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H2 in-memory databases don't catch PostgreSQL-specific bugs. Mocked message brokers don't verify producer and consumer integration. Testcontainers runs real infrastructure in Docker during tests, eliminating the gap between what passes locally and what breaks in production.
Read moreThe builder pattern solves real problems with telescoping constructors and optional parameters. It also introduces indirection, deferred validation, and maintenance overhead that aren't always worth the tradeoff.
Read moreDecorators solve the problem of adding behavior to objects without subclassing, but Ruby gives you several ways to implement them — each with different tradeoffs around interface fidelity, performance, and testability.
Read moreConditional dispatch — switching on a type or status to select behavior — is the most common source of rigid code in Java applications. The strategy pattern replaces the switch with polymorphism, but the right implementation depends on what varies and how often it changes.
Read moreJava generics are a compile-time feature. By the time your code runs, most generic type information is gone. Understanding exactly what survives and what doesn't explains a category of bugs and design constraints that otherwise seem arbitrary.
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