test: improve branch coverage for billing.ts and keys.ts

billing.ts branches: 78.66% → 82.66%
- isDocFastSubscription expanded product object (not just string)
- isDocFastSubscription error handling path
- getOrCreateProPrice: new product + price creation
- getOrCreateProPrice: existing product, no active prices

keys.ts:
- createProKey UPSERT ON CONFLICT path (DB-only key)
- downgradeByCustomer customer not found in cache or DB
- updateKeyEmail DB fallback not-found path
- updateEmailByCustomer DB fallback not-found path

14 new tests, all 743 passing.

src/__tests__/billing-branch-coverage.test.ts

@@ -0,0 +1,260 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import express from "express";
+import request from "supertest";
+
+// Mock Stripe before importing billing router
+vi.mock("stripe", () => {
+  const mockStripe = {
+    checkout: {
+      sessions: {
+        create: vi.fn(),
+        retrieve: vi.fn(),
+      },
+    },
+    webhooks: {
+      constructEvent: vi.fn(),
+    },
+    products: {
+      search: vi.fn(),
+      create: vi.fn(),
+    },
+    prices: {
+      list: vi.fn(),
+      create: vi.fn(),
+    },
+    subscriptions: {
+      retrieve: vi.fn(),
+    },
+  };
+  return { default: vi.fn(function() { return mockStripe; }), __mockStripe: mockStripe };
+});
+
+let app: express.Express;
+let mockStripe: any;
+
+beforeEach(async () => {
+  vi.clearAllMocks();
+  vi.resetModules();
+
+  process.env.STRIPE_SECRET_KEY = "sk_test_fake";
+  process.env.STRIPE_WEBHOOK_SECRET = "whsec_test_fake";
+
+  const stripeMod = await import("stripe");
+  mockStripe = (stripeMod as any).__mockStripe;
+
+  // Default: product search returns existing product+price
+  mockStripe.products.search.mockResolvedValue({ data: [{ id: "prod_TygeG8tQPtEAdE" }] });
+  mockStripe.prices.list.mockResolvedValue({ data: [{ id: "price_123" }] });
+
+  const { createProKey, findKeyByCustomerId, downgradeByCustomer, updateEmailByCustomer } = await import("../services/keys.js");
+  vi.mocked(createProKey).mockResolvedValue({ key: "pro-key-123", tier: "pro", email: "test@test.com", createdAt: new Date().toISOString() } as any);
+  vi.mocked(findKeyByCustomerId).mockResolvedValue(null);
+  vi.mocked(downgradeByCustomer).mockResolvedValue(undefined as any);
+  vi.mocked(updateEmailByCustomer).mockResolvedValue(true as any);
+
+  const { billingRouter } = await import("../routes/billing.js");
+  app = express();
+  app.use("/v1/billing/webhook", express.raw({ type: "application/json" }));
+  app.use(express.json());
+  app.use("/v1/billing", billingRouter);
+});
+
+describe("Billing Branch Coverage", () => {
+  describe("isDocFastSubscription - expanded product object (lines 63-67)", () => {
+    it("should handle expanded product object instead of string", async () => {
+      // Test the branch where price.product is an expanded Stripe.Product object
+      mockStripe.webhooks.constructEvent.mockReturnValue({
+        type: "checkout.session.completed",
+        data: {
+          object: {
+            id: "cs_expanded_product",
+            customer: "cus_expanded",
+            customer_details: { email: "expanded@test.com" },
+          },
+        },
+      });
+
+      // Mock: line_items has price.product as an object (not a string)
+      mockStripe.checkout.sessions.retrieve.mockResolvedValue({
+        id: "cs_expanded_product",
+        line_items: {
+          data: [
+            { 
+              price: { 
+                product: { id: "prod_TygeG8tQPtEAdE" }  // Expanded object, not string
+              } 
+            }
+          ],
+        },
+      });
+
+      const { createProKey } = await import("../services/keys.js");
+      const res = await request(app)
+        .post("/v1/billing/webhook")
+        .set("content-type", "application/json")
+        .set("stripe-signature", "valid_sig")
+        .send(JSON.stringify({ type: "checkout.session.completed" }));
+
+      expect(res.status).toBe(200);
+      expect(createProKey).toHaveBeenCalledWith("expanded@test.com", "cus_expanded");
+    });
+
+    it("should handle expanded product object in subscription.deleted webhook", async () => {
+      mockStripe.webhooks.constructEvent.mockReturnValue({
+        type: "customer.subscription.deleted",
+        data: {
+          object: { id: "sub_expanded", customer: "cus_expanded_del" },
+        },
+      });
+
+      // subscription.retrieve returns expanded product object
+      mockStripe.subscriptions.retrieve.mockResolvedValue({
+        items: { 
+          data: [
+            { 
+              price: { 
+                product: { id: "prod_TygeG8tQPtEAdE" }  // Expanded object
+              } 
+            }
+          ] 
+        },
+      });
+
+      const { downgradeByCustomer } = await import("../services/keys.js");
+      const res = await request(app)
+        .post("/v1/billing/webhook")
+        .set("content-type", "application/json")
+        .set("stripe-signature", "valid_sig")
+        .send(JSON.stringify({ type: "customer.subscription.deleted" }));
+
+      expect(res.status).toBe(200);
+      expect(downgradeByCustomer).toHaveBeenCalledWith("cus_expanded_del");
+    });
+  });
+
+  describe("isDocFastSubscription - error handling (lines 70-71)", () => {
+    it("should return false when subscriptions.retrieve throws an error", async () => {
+      mockStripe.webhooks.constructEvent.mockReturnValue({
+        type: "customer.subscription.deleted",
+        data: {
+          object: { id: "sub_error", customer: "cus_error" },
+        },
+      });
+
+      // Mock: subscriptions.retrieve throws an error
+      mockStripe.subscriptions.retrieve.mockRejectedValue(new Error("Stripe API error"));
+
+      const { downgradeByCustomer } = await import("../services/keys.js");
+      const res = await request(app)
+        .post("/v1/billing/webhook")
+        .set("content-type", "application/json")
+        .set("stripe-signature", "valid_sig")
+        .send(JSON.stringify({ type: "customer.subscription.deleted" }));
+
+      // Should succeed but NOT downgrade (because isDocFastSubscription returns false on error)
+      expect(res.status).toBe(200);
+      expect(downgradeByCustomer).not.toHaveBeenCalled();
+    });
+
+    it("should return false when subscriptions.retrieve throws in subscription.updated", async () => {
+      mockStripe.webhooks.constructEvent.mockReturnValue({
+        type: "customer.subscription.updated",
+        data: {
+          object: { 
+            id: "sub_update_error", 
+            customer: "cus_update_error",
+            status: "canceled",
+            cancel_at_period_end: false,
+          },
+        },
+      });
+
+      mockStripe.subscriptions.retrieve.mockRejectedValue(new Error("Network timeout"));
+
+      const { downgradeByCustomer } = await import("../services/keys.js");
+      const res = await request(app)
+        .post("/v1/billing/webhook")
+        .set("content-type", "application/json")
+        .set("stripe-signature", "valid_sig")
+        .send(JSON.stringify({ type: "customer.subscription.updated" }));
+
+      expect(res.status).toBe(200);
+      expect(downgradeByCustomer).not.toHaveBeenCalled();
+    });
+  });
+
+  describe("getOrCreateProPrice - no existing product (lines 316-331)", () => {
+    it("should create new product and price when none exists", async () => {
+      // Mock: no existing product found
+      mockStripe.products.search.mockResolvedValue({ data: [] });
+      
+      // Mock: product.create returns new product
+      mockStripe.products.create.mockResolvedValue({ id: "prod_new_123" });
+      
+      // Mock: price.create returns new price
+      mockStripe.prices.create.mockResolvedValue({ id: "price_new_456" });
+
+      // Mock: checkout.sessions.create succeeds
+      mockStripe.checkout.sessions.create.mockResolvedValue({ 
+        id: "cs_new", 
+        url: "https://checkout.stripe.com/pay/cs_new" 
+      });
+
+      const res = await request(app)
+        .post("/v1/billing/checkout")
+        .send({});
+
+      expect(res.status).toBe(200);
+      expect(mockStripe.products.create).toHaveBeenCalledWith({
+        name: "DocFast Pro",
+        description: "5,000 PDFs / month via API. HTML, Markdown, and URL to PDF.",
+      });
+      expect(mockStripe.prices.create).toHaveBeenCalledWith({
+        product: "prod_new_123",
+        unit_amount: 900,
+        currency: "eur",
+        recurring: { interval: "month" },
+      });
+      expect(mockStripe.checkout.sessions.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          line_items: [{ price: "price_new_456", quantity: 1 }],
+        })
+      );
+    });
+
+    it("should create new price when product exists but has no active prices", async () => {
+      // Mock: product exists
+      mockStripe.products.search.mockResolvedValue({ data: [{ id: "prod_existing" }] });
+      
+      // Mock: no active prices found
+      mockStripe.prices.list.mockResolvedValue({ data: [] });
+      
+      // Mock: price.create returns new price
+      mockStripe.prices.create.mockResolvedValue({ id: "price_new_789" });
+
+      // Mock: checkout.sessions.create succeeds
+      mockStripe.checkout.sessions.create.mockResolvedValue({ 
+        id: "cs_existing", 
+        url: "https://checkout.stripe.com/pay/cs_existing" 
+      });
+
+      const res = await request(app)
+        .post("/v1/billing/checkout")
+        .send({});
+
+      expect(res.status).toBe(200);
+      expect(mockStripe.products.create).not.toHaveBeenCalled(); // Product exists, don't create
+      expect(mockStripe.prices.create).toHaveBeenCalledWith({
+        product: "prod_existing",
+        unit_amount: 900,
+        currency: "eur",
+        recurring: { interval: "month" },
+      });
+      expect(mockStripe.checkout.sessions.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          line_items: [{ price: "price_new_789", quantity: 1 }],
+        })
+      );
+    });
+  });
+});