White Box Testing is a software testing strategy which verifies an application while its internal structure, design, and implementation details are available for the testers. It has got many names such as Clear Box Testing or Open Box Testing or Glass Box Testing or Transparent Box Testing or Code-Based Testing or Structural Testing.
In white box testing, the tester selects inputs to execute paths through the code and resolves the appropriate outputs. Programming skills and the implementation information are crucial. White box testing coverage goes beyond how the application looks or functions externally instead it more drills into the core of a system.
This method got called with such different names as any application, in the view of the testers, is similar to a white or a glass box. And they can also take a closer look inside the whole system.
White box Testing as per ISTQB
ISTQB represents the International Software Testing Qualifications Board. It is a non-profit Belgium based organization which contributes to global testing standards and provides testing certifications. Let’s hear how does ISTQB define the White box Testing?
White box Testing:
It is a testing methodology which gets executed based on the internal structure and the design of the software.
White box Test Design Process:
Test design and selection proceeds upon the details available of the internal code and design structure of the application under test.
White box Test Scenario:
A tester or a developer can also go through the implementation in the code of a specific feature in the application, resolves all positive and negative paths and verifies the outcomes as per the expected behavior, which gets also ascertained by analyzing the implementation at the code level.
We can assume the White Box Testing as the work of a mechanic who inspects the engine to detect why the vehicle is not operating.
White box Testing Applies to:
This method touches upon the following areas of manual testing:
1. Unit Testing:
Here, the smallest unit of the code determines the possible paths for the validation.
2. Integration Testing:
In this flow, the tester performs validation between two or more modules of the application.
3. System Testing:
This phase is the stability phase where the QA finds and examines the paths between different subsystems.
The main level of the white box testing works by focusing on multiple units present in the application.
White box Testing Techniques:
Following techniques help in writing white box test cases and in execution as well.
1. Memory leak detection:
Here, the testers focus on finding problems like the stack overflow, buffer overflows, memory leaks, etc. The tools such as Valgrind, C++ memory leak detector get used to supporting this level.
2. Code coverage:
Code coverage gets also measured to ensure the percentage of the code covered by the white box tests. This process can guide the testers to write cases for areas which remain untouched. Here, tools like C++ code coverage validator, GCOV facilitates this level.
This technique has three different levels.
i) Statement Coverage:
In programming terminology, a statement represents the line of code or the instruction for the compiler to recognize and respond accordingly.
It returns the total executable lines of the application exercised by the tests executed.
ii) Branch Coverage:
A branch indicates instructions that include the use of IF clause in the code.
An IF clause has two possible branches: Success and Failure.
It helps to determine the amount of code using the branching which further drives to write the appropriate no. of test cases.
ii) Path Coverage:
Path coverage is focussing on determining the tests covering all possible paths in an application.
It is an inclusive technique which makes sure that no paths remain left without validation. Such coverage is even more useful than the Branch coverage. This technique is beneficial for validating the complex products.
White box Testing Benefits:
1. The tester can begin white box testing at an earlier stage. They don’t have to wait for the entire modules to become available.
2. This testing process is more inclusive, provides more coverage into application parts, and hence increases the possibility of testing most of the paths.
White box Testing Drawbacks:
1. White box test design is sophisticated, requires relevant programming skills, and the resources who have a thorough knowledge of the application design.
2. Managing the test code and the scripts are additional tasks and require extra efforts.
3. This type of testing has tight coupling with the source of the application under test. Hence, frequent changes in the code require re-execution, and even sometimes lead to new paths for the testing.
Don’t miss to read our submission of top 100 manual testing interview questions. It is helpful for the testers of all experience levels to crack any testing interview.