G&W Chapter 22: Test Cases Software Specification Lecture 29 Prepared by Stephen M. Thebaut, Ph.D. University of Florida

Part V: Greatly Improving the Odds of Success Ambiguity Metrics Technical Reviews Measuring Satisfaction Test Cases Studying Existing Products Making Agreements Ending

Rationale Designing black-box test cases jointly with clients early in the requirements process is an extremely effective way to stimulate anticipation of product use (and therefore elicit requirements). stimulus response

Test Case Forms / Sources Stimulus-response pairs, as in: “If X happens, the product should do Y.” Input and output conditions Causes and Effects Scenarios / Use-Cases: threads of hypothetical product behavior Marketing brochures User manuals

Black-Box Coverage Strategies Equivalence Partitioning: sampling valid and invalid equivalence classes of stimuli (“inputs”). Boundary Value Analysis: exploring valid and invalid stimuli near constraint boundaries.

Black-Box Coverage Strategies (cont’d) Cause-Effect Analysis: systematic exploration of valid and invalid stimuli combinations. Intuition and Experience: explore unexpected or unusual product use or environmental scenarios.

G&W’s Black-Box Testing Process Construct test cases by imagining that the product has been built and asking “What if” questions. Answer the test cases, and discuss with stakeholders to obtain agreement. Attempting to reach agreement will generally lead to new “What if” questions. Add these to the list, answer them, and repeat the process until the list stabilizes.

G&W’s Black-Box Testing Process (cont'd) Review the list with a team of designers and professional writers to identify over-constrained replies; revise to give the greatest possible design freedom – but no more. Document the cases so they will become the starting basis for system and acceptance tests.

Automatic Test Case Synthesis? Could test cases (e.g., scenarios – threads of hypothetical product behavior) be generated automatically / semi-automatically during the early stages of RE to stimulate anticipation?

Automatic Test Case Synthesis? (cont’d) One approach: model fragmentary, incomplete (and possibly conflicting) requirements in a rule-base and use a forward-chaining execution engine to generate scenarios of product behavior. (Marcel: Thebaut/ Interrante,1991)

G&W Chapter 22: Test Cases Software Specification Lecture 29 Prepared by Stephen M. Thebaut, Ph.D. University of Florida