copilot-instructions: Instructions file for GitHub Copilot

Frameworks

Prefer Playwright (web); Cypress as alternative; SpecFlow (BDD .NET); xUnit/NUnit for .NET integration; Jest/Vitest for JS; configure in docker‑compose for CI/CD; use Testcontainers when possible.

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

test('user can login', async ({ page }) => {
  await page.goto('/login');
  await page.fill('[data-testid="email"]', '[email protected]');
  await page.fill('[data-testid="password"]', 'password');
  await page.click('[data-testid="submit"]');
  await expect(page).toHaveURL('/dashboard');
});

Test Structure

MANDATORY AAA Pattern: All tests MUST follow Arrange-Act-Assert pattern for clarity and maintainability.

AAA Rules (Universal - All Languages):

• Arrange: Setup test data, mocks, preconditions, and initial state
• Act: Execute ONE operation being tested
• Assert: Verify ONE logical outcome (multiple assertions OK if related)
• Comments: Add explanatory note below AAA marker ONLY for critical/complex logic
  • Simple operations: NO extra comments needed
  • Complex logic: Add brief explanation of WHY or WHAT makes it critical
  • Avoid: Redundant descriptions of obvious operations

// C# Example
[Test]
public async Task Should_CreateOrder()
{
    // Arrange
    // Setup: prepare API client and valid order
    var client = _factory.CreateClient();
    var order = OrderFactory.CreateValid();

    // Act
    // Execute: send POST request
    var response = await client.PostAsJsonAsync("/orders", order);

    // Assert
    // Verify: successful creation with correct status
    response.StatusCode.Should().Be(HttpStatusCode.Created);
    var created = await response.Content.ReadAsAsync<Order>();
    created.Id.Should().BeGreaterThan(0);
}

// TypeScript/Playwright Example
test('user can complete checkout', async ({ page }) => {
  // Arrange
  // Setup: login and add items to cart
  await loginAsUser(page, '[email protected]');
  await addItemToCart(page, 'product-123');

  // Act
  // Execute: complete checkout process
  await page.click('[data-testid="checkout-btn"]');
  await fillPaymentDetails(page);
  await page.click('[data-testid="place-order"]');

  // Assert
  // Critical: verify order confirmation and inventory update
  await expect(page.locator('[data-testid="order-success"]')).toBeVisible();
  await expect(page).toHaveURL(/\/orders\/\d+/);
});