Testing Skill

Bonded to: testing-security-agent (Secondary)

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Quick Start

# Invoke testing skill
"Write unit tests for my user service"
"Set up integration tests with database"
"Configure load testing with k6"

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Testing Pyramid

            /\
           /E2E\       Few, slow, expensive
          /────\
         /Integration\  Some, medium speed
        /────────────\
       /  Unit Tests  \ Many, fast, cheap
      /────────────────\

Type	Coverage	Speed	Cost
Unit	80%+	Fast	Low
Integration	60%+	Medium	Medium
E2E	Critical paths	Slow	High

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Examples

Unit Test (pytest)

import pytest
from unittest.mock import Mock
from app.services.user_service import UserService

class TestUserService:
    @pytest.fixture
    def service(self):
        return UserService(db=Mock())

    def test_get_user_returns_user(self, service):
        service.db.get_user.return_value = {"id": 1, "name": "John"}

        result = service.get_user(1)

        assert result["name"] == "John"
        service.db.get_user.assert_called_once_with(1)

    def test_get_user_raises_when_not_found(self, service):
        service.db.get_user.return_value = None

        with pytest.raises(UserNotFoundError):
            service.get_user(999)

Integration Test

import pytest
from fastapi.testclient import TestClient
from app.main import app
from app.database import get_db

@pytest.fixture
def client(test_db):
    def override_get_db():
        return test_db
    app.dependency_overrides[get_db] = override_get_db
    with TestClient(app) as c:
        yield c

def test_create_and_get_user(client):
    # Create user
    response = client.post("/users", json={"email": "test@example.com"})
    assert response.status_code == 201
    user_id = response.json()["id"]

    # Get user
    response = client.get(f"/users/{user_id}")
    assert response.status_code == 200
    assert response.json()["email"] == "test@example.com"

Load Test (k6)

import http from 'k6/http';
import { check, sleep } from 'k6';

export const options = {
  stages: [
    { duration: '30s', target: 100 },
    { duration: '1m', target: 100 },
    { duration: '30s', target: 0 },
  ],
  thresholds: {
    http_req_duration: ['p(95)<200'],
    http_req_failed: ['rate<0.01'],
  },
};

export default function () {
  const res = http.get('http://localhost:8000/api/v1/users');
  check(res, {
    'status is 200': (r) => r.status === 200,
    'response time < 200ms': (r) => r.timings.duration < 200,
  });
  sleep(1);
}

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Troubleshooting

Issue	Cause	Solution
Flaky tests	Race conditions	Use mocks, fix async
Slow suite	Too many E2E	Optimize pyramid
Low coverage	Untested edges	Add boundary tests

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Resources

• pytest Documentation
• k6 Documentation
• Testing on the Toilet (Google)