Should black box or white box testing be the emphasis for testers?

Question

Which type of testing would you say should be the emphasis (for testers/QAs), and why?

A quick set of definitions from wikipedia:

Black box testing

Answer 1

• Black box testing should be the emphasis for testers/QA.
• White box testing should be the emphasis for developers (i.e. unit tests).
• The other folks who answered this question seemed to have interpreted the question as Which is more important, white box testing or black box testing. I, too, believe that they are both important but you might want to check out this IEEE article which claims that white box testing is more important.

Answer 2

Black Box Testing is a software testing method in which the internal structure/ design/ implementation of the item being tested is NOT known to the tester. White Box Testing is a software testing method in which the internal structure/ design/ implementation of the item being tested is known to the tester.

Answer 3

I only partially agree with the top rated answer for this question. Which type of testing would you say should be the emphasis (for testers/QAs), and why?

1. I agree that: "Black box testing should be the emphasis for testers/QA."
2. I agree that White box testing should be the emphasis for developers, but I don't agree that White Box testing is just unit tests.

I agree with the definition here which states that White Box Testing method is applicable to the following levels of software testing:

• Unit Testing: For testing paths within a unit
• Integration Testing:For testing paths between units
• System Testing: For testing paths between subsystems

Answer 4

• Black box testing you dont see the system under test inner workings.
• White box testing you have full view into the system under test. Here are a few pictures showing this.

Testers need to focus on the testing pyramid. You will want to understand unit tests, integration tests, and end to end tests. Each of these can be performed both with black box and white box testing. Start small and work your way up learning the different types and when to use each. remember you cant always test everything.

Answer 5

QA should focus on Black box testing. The main goal of QA is to test what the system does (do features meet requirements ?), not how it does it.

Anyway it should be hard for QA to do white box testing as most of QA guys aren't tech guys, so they usually test features through the UI (like users).

A step further, I think developpers too should focus on Black box testing. I disagree with this widespread association between Unit testing and White box testing but it may be just a question a vocabulary/scale. At the scale of a Unit test, the System Under Test is a class/method which has contract (through its signature) and the important point is to test what it does, not how. Moreover White box testing implies you know how the method will fill its contract, that seems incompatile with TDD to me.

IMHO if your SUT is so complex that you need to do white box testing, it's usually time for refactoring.

Answer 6

Black Box

1 Focuses on the functionality of the system Focuses on the structure (Program) of the system

2 Techniques used are :

· Equivalence partitioning

· Boundary-value analysis

· Error guessing

· Race conditions

· Cause-effect graphing

· Syntax testing

· State transition testing

· Graph matrix

Tester can be non technical

Helps to identify the vagueness and contradiction in functional specifications

White Box

Techniques used are:

· Basis Path Testing

· Flow Graph Notation

· Control Structure Testing

1. Condition Testing

2. Data Flow testing

· Loop Testing

1. Simple Loops

2. Nested Loops

3. Concatenated Loops

4. Unstructured Loops

   Tester should be technical

   Helps to identify the logical and coding issues.