Test Patterns

What it does

When your agent uses it

• The user asks about writing unit tests
• Integration tests
• End-to-end tests
• Structuring test cases

Example prompts

• “Use the test-patterns skill to apply proven testing patterns — Arrange-Act-Assert (AAA), Given-When-Then, Test Data Builders, Object Mother…”
• “/test-patterns”

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

1. 1Fresh instances - Create new objects in each test
2. 2Reset mocks - Clear mock state between tests
3. 3Clean up - Remove side effects (files, database rows)
4. 4No shared mutable state - Avoid global variables

What it can do on your machine

Read from SKILL.md and the folder at commit d2e5c34. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md.

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Test Patterns loads about 1.8k tokens when it runs. Until then it costs about 156 tokens; SKILL.md has 414 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~156

When it runs · the whole SKILL.md, loaded when a task matches

~1.8k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from rohitg00/skillkit at commit d2e5c34, republished under its Apache-2.0 licence (© rohitg00). 414 words, ~1,762 tokens.

name

test-patterns

description

Applies proven testing patterns — Arrange-Act-Assert (AAA), Given-When-Then, Test Data Builders, Object Mother, parameterized tests, fixtures, spies, and test doubles — to help write maintainable, reliable, and readable test suites. Use when the user asks about writing unit tests, integration tests, or end-to-end tests; structuring test cases or test suites; applying TDD or BDD practices; working with mocks, stubs, spies, or fakes; improving test coverage or reducing flakiness; or needs guidance on test organization, naming conventions, or assertions in frameworks like Jest, Vitest, pytest, or similar.

version

1.0.0

triggers

test patterns, testing best practices, how to write tests, test structure, arrange act assert

tags

testing, patterns, quality, best-practices

difficulty

intermediate

estimatedTime

10

relatedSkills

testing/red-green-refactor, testing/anti-patterns

// Arrange - Set up test data and dependencies
const user = createTestUser({ role: 'admin' });
const service = new UserService(mockRepository);

// Act - Execute the code under test
const result = await service.updateRole(user.id, 'member');

// Assert - Verify the expected outcome
expect(result.role).toBe('member');
expect(mockRepository.save).toHaveBeenCalledWith(user);

describe('Shopping Cart', () => {
  describe('when adding an item', () => {
    it('should increase the item count', () => {
      // Given
      const cart = new Cart();

      // When
      cart.add({ id: '1', quantity: 2 });

      // Then
      expect(cart.itemCount).toBe(2);
    });
  });
});

// Builder function
function createTestOrder(overrides = {}) {
  return {
    id: 'order-123',
    status: 'pending',
    items: [],
    total: 0,
    ...overrides
  };
}

// Usage
const completedOrder = createTestOrder({ status: 'completed', total: 99.99 });
const emptyOrder = createTestOrder({ items: [] });

class TestUserFactory {
  static admin() {
    return new User({ role: 'admin', permissions: ALL_PERMISSIONS });
  }

  static guest() {
    return new User({ role: 'guest', permissions: [] });
  }

  static withSubscription(tier) {
    return new User({ subscription: { tier, active: true } });
  }
}

describe('isValidEmail', () => {
  const validCases = [
    'user@example.com',
    'user.name@domain.co.uk',
    'user+tag@example.org'
  ];

  const invalidCases = [
    '',
    'not-an-email',
    '@no-local.com',
    'no-domain@'
  ];

  test.each(validCases)('should accept valid email: %s', (email) => {
    expect(isValidEmail(email)).toBe(true);
  });

  test.each(invalidCases)('should reject invalid email: %s', (email) => {
    expect(isValidEmail(email)).toBe(false);
  });
});

describe('OrderService', () => {
  let service;
  let mockPaymentGateway;
  let mockInventory;

  beforeEach(() => {
    mockPaymentGateway = createMockPaymentGateway();
    mockInventory = createMockInventory();
    service = new OrderService(mockPaymentGateway, mockInventory);
  });

  afterEach(() => {
    jest.clearAllMocks();
  });
});

it('should send notification on order completion', async () => {
  const notifySpy = jest.spyOn(notificationService, 'send');

  await orderService.complete(orderId);

  expect(notifySpy).toHaveBeenCalledWith({
    type: 'order_completed',
    orderId: orderId
  });
});

src/
  services/
    UserService.ts
    UserService.test.ts    # Co-located tests

tests/
  integration/
    api.test.ts            # Integration tests
  e2e/
    checkout.spec.ts       # End-to-end tests

© rohitg00, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in packages/core/src/methodology/packs/testing/test-patterns of rohitg00/skillkit.

Open the folder on GitHubat commit d2e5c34