This skill should be used when the user asks to "design a test strategy", "figure out our testing approach for this feature", "how much should we test this", "what's our test plan for this release", or needs to decide test-level allocation and where to focus coverage before writing any actual tests. Use for planning what to test and how much, at the feature or release level — not for writing or debugging individual tests (see e2e-testing for Playwright execution, test-driven-development for red-green-refactor at the unit level).