White box testing, Unit testing, and Component testing are different types of testing that do not only differ in the way we perform them but also differ in their end goal and objective. Especially it is not fair to compare unit or component testing with white box testing but people use these terms interchangeably hence it is important to understand the difference. The Unit-testing and component testing are testing levels whereas white-box is the testing type.
Testing level v/s Testing type
Before moving forward, it is important to understand the difference between a test level and the test type.
Software Test levels are the stages of testing like Unit testing, Component testing, Integration Testing, System Testing, and User Acceptance testing a software goes through till it reaches the end-user.
Whereas software testing types are different ways we can test software. Examples of testing types are black box, white box, grey-box testing types. In general, a tester performs different types of testing within the same testing level. A testing level can have white-box and/or black-box and/or grey-box software testing types implemented to thoroughly test the system
For eg, In the unit or component testing level, a developer can have a plan to perform white-box testing to improve the coding structure and can also perform black-box functional testing to check the functionality at each module level. Hence a unit or component testing can be a white box testing or black box or grey box depending on how are we are performing the testing.
Learn in detail - Software Testing Levels v/s Software Testing Types
White Box testing vs Unit Testing vs Component Testing
Below will help to understand the difference -
Learn - Types of White Box testing