Shopify App Testing

Reliable testing is crucial for ensuring your app handles Shopify's authentication and API quirks correctly.

1. Unit & Integration Testing (Vitest + Remix)

Use Vitest for running unit and integration tests in the Remix environment.

Setup

Install dependencies:

npm install -D vitest @testing-library/react @testing-library/jest-dom jsdom

Mocking shopify.server.ts

Creating a mock for the authenticate object is critical for testing loaders and actions without hitting real Shopify APIs.

// test/mocks/shopify.ts
import { vi } from 'vitest';

export const mockShopify = {
  authenticate: {
    admin: vi.fn(),
    public: vi.fn(),
    webhook: vi.fn(),
  },
};

// Usage in test file:
vi.mock('../app/shopify.server', () => mockShopify);

test('loader returns data for authenticated shop', async () => {
    mockShopify.authenticate.admin.mockResolvedValue({
        currentShop: 'test-shop.myshopify.com',
        session: { shop: 'test-shop.myshopify.com', accessToken: 'fake_token' },
        admin: {
             graphql: vi.fn().mockResolvedValue({ /* mock response */ })
        }
    });

    const response = await loader({ request: new Request('http://localhost/') });
    // Assertions...
});

2. Testing Loaders & Actions

Using Remix's createRemixStub or calling loaders/actions directly is the best way to test backend logic.

Direct Function Call (Preferred for logic)

You can import the loader or action and call it directly with a mock Request.

import { loader } from '../app/routes/app.dashboard';

test('dashboard loader returns stats', async () => {
   // Setup mocks...
   const response = await loader({ 
       request: new Request('http://localhost/app/dashboard'), 
       params: {} 
   });
   const data = await response.json();
   expect(data.stats).toBeDefined();
});

3. End-to-End (E2E) Testing (Playwright)

For E2E tests, you need to handle the OAuth flow or bypass it using session tokens.

Bypassing Auth (Session Token)

The most stable way to E2E test embedded apps is to generate a valid session token (or mock the validation) so you don't have to automate the Login screen interaction which often triggers captchas.

Basic Playwright Test

import { test, expect } from '@playwright/test';

test('load dashboard', async ({ page }) => {
  await page.goto('http://localhost:3000/app');
  // Expect to see the Polaris Page title
  await expect(page.locator('.Polaris-Page-Header__Title')).toHaveText('Dashboard');
});

4. Testing Webhooks

To test webhooks locally:

1. Trigger via Shopify CLI: shopify app webhook trigger --topic ORDERS_CREATE
2. Unit Test: Import the webhook action and pass a mock Request with the correct HMAC header.

import { action } from '../app/routes/webhooks';
import crypto from 'crypto';

test('webhook verifies hmac', async () => {
    const payload = JSON.stringify({ id: 123 });
    const hmac = crypto.createHmac('sha256', 'FULL_SECRET').update(payload).digest('base64');
    
    const request = new Request('http://localhost/webhooks', {
        method: 'POST',
        body: payload,
        headers: { 'X-Shopify-Hmac-Sha256': hmac }
    });

    // Mock authenticate.webhook to succeed
    // ...
    
    const response = await action({ request });
    expect(response.status).toBe(200);
});