White Box Testing

• A method of testing Application’s internal structure i.e. program code.

• It is a process of  giving input to the application code and checking how it processes the input and generates output.
• It is done by checking each line of the program code.
• It ensures testing of the implemented code.
• Also called as Clear Box testing, Open Box testing, Structural testing, Transparent Box testing, Code-Based testing, and Glass Box testing.
• The term "white box" was used because of the see-through box concept. The clear box or white box name symbolizes the ability to see through the software's outer shell (or "box") into its inner workings.
• Mainly applicable to lower levels of testing such as integration and unit levels.
• One of the basic goals of white box testing is to verify a working flow for an application.
• Generally done by software developers.

EXAMPLE: 
The tester chooses input to verifying loops, control flows, return types etc. through the code and determines the suitable outputs.

Advantages:

• Logical mistakes in the code can be located quickly.
• It helps in removing extra lines of code, which can bring in hidden defects.

Disadvantages:

• Quite complex and expensive.
• In-depth knowledge about the programming language is necessary. 
• It is time-consuming.