feat: add AssetItem.purchaseOrderId (nullable FK)

tests/assets.test.ts

@@ -24,10 +24,42 @@ function postRequest(body: unknown): Request {
   });
 }
 
+// AssetItem.purchaseOrderId is a real FK to PurchaseOrder (see
+// schema.prisma / src/lib/assets.ts), and PurchaseOrder.vendorId is a real
+// FK to Vendor — tests that need a valid purchaseOrderId create real rows
+// first and use their ids. Mirrors tests/purchase-orders.test.ts's
+// createTestVendor() helper.
+function createTestVendor(overrides: { name?: string } = {}) {
+  return prisma.vendor.create({
+    data: {
+      name: overrides.name ?? "Test Vendor",
+      contactEmail: "[email protected]",
+      contactPhone: "0281234567",
+      address: "123 Test Street",
+    },
+  });
+}
+
+function createTestPurchaseOrder(overrides: { vendorId?: string } = {}) {
+  return prisma.purchaseOrder.create({
+    data: {
+      vendorId: overrides.vendorId as string,
+      orderDate: new Date("2026-08-01"),
+      expectedDate: new Date("2026-08-10"),
+    },
+  });
+}
+
 beforeEach(async () => {
-  // Each test starts from an empty table so listing/order assertions are
-  // deterministic.
+  // Each test starts from empty tables so listing/order assertions are
+  // deterministic. asset_items must be cleared before purchase_orders/
+  // vendors since asset_items has FKs (ON DELETE SET NULL to
+  // purchase_orders) — deleteMany order avoids relying on that cascade
+  // behavior in tests. purchase_orders must be cleared before vendors
+  // (ON DELETE RESTRICT to vendors, mirrors tests/purchase-orders.test.ts).
   await prisma.assetItem.deleteMany();
+  await prisma.purchaseOrder.deleteMany();
+  await prisma.vendor.deleteMany();
   // Default to a logged-in session — the tests below exercise business
   // logic, not auth gating (that's covered by the "auth gating" describe
   // block further down).
@@ -111,6 +143,69 @@ describe("POST /api/assets", () => {
     expect(body.error).toMatch(/warrantyEndDate/i);
   });
 
+  it("creates an asset item with a purchaseOrderId that references a real purchase order", async () => {
+    const vendor = await createTestVendor();
+    const purchaseOrder = await createTestPurchaseOrder({ vendorId: vendor.id });
+
+    const res = await POST(
+      postRequest({
+        serialNumber: "SN-007",
+        model: "Dell Latitude 5440",
+        purchaseDate: "2026-01-15",
+        purchaseOrderId: purchaseOrder.id,
+      })
+    );
+
+    expect(res.status).toBe(201);
+    const body = await res.json();
+    expect(body.purchase_order_id).toBe(purchaseOrder.id);
+  });
+
+  it("creates an asset item with no purchaseOrderId (stays null)", async () => {
+    const res = await POST(
+      postRequest({ serialNumber: "SN-008", model: "Dell Latitude 5440", purchaseDate: "2026-01-15" })
+    );
+
+    expect(res.status).toBe(201);
+    const body = await res.json();
+    expect(body.purchase_order_id).toBeNull();
+  });
+
+  it("rejects a purchaseOrderId that is a well-formed UUID but doesn't reference an existing purchase order", async () => {
+    const res = await POST(
+      postRequest({
+        serialNumber: "SN-009",
+        model: "Dell Latitude 5440",
+        purchaseDate: "2026-01-15",
+        purchaseOrderId: "00000000-0000-0000-0000-000000000000",
+      })
+    );
+
+    expect(res.status).toBe(400);
+    const body = await res.json();
+    expect(body.error).toMatch(/purchaseOrderId/i);
+    expect(body.error).toMatch(/does not reference an existing purchase order/i);
+
+    // And it must not have created anything.
+    const remaining = await prisma.assetItem.findMany();
+    expect(remaining).toHaveLength(0);
+  });
+
+  it("rejects a purchaseOrderId that is not a valid UUID", async () => {
+    const res = await POST(
+      postRequest({
+        serialNumber: "SN-012",
+        model: "Dell Latitude 5440",
+        purchaseDate: "2026-01-15",
+        purchaseOrderId: "not-a-uuid",
+      })
+    );
+
+    expect(res.status).toBe(400);
+    const body = await res.json();
+    expect(body.error).toMatch(/purchaseOrderId/i);
+  });
+
   it("rejects a duplicate serialNumber", async () => {
     await POST(postRequest({ serialNumber: "SN-006", model: "Dell", purchaseDate: "2026-01-15" }));
     const res = await POST(postRequest({ serialNumber: "SN-006", model: "HP", purchaseDate: "2026-02-01" }));