Review brief

Beginner15 min

A warehouse service evaluates each SKU after inventory changes and opens or closes one low-stock alert. Product operations supplied an explicit threshold policy, and repeated evaluations must not create duplicate alerts.

Behavioral contract

Available inventory is onHand minus reserved; the caller guarantees both values are non-negative and reserved never exceeds onHand.
An enabled SKU is low when available inventory is less than or equal to reorderPoint and is healthy only when available is greater than reorderPoint.
Disabled SKUs never open an alert, and an existing alert for a disabled SKU is closed.
Evaluation opens or closes only when the persisted alert state needs to transition; evaluating an unchanged state performs no write.

Review instructions

1Review the evaluator against the stated transition table.
2Explain the inventory state that triggers each finding.
3Prioritize no more than three findings.

Learning objectives

• Derive decisions from the correct inventory quantity
• Check inclusive threshold boundaries
• Apply eligibility rules before state transitions

src/low-stock-evaluator.tsTypeScript

@@ -0,0 +1,29 @@

1+export interface InventoryItem {

2+ sku: string;

3+ enabled: boolean;

4+ onHand: number;

5+ reserved: number;

6+ reorderPoint: number;

7+ lowAlertOpen: boolean;

8+}

10+export interface LowStockAlerts {

11+ open(sku: string): Promise<void>;

12+ close(sku: string): Promise<void>;

13+}

14+

15+export async function evaluateLowStock(

16+ item: InventoryItem,

17+ alerts: LowStockAlerts,

18+): Promise<void> {

19+ if (item.onHand < item.reorderPoint) {

20+ if (!item.lowAlertOpen) {

21+ await alerts.open(item.sku);

22+ }

23+ return;

24+ }

25+

26+ if (item.lowAlertOpen) {

27+ await alerts.close(item.sku);

28+ }

29+}

Reference solution

The findings below are ordered by priority.

Findings

1. Reserved units are counted as available stock

Location: src/low-stock-evaluator.ts:19-27

Both branches decide from onHand alone. A SKU can therefore appear healthy even when reservations leave little or no stock available, and an existing alert can be closed while the available quantity is still low.

Calculate onHand - reserved once and use that value for both opening and closing decisions.

2. The reorder point itself is treated as healthy

Location: src/low-stock-evaluator.ts:19

The strict < comparison excludes an available quantity exactly equal to reorderPoint. The policy defines that boundary as low, so the evaluator fails to open an alert there or incorrectly closes an existing one.

Use an inclusive low-stock comparison and reserve the healthy branch for values strictly above the point.

3. Disabled SKUs can open alerts and keep them open

Location: src/low-stock-evaluator.ts:19-28

enabled is never checked. A disabled low SKU can open a new alert, while whether an existing alert closes depends on its quantity rather than the required disabled-state transition.

Handle disabled items first: close an open alert and otherwise perform no write.

Reasonable non-findings

The nested checks correctly avoid writes when the alert state already matches the selected branch.
Awaiting the alert repository operation before returning is appropriate.
Input-range validation belongs to the caller under the stated guarantees.