Guidance for WRITING unit and component tests well — React/Testing Library, Python/pytest, Go, and Vue, plus stack-agnostic regression-test patterns. A companion to code-review-edho-ferdian's test-quality-lens (which judges tests after they're written) and dev-kickoff-edho-ferdian's TEST stage (which mandates writing a failing test first but doesn't teach test-writing craft). Trigger phrases: "tulis test untuk component ini", "bagaimana test hook ini", "test yang bagus untuk fitur X", "tulis test pytest/Go/Vue untuk ini", or during dev-kickoff's TEST stage when the task needs concrete authoring guidance beyond "write a failing test."
