In the integration testing of firmware with 25 KLOC (25,000 lines), 30 defects were found. Based on the organization's past results, the guideline for defects found in this phase is 2 to 4 per KLOC. Which is the most appropriate evaluation of this result?

Answer: B. The defect density is 1.2 per KLOC, below the guideline, so rather than assuming the quality is good, check whether testing was insufficient (missing test cases)

The defect density is 30 defects ÷ 25 KLOC = 1.2 per KLOC, below the guideline of 2 to 4. When it is below the guideline, the code may indeed be well made, but defects may also have been missed because testing was insufficient, for example because the test cases do not cover the specification well enough or the test viewpoints are biased. Therefore the result is evaluated after analyzing the test coverage and the nature of the defects. When the density is above the guideline, the quality of the design and implementation is examined.

• A. At 1.2 per KLOC, it is outside the guideline of 2 to 4.
• B. Correct. When the density is below the guideline, insufficient testing is suspected and checked.
• C. The low count may be due to insufficient testing, so skipping tests without checking is dangerous.