Glass Box Testing or White Box Testing

This type of software testing involves examining the internal structure, design, implementation and working of the software program. During this test, a Tester use design test cases are with the help of programming skills and internal perspective of the system. He/ She then selects inputs to exercise paths through the code and determine the result.

White-Box Testing is applicable at the levels, be it Unit Testing level for testing paths within units, Integration Testing level for for testing paths between units, or System Level for testing paths between sub-systems.

Various techniques that are used in Glass box Testing are

• API Testing for applications using private and public APIs;
• Code Coverage for satisfying criteria of code coverage;
• Fault Injection for measuring the efficiency of testing strategies by creating faults;
• Mutation Testing for evaluating quality of existing test and designing new ones
• Static Testing for testing the sanity of software code, algorithm or document.

Even though White-Box Testing is a thorough process and can be initiated at the early stages, it is a highly complex testing approach and misses out the evaluation of functionality part of the software.