In the Cleanroom development approach, which activity is considered the…
2026
In the Cleanroom development approach, which activity is considered the PRIMARY source of software correctness?
- A.
Executing statistical tests early in the development cycle
- B.
Using automated debugging tools to eliminate defects during coding
- C.
Rewriting modules until the defect rate becomes statistically negligible
- D.
Performing incremental functional verification without execution
Attempted by 1 students.
Show answer & explanation
Correct answer: D
Concept
Cleanroom Software Engineering (Harlan Mills, IBM) is built on one core principle: correctness is established through mathematically based, team-performed verification of each increment against its formal specification, carried out BEFORE the code is ever executed. Execution-based testing is a separate, later activity run by an independent certification team to estimate reliability, not to establish correctness.
Application
Each increment of the system is specified formally (box-structure / state-based specifications) before coding begins.
As the development team writes an increment, they subject it to structured, team-based correctness verification: a rigorous walkthrough/proof argument checking the code against its specification.
This verification step happens incrementally, piece by piece, and entirely through reasoning about the code — the team does not run or debug the increment themselves.
Only after this non-execution-based verification is complete does the increment pass to an independent test team, which performs statistical usage testing (executing the software under a modeled usage profile) to certify reliability — a separate activity from establishing correctness.
Cross-check
Activity | Role in the Cleanroom process |
|---|---|
Statistical testing | Performed later by an independent team on already-verified code, to estimate reliability — not to establish correctness |
Automated debugging during coding | Not performed by the development team in Cleanroom; increments are not executed/debugged by their authors |
Rewriting until the defect rate is negligible | Not a Cleanroom activity; correctness is verified up front rather than reached by iterative execution and patching |
Incremental functional verification without execution | The team-based, specification-driven proof activity performed on every increment — this is where correctness is established |
Result: the activity that is the primary source of software correctness in Cleanroom is performing incremental functional verification without execution.