Performance testing

Performance Testing

Create comprehensive performance tests including load testing, stress testing, and benchmarking to validate system behavior under various conditions. This skill implements Phase 5 of the 8-phase testing methodology.

When to Use This Skill

Use this skill when you need to:

• Validate system performance requirements
• Identify performance bottlenecks
• Establish performance baselines
• Test system behavior under load
• Benchmark critical algorithms
• Measure response times and throughput
• Test scalability limits

Trigger phrases: "performance test", "load test", "stress test", "benchmark", "measure performance", "test throughput", "response time", "scalability test"

What This Skill Does

Performance Testing Types

Type	Purpose	Duration	Load Pattern
Load Testing	Validate under expected load	Minutes-hours	Constant/stepped
Stress Testing	Find breaking points	Until failure	Increasing
Spike Testing	Handle sudden surges	Seconds-minutes	Sharp peaks
Soak Testing	Long-term stability	Hours-days	Constant
Benchmark	Compare implementations	Seconds	Fixed iterations

Language-Specific Examples

Python (pytest-benchmark + locust)

import pytest
from myapp.algorithms import sort_data, search_data, process_batch

# ==================== BENCHMARKS ====================

class TestAlgorithmBenchmarks:
    """Benchmark tests for critical algorithms."""

    def test_sort_small_dataset(self, benchmark):
        """Benchmark sorting with small dataset."""
        data = list(range(1000, 0, -1))
        result = benchmark(sort_data, data)
        assert result == sorted(data)

    def test_sort_large_dataset(self, benchmark):
        """Benchmark sorting with large dataset."""
        data = list(range(100000, 0, -1))
        result = benchmark(sort_data, data)
        assert len(result) == 100000

    @pytest.mark.parametrize("size", [100, 1000, 10000])
    def test_search_performance(self, benchmark, size):
        """Benchmark search across different sizes."""
        data = list(range(size))
        target = size // 2
        result = benchmark(search_data, data, target)
        assert result == target

    def test_batch_processing_throughput(self, benchmark):
        """Measure batch processing throughput."""
        items = [{"id": i, "data": f"item_{i}"} for i in range(1000)]

        def process_all():
            return [process_batch(items[i:i+100]) for i in range(0, len(items), 100)]

        benchmark.pedantic(process_all, iterations=10, rounds=5)


# ==================== LOCUST LOAD TEST ====================
# locustfile.py

from locust import HttpUser, task, between

class APIUser(HttpUser):
    """Simulated API user for load testing."""
    wait_time = between(1, 3)

    def on_start(self):
        """Login at start of session."""
        response = self.client.post("/api/auth/login", json={
            "email": "[email protected]",
            "password": "testpass123"
        })
        self.token = response.json()["access_token"]
        self.headers = {"Authorization": f"Bearer {self.token}"}

    @task(3)
    def get_users(self):
        """Frequent: List users."""
        self.client.get("/api/users", headers=self.headers)

    @task(2)
    def get_user_detail(self):
        """Common: Get specific user."""
        self.client.get("/api/users/1", headers=self.headers)

    @task(1)
    def create_user(self):
        """Rare: Create new user."""
        self.client.post("/api/users", headers=self.headers, json={
            "name": "Load Test User",
            "email": f"loadtest_{time.time()}@example.com"
        })

    @task(1)
    def search_users(self):
        """Search with query parameter."""
        self.client.get("/api/users?q=test", headers=self.headers)

JavaScript/TypeScript (Artillery + Jest)

// benchmark.test.ts
import { performance } from 'perf_hooks';
import { sortData, searchData, processBatch } from '../src/algorithms';

describe('Algorithm Benchmarks', () => {
  const benchmark = (fn: () => void, iterations: number = 1000): number => {
    const start = performance.now();
    for (let i = 0; i < iterations; i++) {
      fn();
    }
    return (performance.now() - start) / iterations;
  };

  it('sorts small dataset under 1ms', () => {
    const data = Array.from({ length: 1000 }, (_, i) => 1000 - i);
    const avgTime = benchmark(() => sortData([...data]), 100);
    expect(avgTime).toBeLessThan(1);
  });

  it('searches large dataset under 0.1ms', () => {
    const data = Array.from({ length: 100000 }, (_, i) => i);
    const avgTime = benchmark(() => searchData(data, 50000), 1000);
    expect(avgTime).toBeLessThan(0.1);
  });

  it('processes batch with acceptable throughput', () => {
    const items = Array.from({ length: 1000 }, (_, i) => ({ id: i }));
    const start = performance.now();
    processBatch(items);
    const duration = performance.now() - start;
    const throughput = items.length / (duration / 1000);
    expect(throughput).toBeGreaterThan(10000); // 10k items/sec
  });
});

// artillery.yml - Load test configuration
/*
config:
  target: "http://localhost:3000"
  phases:
    - duration: 60
      arrivalRate: 10
      name: "Warm up"
    - duration: 120
      arrivalRate: 50
      name: "Sustained load"
    - duration: 60
      arrivalRate: 100
      name: "Peak load"

scenarios:
  - name: "User workflow"
    flow:
      - post:
          url: "/api/auth/login"
          json:
            email: "[email protected]"
            password: "test123"
          capture:
            - json: "$.token"
              as: "authToken"
      - get:
          url: "/api/users"
          headers:
            Authorization: "Bearer {{ authToken }}"
      - get:
          url: "/api/users/1"
          headers:
            Authorization: "Bearer {{ authToken }}"
*/

Java (JMH)

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
import java.util.concurrent.TimeUnit;

@State(Scope.Benchmark)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Warmup(iterations = 3, time = 1)
@Measurement(iterations = 5, time = 1)
@Fork(1)
public class AlgorithmBenchmark {

    @Param({"100", "1000", "10000"})
    private int size;

    private int[] data;

    @Setup
    public void setup() {
        data = new int[size];
        for (int i = 0; i < size; i++) {
            data[i] = size - i;
        }
    }

    @Benchmark
    public int[] benchmarkSort() {
        return Algorithms.sort(data.clone());
    }

    @Benchmark
    public int benchmarkSearch() {
        return Algorithms.binarySearch(data, size / 2);
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    @OutputTimeUnit(TimeUnit.SECONDS)
    public void benchmarkBatchProcessing() {
        Algorithms.processBatch(data);
    }

    public static void main(String[] args) throws Exception {
        Options opt = new OptionsBuilder()
            .include(AlgorithmBenchmark.class.getSimpleName())
            .build();
        new Runner(opt).run();
    }
}

Prerequisites

• Functional tests passing
• Understanding of performance requirements
• Production-like test environment
• Baseline metrics established

Instructions

Step 1: Define Performance Requirements

1. Response Time Targets

   • P50, P95, P99 latency
   • Maximum acceptable latency

2. Throughput Targets

   • Requests per second
   • Transactions per minute

3. Resource Limits

   • CPU utilization
   • Memory usage
   • Connection pools

Step 2: Create Benchmarks

1. Identify Critical Paths

   • Hot code paths
   • Frequently called functions
   • Data processing algorithms

2. Write Benchmark Tests

   • Measure execution time
   • Track memory allocation
   • Compare implementations

Step 3: Implement Load Tests

1. Define Scenarios

   • User workflows
   • API call patterns
   • Realistic data volumes

2. Configure Load Profiles

   • Ramp-up period
   • Sustained load
   • Peak scenarios

Quality Checklist

• Performance requirements documented
• Critical paths benchmarked
• Load test scenarios defined
• Baseline metrics established
• Bottlenecks identified
• Results documented with graphs

Related Skills

• unit-tests - Unit testing (Phase 2)
• cicd-integration - CI/CD setup (Phase 6)
• code-coverage - Coverage analysis (Phase 7)

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Version: 1.0.0 Last Updated: December 2025 Based on: AI Templates tests_generation/performance_testing/

Iterative Refinement Strategy

This skill is optimized for an iterative approach:

1. Execute: Perform the core steps defined above.
2. Review: Critically analyze the output (coverage, quality, completeness).
3. Refine: If targets aren't met, repeat the specific implementation steps with improved context.
4. Loop: Continue until the definition of done is satisfied.