I began enhancements by writing a few focused tests that captured desired behavior. cargo test ran constantly, and failures became invitations to clarify intent. Mocks were minimal, preferring real edges where feasible. When bugs appeared, I wrote a test first, reproduced the issue, and fixed it once with confidence. Over time, the suite felt like a quiet partner, catching regressions I would surely miss late at night. That safety net encouraged bolder refactors because I could move quickly without gambling with unseen consequences.
Flakiness eroded trust, so I replaced wall-clock sleeps with deterministic signals, injected clocks for temporal control, and seeded randomness predictably. I used temporary directories, unique ports, and isolation to prevent cross-test interference. Retries were last resorts, not bandages. With precise preconditions and explicit teardown, runs stabilized, and attention shifted back to real defects. Documenting expectations within tests taught future readers why a condition mattered. The result was quieter pipelines, reliable feedback, and a sense that the codebase respected its own rules rather than rolling dice during verification.
Benchmarks can lie when poorly framed. Using Criterion, I measured whole behaviors with realistic inputs, warmed caches properly, and reported variance clearly. When numbers looked suspicious, I simplified the scenario until the signal was trustworthy. Only then did I compare approaches. Many optimizations disappeared after measurement; a few endured and justified their complexity. Establishing a performance budget focused efforts on outcomes, not vanity metrics. With that discipline, I spent energy wisely and shipped code that felt faster to users, not just prettier in a spreadsheet.