Difference between unit, black box or white box testing?

Question

What is the difference between unit, black box & white box testing? Is there any similarity between black box & unit testing?

Answer 1

• A unit test would test an individual part of something larger, in programming this could be a single method in a class used by a program.
• White box testing is where the tester has knowledge of the system they are testing and uses this to decide what to test. For example, knowing a number is parsed from a textbox the tester might give a value too large for the data they field will be stored as.
• Black box testing is here the tester doesn't have knowledge of the system, i.e. they see what they are testing as a black box where things go in (inputs/data etc.) and things come out (printouts/information etc.), they don't know how things work inside the box. All the tester cares about is did they get the right output for the input they tested.

Answer 2

The term unit test describes the subject of the test, usually a module or another particular unit of code. The terms white box test and black box test describe the knowledge of the tester about the inner workings of the subject.