Where may functional testing be performed?

Question

Options

• AAt system and acceptance testing levels only.
• BAt all test levels.
• CAt all levels above integration testing.
• DAt the acceptance testing level only.

• A
  9% (5)
• B
  70% (37)
• C
  6% (3)
• D
  15% (8)

Explanation

Functional testing - which verifies that software behaves according to its specified requirements - can be applied at every test level: unit, integration, system, and acceptance. Whether you're checking that a single function returns the correct output (unit) or that an entire deployed system meets business needs (acceptance), you're validating what the software does, making B correct.

Why the distractors are wrong:

• A is wrong because it arbitrarily excludes unit and integration testing, where functional checks are common.
• C is wrong for the same reason - it excludes unit testing, and "above integration" is not a real boundary in testing theory.
• D is the most restrictive and most wrong; acceptance testing is just one level where functional testing occurs.

Memory tip: Think of "functional" as the type of testing (does it work correctly?), not the level. Since you can ask "does this work correctly?" at any level of granularity, functional testing is always level-agnostic - contrast this with non-functional testing (performance, security), which also spans all levels, helping reinforce the pattern.

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