opaque box and closed box testing. While the term black box testing is more commonly, many people prefer the terms "behavioral" and "structural" for black-box and white-box respectively.
There are bugs that cannot be found using only black box testing or only white box testing. If the test cases are extensive and the test inputs are also from a large sample space then it is always possible to find majority of the bugs through black box testing.

The basic functional or regression testing tools capture the results of black box tests in a script format. Once captured, these scripts can be executed against future builds of an application to verify that new functionality has not disabled previous functionality.

Advantages of Black Box Testing
- It is not important for the tester to be technical. He can be a non-technical person.
- This testing is most likely to find those bugs as the user would have found.
- Testing helps to identify the vagueness and contradiction in functional specifications.
- Test cases can be designed as soon as the functional specifications are complete.

Disadvantages of Black Box Testing
- There are chances of repetition of tests that are already done by the programmer.
- The test inputs needs to be from large sample space.
- It is difficult to identify all possible inputs in limited testing time. So, writing test cases is slow and difficult.
- There are chances of having unidentified paths during testing.

What can be white box testing used for, tools used for white box testing.

White box testing (WBT) is also called Structural or Glass box testing. It deals with the internal logic and structure of the code. A software engineer can design test cases that exercise independent paths within a module or unit, exercise logical decisions on both their true and false side, execute loops at their boundaries and within their operational bounds and exercise internal data structures to ensure their validity. White Box testing can be used for :
- looking into the internal structures of a program.
- test the detailed design specifications prior to writing actual code using the static analysis techniques.
- organizing unit and integration test processes.
- testing the program source code using static analysis and dynamic analysis techniques.

Tools used for White Box testing:
- Provide run-time error and memory leak detection.
- Record the exact amount of time the application spends in any given block of code for the purpose of finding inefficient code bottlenecks.
- Pinpoint areas of the application that have and have not been executed.

The first step in white box testing is to comprehend and analyze available design documentation, source code, and other relevant development artifacts, so knowing what makes software secure is a fundamental requirement. Second, to create tests that exploit software, a tester must think like an attacker. Third, to perform testing effectively.

Testing Approaches: Functional Testing versus Structural Testing and Mutation testing

In functional testing, functionality of the module is tested and structure is not considered. Test cases based on specifications and internals of modules are not considered. This type of testing is also known as black box testing. The objective here is to ensure that `correct results'' are obtained when `good inputs'' are applied to the various parts of the design, and when `bad inputs'' are applied the design operates in a predictable manner. Functional testing can therefore be considered as concentrating on checking that the data paths operate correctly.

Structural testing is used to test the implementation of the program. Structural testing, also known as white box or open box testing, is normally applied to sequential HDL code and concentrates on checking that all executable statements within each module. Structural testing involves :
- Statement coverage : This ensures that each and every statement is tested. Software tools called profilers are used to carry this statement coverage.
- Branch coverage : Each and every condition is taken, and inputs are given in such a way that each branch is executed at least once.
- Path Coverage : To test loops, this is required. For example the statement
for(i=o;i<=100;i++) is executed 101 times.

Mutation testing is required to ensure that the software does not fail. It is a good debugging mechanism. The program is modified slightly to obtain mutants of the program. Different mutants are tested with the same test cases. If the mutant fails, and the actual program works correctly, confidence is gained in the program and test cases are considered good. To produce mutants, mutation operators are defined.
- Constant replacement
- Variable replacement
- Arithmetic operator replacement
- Relational operator replacement
- Goto label replacement