Stop incomplete quote requests reaching the calculator
The batch caller sometimes omits the pricing revision and the web caller sends quantity as text. Both currently reach calculation through a partially populated options object.
- Focused work estimate
- 1h 30m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Input validation · API design · Type modeling
Estimated field mix
- Backend60%
- API design40%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
Pattern topics
- BuilderCompare
Assess whether staged construction adds value for quote inputs, or a validated immutable constructor provides the same guarantees more clearly.
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Project context
A fictional equipment-rental service supports direct customers and two reseller contracts. Pricing now lives in a long conditional with subclasses left over from a discontinued campaign. Build a local TypeScript quoting module and synthetic fixtures; no starter repository, real charges, tax advice, or payment connection is supplied. Amounts use integer cents and the exercise supports USD only.
Setup prerequisites
- Pure functions
- Object composition
- Integer arithmetic
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- A quote request requires tenant, contract revision, nonempty product identity, positive integer quantity, and a nonnegative integer unit price.
- Construction fails with field-level errors before any pricing rule runs.
- Compare a staged Builder with a validated constructor or factory; select the smallest interface that cannot expose an incomplete request.
Implementation constraints
- Do not silently fill the contract revision from a mutable global default; runtime input validation remains necessary with TypeScript.
Verification to include
- Construct equivalent valid requests from the synthetic batch and web inputs.
- Reject missing revision, quantity 'ten', and quantity zero while asserting the calculator was not called.
Deliverables
- Validated request construction API and invalid-input fixtures
Rollout and recovery
Route the two local callers through validation together; keep error mapping compatible with their declared response contracts.
Value of the work
For the engineer: Practice choosing, testing, and removing object-design abstractions around versioned business rules and tenant isolation.
For the team: Review changes that let a team introduce a contract without silently changing existing quotes, together with the maintenance costs of the chosen design.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.