White Box Testing

So What is White Box Testing ?

White Box Testing is the testing of a software solution's internal coding and infrastructure.It focuses primarily on strengthening security, the flow of inputs and outputs through the application, and improving design and usability.White box testing is also known as clear, open, structural, and glass box testing.
it is one of two parts of the "box testing" approach of software testing. Its counter-part, blackbox testing, involves testing from an external or end-user type perspective. On the other hand, Whitebox testing is based on the inner workings of an application and revolves around internal testing. The term "whitebox" was used because of the see-through box concept. The clear box or whitebox name symbolizes the ability to see through the software's outer shell (or "box") into its inner workings.

White box testing involves the testing of the software code for the following:

• Internal security holes
• Broken or poorly structured paths in the coding processes
• The flow of specific inputs through the code
• Expected output
• The functionality of conditional loops
• Testing of each statement, object and function on an individual basis

White Box Testing Techniques

A major White box testing technique is Code Coverage analysis. Code Coverage analysis, eliminates gaps in a test case suite.It identifies areas of a program that are not exercised by a set of test cases.Once gaps are identified, you create test cases to verify untested parts of code, thereby increase the quality of the software product

statement Coverage  This technique requires every possible statement in the code to be tested at least once during the testing process.  Branch Coverage - This technique checks every possible path (if-else and other conditional loops) of a software application. Tools: An example of a tool that handles branch coverage testing for C, C++ and Java applications is TCAT-PATH

Apart from above, there are numerous coverage types such as Condition Coverage, Multiple Condition Coverage, Path Coverage, Function Coverage etc.Each technique has its own merits and attempts to test (cover) all parts of software code.

Using Statement and Branch coverage you generally attain 80-90% code coverage which is sufficient.  

Types of White Box Testing

Unit Testing : It is often the first type of testing done on an application. Unit testing is performed on each unit or block of code as it is developed.

 Unit testing is essentially done by the programmer. As a software developer, you develop a few lines of code, a single function or an object and test it to make sure it works before continuing

Unit testing helps identify majority of bugs, early in the software development lifecycle. Bugs identified in this stage are cheaper and easy to fix.

Testing for Memory Leaks : Memory leaks are leading causes of slower running applications. A QA specialist who is experienced at detecting memory leaks is essential in cases where you have a slow running software application.

There are many tools available to assist developers/testers with memory leak testing , example , Rational Purify  for windows application

Apart from above a few testing types are part of both black box and white box testing. They are listed as below -

White Box Penetration Testing: In this testing, the tester/developer has full information of the application's source code, detailed network information, IP addresses involved and all server information the application runs on.  The aim is to attack the code from several angles to expose security threats

White Box Mutation Testing: Mutation testing is often used to discover the best coding techniques to use for expanding a software solution .