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Testing Patterns

langchain-ai/testing-patterns

Unit testing and integration testing best practices

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on the repository, not the skill itself

Install

one command, takes just this skill from the repository
npx skills add https://github.com/langchain-ai/skills-benchmarks --skill testing-patterns

The instruction itself

6 sections, as written by the author

Testing Patterns

Write effective, maintainable tests using modern patterns.

Test Structure (AAA Pattern)

def test_user_registration():
    # Arrange
    user_data = {"email": "[email protected]", "password": "secure123"}

    # Act
    result = register_user(user_data)

    # Assert
    assert result.success is True
    assert result.user.email == "[email protected]"

Mocking External Services

from unittest.mock import Mock, patch

@patch('services.email.send_email')
def test_sends_welcome_email(mock_send):
    mock_send.return_value = True

    register_user({"email": "[email protected]"})

    mock_send.assert_called_once_with(
        to="[email protected]",
        template="welcome"
    )

Fixtures and Factories

import pytest
from factories import UserFactory

@pytest.fixture
def user():
    return UserFactory.create(role="admin")

@pytest.fixture
def authenticated_client(user):
    client = TestClient(app)
    client.login(user)
    return client

def test_admin_dashboard(authenticated_client):
    response = authenticated_client.get("/admin")
    assert response.status_code == 200

Integration Tests

@pytest.mark.integration
def test_full_checkout_flow(db_session, stripe_mock):
    # Create test data
    user = create_user()
    product = create_product(price=100)

    # Execute flow
    cart = add_to_cart(user, product)
    order = checkout(cart, payment_method="card")

    # Verify
    assert order.status == "completed"
    assert stripe_mock.charges.create.called

Test Coverage Goals

  • Unit tests: 80%+ coverage
  • Integration tests: Critical paths
  • E2E tests: Happy paths only

How to use it

Copy the folder

Take langchain-ai/testing-patterns from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

The agent identifies a skill by the name field in its header. Two skills with the same name cannot sit side by side — one of them will be ignored.