Express.js
Error handling is the part of an Express app most developers test last — and it's the part that matters most when things go wrong in production. A well-tested error handling stack means your API never leaks stack traces to clients, always returns machine-readable error formats, and
Testing
Snapshot testing captures a rendered view as a reference image, then on every subsequent test run it re-renders the same view and compares the result pixel by pixel. Any mismatch—a font change, a shifted layout, an unexpected color—fails the test immediately and shows you a diff image.
Express.js
Authentication middleware is the most security-critical code in your Express application. A bug in your JWT validation could mean an attacker with an expired token can still access protected routes. A session middleware misconfiguration can leak one user's data to another. This post covers how to write
Testing
Exploratory testing without structure is just clicking around. Mind maps give you structure without the overhead of writing formal test cases — you get coverage breadth, session focus, and a record of what you explored, all in a format that takes minutes to build rather than hours. This post covers how
Testing
Events in Solidity are the communication layer between your smart contracts and the world outside the blockchain. Subgraphs index them. Front-ends listen for them. Off-chain services trigger workflows based on them. When an event is missing, emitted with wrong arguments, or emitted in the wrong order, the entire
Testing
After Log4Shell, the security community spent considerable energy debating how attackers got a vulnerable library into so many systems. The answer is uncomfortable: developers added it as a dependency, trusting that upstream had done the right thing. That trust had no cryptographic backing, no audit trail, and no way to
Testing
Example Mapping is a structured 25-minute workshop where a developer, tester, and product person use four colored cards — yellow (story), blue (rules), green (examples), red (questions) — to turn a vague user story into concrete, testable examples. The output maps directly to Gherkin scenarios. Stories that generate too many red
Testing
Event sourcing is a different mental model for state. Instead of reading and writing a current state, you store a sequence of events and derive current state by replaying them. This has testing implications: you test the events that commands produce, not the state mutations directly. The Testing Model In
Testing
Most test strategies are organized around features: we test what we build. SLO-driven testing flips this: you test what you've promised. If you've committed to 99.9% availability, your test suite should have an explicit answer to the question "how do we know we&
Testing
Event-driven serverless architectures are difficult to test for a specific reason: the chain of cause and effect spans multiple services, most of which are asynchronous. An HTTP request triggers a Lambda that publishes to SNS, which fans out to three SQS queues, each of which triggers a different Lambda
Testing
Your SLI implementation is code. Your alerting rules are code. Your Prometheus recording rules are code. All of it can and should be tested — before it goes into production, before an incident shows you that your alert fires three hours too late or routes to the wrong Slack channel. This
Testing
Event-driven systems fail in slow, invisible ways. A service publishes an event with a renamed field. The consumers don't know yet. Production breaks hours later when the queue drains. Your unit tests all pass because each service tests in isolation. This is the core challenge of EDA