fix: return wechat pay webhook validation failures

server/src/internal/domestic-payments/wechat/handleWeChatPayWebhook.ts

@@ -1,4 +1,5 @@
 import type { Context } from "hono";
+import { StatusCodes } from "http-status-codes";
 import type { HonoEnv } from "@/honoUtils/HonoEnv.js";
 import {
 	DomesticPaymentIntentService,
@@ -25,10 +26,22 @@ export function createWeChatPayWebhookHandler({
 	return async (c: Context<HonoEnv>) => {
 		const ctx = c.get("ctx");
 		const body = await c.req.text();
-		const notification = await adapter.parseNotification({
-			body,
-			headers: c.req.raw.headers,
-		});
+		let notification: Awaited<ReturnType<PaymentProcessorAdapter["parseNotification"]>>;
+
+		try {
+			notification = await adapter.parseNotification({
+				body,
+				headers: c.req.raw.headers,
+			});
+		} catch (error) {
+			return c.json(
+				{
+					code: "FAIL",
+					message: error instanceof Error ? error.message : String(error),
+				},
+				StatusCodes.BAD_REQUEST,
+			);
+		}
 
 		await intentService.processParsedNotification({
 			ctx,

server/tests/unit/domestic-payments/wechat-pay-webhook-handler.test.ts

@@ -92,4 +92,100 @@ describe("createWeChatPayWebhookHandler", () => {
 			notification,
 		});
 	});
+
+	test("returns a WeChat FAIL response with HTTP 400 when notification parsing fails", async () => {
+		const body = JSON.stringify({ id: "notify_bad" });
+		const adapter: PaymentProcessorAdapter = {
+			provider: DomesticPaymentProvider.WeChatPay,
+			createPayment: async () => {
+				throw new Error("createPayment is not used in this test");
+			},
+			queryPayment: async () => {
+				throw new Error("queryPayment is not used in this test");
+			},
+			closePayment: async () => {
+				throw new Error("closePayment is not used in this test");
+			},
+			parseNotification: mock(async () => {
+				throw new Error("Invalid WeChat notification signature");
+			}),
+		};
+		const processParsedNotification = mock(async () => {
+			throw new Error("processParsedNotification must not be called");
+		});
+		const app = new Hono<HonoEnv>();
+		app.use("*", async (c, next) => {
+			c.set("ctx", ctx as HonoEnv["Variables"]["ctx"]);
+			await next();
+		});
+		app.post(
+			"/webhooks/wechatpay",
+			createWeChatPayWebhookHandler({
+				adapter,
+				intentService: { processParsedNotification },
+			}),
+		);
+
+		const response = await app.request("/webhooks/wechatpay", {
+			method: "POST",
+			body,
+			headers: {
+				"Wechatpay-Signature": "bad_signature",
+			},
+		});
+
+		expect(response.status).toBe(400);
+		await expect(response.json()).resolves.toEqual({
+			code: "FAIL",
+			message: "Invalid WeChat notification signature",
+		});
+		expect(processParsedNotification).toHaveBeenCalledTimes(0);
+	});
+
+	test("returns a server error after a parsed notification hits a service failure", async () => {
+		const notification = {
+			providerEventId: "notify_123",
+			idempotencyKey: "wechatpay:notification:notify_123",
+			eventType: DomesticPaymentEventType.WebhookPaid,
+			providerOrderId: "dp_order_123",
+			providerTransactionId: "wx_txn_123",
+			status: DomesticPaymentIntentStatus.Paid,
+			paidAt: 1_774_001_860_000,
+			rawPayload: { id: "notify_123" },
+			parsedPayload: { out_trade_no: "dp_order_123" },
+		};
+		const adapter: PaymentProcessorAdapter = {
+			provider: DomesticPaymentProvider.WeChatPay,
+			createPayment: async () => {
+				throw new Error("createPayment is not used in this test");
+			},
+			queryPayment: async () => {
+				throw new Error("queryPayment is not used in this test");
+			},
+			closePayment: async () => {
+				throw new Error("closePayment is not used in this test");
+			},
+			parseNotification: mock(async () => notification),
+		};
+		const processParsedNotification = mock(async () => {
+			throw new Error("database unavailable");
+		});
+		const handler = createWeChatPayWebhookHandler({
+			adapter,
+			intentService: { processParsedNotification },
+		});
+		const app = new Hono<HonoEnv>();
+		app.use("*", async (c, next) => {
+			c.set("ctx", ctx as HonoEnv["Variables"]["ctx"]);
+			await next();
+		});
+		app.post("/webhooks/wechatpay", handler);
+
+		const response = await app.request("/webhooks/wechatpay", {
+				method: "POST",
+				body: JSON.stringify({ id: "notify_123" }),
+		});
+
+		expect(response.status).toBe(500);
+	});
 });