testing-patterns

★ 108

by langchain-ai · part of langchain-ai/skills-benchmarks

Unit testing and integration testing best practices

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🧩 One of 7 skills in the langchain-ai/skills-benchmarks package — works on its own, and pairs well with its siblings.

This is the playbook your agent receives when the skill activates — you don't need to read it to use the skill, but it's here to audit before installing.

Testing Patterns

Write effective, maintainable tests using modern patterns.

Test Structure (AAA Pattern)

def test_user_registration():
    # Arrange
    user_data = {"email": "test@example.com", "password": "secure123"}

    # Act
    result = register_user(user_data)

    # Assert
    assert result.success is True
    assert result.user.email == "test@example.com"

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": "test@example.com"})

    mock_send.assert_called_once_with(
        to="test@example.com",
        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