Scala
Akka TestKit provides specialised tools for testing actor-based systems: TestProbe intercepts messages, expectMsg asserts on received messages with configurable timeouts, and TestFSMRef exposes FSM internals for white-box testing. This post covers every layer from simple unit tests to complex multi-actor scenarios. Testing actors is fundamentally different from
Kotlin
Espresso is Android's UI testing framework, executing tests directly on a device or emulator. This guide covers the full Espresso toolkit: ViewMatchers for finding views, ViewActions for interacting, ViewAssertions for validating state, IdlingResources for async synchronization, and Hilt for injecting test dependencies. Unit tests tell you your logic
Elixir
Phoenix LiveView's test module gives you a full server-side rendering environment without a browser. This post covers mounting views, simulating user interactions, testing navigation, form submission, JS hook callbacks, and real-time push events — all in fast, deterministic ExUnit tests. LiveView moved the rendering loop to the
Spring Boot
Spring Security is the most undertested layer in most Spring Boot apps. This post shows how to use @WithMockUser, @WithSecurityContext, mockJwt(), and method security tests to actually verify your authorization rules. Security is the layer where bugs have the worst consequences — an unprotected endpoint or a misconfigured role check is
Spring Boot
@DataJpaTest loads only the JPA layer — no controllers, no services, no security. Pair it with TestEntityManager for precise fixture control, and Testcontainers PostgreSQL when H2 is not enough. This post covers all the patterns you need for a solid repository test suite. The repository layer is where your application talks
Testing
Docker Compose is the standard way to run multi-service integration tests locally and in CI. Use docker compose up --wait with healthchecks to ensure services are ready before tests run. Run tests against the composed services from the host or from a test runner container. Always clean up with
Testing
* Artillery uses YAML config files to define load scenarios and HTTP targets * artillery-pro / cloud mode distributes load across multiple worker machines * AWS Lambda backend lets you generate load without managing servers * Results from all workers are aggregated into a single report * Regression detection compares p95/p99 latency against baseline
Testing
Agentic AI evaluation goes beyond single-turn accuracy. Measure task completion rate, tool-call precision/recall, step efficiency, and trajectory quality. A 90% single-turn accuracy agent can still fail 40% of multi-step tasks due to error propagation. Evaluate the full trajectory, not just the final answer. Single-turn
LibFuzzer
LibFuzzer is LLVM's built-in coverage-guided fuzzer for C and C++. Unlike AFL++, which runs as a separate process, LibFuzzer runs inside your program's process — making it 10-20x faster. It's integrated directly into Clang, requires no external tools, and is used by
AFL++
AFL++ (American Fuzzy Lop++) is the most widely used coverage-guided fuzzer for C and C++ programs. It instruments your binary at compile time to track code coverage, then mutates inputs guided by that coverage to explore your program's logic exhaustively. Used by Google, Mozilla, and security researchers
Flutter
Flutter integration tests run your full app on a real device or emulator — no mocks, no shortcuts. This guide covers the integration_test package from scratch: setup, writing tests, managing app state between tests, running on CI, and gotchas that will save you hours of debugging. Key Takeaways * integration_test
Flutter
Flutter widget tests let you verify UI components in isolation — faster than integration tests, more reliable than manual checks. This guide covers the full flutter_test toolkit: testWidgets, WidgetTester, pump/pumpAndSettle, finders, and matchers with production-ready code examples. Key Takeaways * Widget tests run in a simulated environment — no emulator