Topic: incremental testing VS. thread testing

According to Guide to CSTE Common Body of Knowledge, incremental testing refers to 'a disciplined method of testing the interfaces between unit-tested programs as well as between system component'. There are two types: Top-down and Bottom up.

Thread testing 'demonstrates key functional capabilities by testing a string of units that accomplish a specific function in the application'. Thread testing and incremental testing are usually utilized together.

Are they black-box testing or white-box testing? when should the testers perform this kind of testing? and how to use these techniques in practical project?

plz tell me with example.

Black Box Testing is testing without knowledge of the internal workings of the item being tested.  For example, when black box testing is applied to software engineering, the tester would only know the "legal" inputs and what the expected outputs should be, but not how the program actually arrives at those outputs.  It is because of this that black box testing can be considered testing with respect to the specifications, no other knowledge of the program is necessary.  For this reason, the tester and the programmer can be independent of one another, avoiding programmer bias toward his own work.

In this technique, we do not use the code to determine a test suite; rather, knowing the problem that we're trying to solve, we come up with four types of test data:

1. Easy-to-compute data
2. Typical data
3. Boundary / extreme data
4. Bogus data

For example, suppose we are testing a function that uses the quadratic formula to determine the two roots of a second-degree polynomial ax²+bx+c. For simplicity, assume that we are going to work only with real numbers, and print an error message if it turns out that the two roots are complex numbers (numbers involving the square root of a negative number).

We can come up with test data for each of the four cases, based on values of the polynomial's discriminant (b²-4ac):

Easy data (discriminant is a perfect square):

a	b	c	Roots
1	2	1	-1, -1
1	3	2	-1, -2

 

Typical data (discriminant is positive):

a	b	c	Roots
1	4	1	-3.73205, -0.267949
2	4	1	-1.70711, -0.292893

 

Boundary / extreme data (discriminant is zero):

a	b	c	Roots
2	-4	2	1, 1
2	-8	8	2, 2

 

Bogus data (discriminant is negative, or a is zero):

a	b	c	Roots
1	1	1	square root of negative number
0	1	1	division by zero

 

As with glass-box testing, you should test your code with each set of test data. If the answers match, then your code passes the black-box test.