ITPEC FE Morning October 2021 Question 48

Created from the external specifications — black box testing looks only at inputs and expected outputs, never at the code.

Black box test cases come from what the program should do, as the external (functional) specification states it: equivalence partitioning, boundary value analysis, cause-effect graphs and decision tables all work from the specification. White box test cases come from the program's internal structure, and their thoroughness is measured by coverage criteria: statement, branch (decision) and condition coverage.

Answer (c)

Why not others:

• •(a) — branch coverage requires every branch in the code to be taken, so it needs the code: white box.
• •(b) — condition coverage requires every condition inside the decisions to be both true and false: white box.
• •(d) — deriving test data from the program structure is the definition of white box testing.

Key rule: Where the test data comes from names the method: from the specification it is black box, from the code and its coverage it is white box.

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