• Requirement/risk is ready and team needs executable test cases.
• Test coverage must be explicit before development freeze.
• Multiple testers need consistent case quality standard.

• Produce complete, reviewable, and executable test cases and include reusable parameterized case patterns.
• Cover main flow, edge flow, negative flow, and data variation.
• Ensure each case has clear precondition, action, and expected result.

1. Derive scenarios from business rule and user journey.
2. Split scenarios into atomic test objectives.
3. Define data set and environment prerequisites per case.
4. Write steps with observable checkpoints.
5. Add expected outcomes with verification source.
6. Run self-review for ambiguity, duplication, and missing boundaries.

Input:

• Story: apply coupon during checkout, with member/non-member variants

Output:

• Cases for valid coupon, expired coupon, overlap rule, rollback on payment failure
• Explicit expected totals and error messages
• Traceability to requirement clauses

Input:

• "Write checkout test cases"

Output (problem):

• High-level bullet list only, no steps, no data, no expected results
• Not executable by another tester

• Do not produce narrative-only pseudo cases.
• Do not skip failure-path validation.
• Do not mix multiple objectives into one case.
• Do not omit test data and preconditions.
• Do not claim coverage completeness without traceability.