feat: Wabenhain Honig-Shop Anwendung

Vollstaendige Next.js/Prisma-E-Commerce-Anwendung fuer eine Imkerei:
Shop, Warenkorb, Stripe-Checkout, Kundenkonto mit 2FA, Admin-Bereich
(Produkte, Ernten, Chargen, Bestellungen, Gutscheine, admin-editierbare
Website-Inhalte), i18n (DE/EN), Rate-Limiting/CSP/Audit-Log-Haertung,
PostgreSQL- und MySQL-Unterstuetzung ueber austauschbare Prisma-
Treiber-Adapter, Unit-/Komponenten-/E2E-Tests.

src/lib/bulk-discount-calc.test.ts

@@ -0,0 +1,48 @@
+import { describe, test, expect } from "vitest";
+import { resolveBulkDiscount, getNextBulkDiscountTier } from "./bulk-discount-calc";
+
+const tiers = [
+  { code: "MENGE10", minQuantity: 3, percent: 10 },
+  { code: "MENGE15", minQuantity: 6, percent: 15 },
+];
+
+describe("resolveBulkDiscount", () => {
+  test("returns null when no tier is configured", () => {
+    expect(resolveBulkDiscount([], 5)).toBeNull();
+  });
+
+  test("returns null below the lowest threshold", () => {
+    expect(resolveBulkDiscount(tiers, 2)).toBeNull();
+  });
+
+  test("picks the lowest tier at its boundary", () => {
+    expect(resolveBulkDiscount(tiers, 3)).toEqual({ code: "MENGE10", minQuantity: 3, percent: 10 });
+  });
+
+  test("picks the higher tier once its threshold is reached", () => {
+    expect(resolveBulkDiscount(tiers, 6)).toEqual({ code: "MENGE15", minQuantity: 6, percent: 15 });
+  });
+
+  test("is unaffected by tier input order", () => {
+    const shuffled = [...tiers].reverse();
+    expect(resolveBulkDiscount(shuffled, 6)).toEqual({ code: "MENGE15", minQuantity: 6, percent: 15 });
+  });
+});
+
+describe("getNextBulkDiscountTier", () => {
+  test("returns null when no tier is configured", () => {
+    expect(getNextBulkDiscountTier([], 1)).toBeNull();
+  });
+
+  test("returns null once the highest tier is reached", () => {
+    expect(getNextBulkDiscountTier(tiers, 6)).toBeNull();
+  });
+
+  test("reports units and percent of the next tier", () => {
+    expect(getNextBulkDiscountTier(tiers, 1)).toEqual({ unitsUntilNext: 2, percent: 10 });
+  });
+
+  test("reports the tier after the currently active one", () => {
+    expect(getNextBulkDiscountTier(tiers, 3)).toEqual({ unitsUntilNext: 3, percent: 15 });
+  });
+});