docfast/src/__tests__/billing-coverage-fix.test.ts

import { describe, it, expect, vi, beforeAll, afterAll, beforeEach } from "vitest";
import express from "express";
import request from "supertest";

// Mock Stripe ONCE before any imports
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(),
  },
};

vi.mock("stripe", () => {
  return { default: vi.fn(function() { return mockStripe; }) };
});

// Mock keys service
vi.mock("../services/keys.js", () => ({
  createProKey: vi.fn().mockResolvedValue({ 
    key: "pro-key-123", 
    tier: "pro", 
    email: "test@test.com", 
    createdAt: new Date().toISOString() 
  }),
  findKeyByCustomerId: vi.fn().mockResolvedValue(null),
  downgradeByCustomer: vi.fn().mockResolvedValue(undefined),
  updateEmailByCustomer: vi.fn().mockResolvedValue(true),
}));

// Set env BEFORE importing billing router (NO module reset!)
process.env.STRIPE_SECRET_KEY = "sk_test_fake_no_reset";
process.env.STRIPE_WEBHOOK_SECRET = "whsec_test_fake_no_reset";

// Import billing router ONCE
import { billingRouter } from "../routes/billing.js";
import { createProKey, findKeyByCustomerId } from "../services/keys.js";

let app: express.Express;

beforeAll(() => {
  // Setup Express app once
  app = express();
  app.use("/v1/billing/webhook", express.raw({ type: "application/json" }));
  app.use(express.json());
  app.use("/v1/billing", billingRouter);
});

beforeEach(() => {
  // Only clear mock calls, DON'T reset modules
  vi.clearAllMocks();
  
  // Reset default mock implementations
  mockStripe.products.search.mockResolvedValue({ data: [{ id: "prod_TygeG8tQPtEAdE" }] });
  mockStripe.prices.list.mockResolvedValue({ data: [{ id: "price_existing_123" }] });
  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);
});

describe("Billing Coverage Fix - NO MODULE RESET", () => {
  describe("Line 231-233: checkout.session.completed webhook catch block", () => {
    it("should gracefully handle Stripe API error when retrieving session", async () => {
      mockStripe.webhooks.constructEvent.mockReturnValue({
        type: "checkout.session.completed",
        data: {
          object: {
            id: "cs_api_error",
            customer: "cus_api_error",
            customer_details: { email: "error@test.com" },
          },
        },
      });

      // Trigger the catch block: session.retrieve throws
      mockStripe.checkout.sessions.retrieve.mockRejectedValueOnce(new Error("Stripe API is down"));

      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(res.body.received).toBe(true);
      // Key should NOT be provisioned due to error
      expect(createProKey).not.toHaveBeenCalled();
    });
  });

  describe("Line 165: /success route !customerId branch", () => {
    it("should return 400 when customer is null", async () => {
      mockStripe.checkout.sessions.retrieve.mockResolvedValueOnce({
        id: "cs_null_cust",
        customer: null,
        customer_details: { email: "test@test.com" },
      });

      const res = await request(app).get("/v1/billing/success?session_id=cs_null_cust");
      
      expect(res.status).toBe(400);
      expect(res.body.error).toContain("No customer found");
    });
  });

  describe("Line 315: getOrCreateProPrice() else branch - create new product", () => {
    it("should create new product and price when none exist", async () => {
      // Clear cache by calling checkout with empty product list
      mockStripe.products.search.mockResolvedValueOnce({ data: [] });
      mockStripe.products.create.mockResolvedValueOnce({ id: "prod_new_123" });
      mockStripe.prices.create.mockResolvedValueOnce({ id: "price_new_456" });
      mockStripe.checkout.sessions.create.mockResolvedValueOnce({ 
        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" },
      });
    });
  });
});