testinglisted

# Testing Skill Write tests that follow the project's established patterns. Every domain function, hook, and user-facing component must be tested. ## Test Layers ### Domain Tests (`app/domain/<feature>.test.ts`) Pure Vitest tests against pure functions. No React, no DOM, no mocks. ```ts import { describe, it, expect } from "vitest"; import { myFunction, MY_CONSTANT } from "~/domain/my-feature"; describe("myFunction", () => { it("returns expected result for valid input", () => { const result = myFunction(input); expect(result.score).toBe(4); // comment explaining calculation }); it("returns null for invalid input", () => { expect(myFunction(invalid)).toBeNull(); }); }); ``` **Rules:** - Import only from `vitest` and `~/domain/*` - Use real constants from domain (no mocks) - Add inline comments explaining non-obvious calculations - Test edge cases: zero values, max values, null/invalid returns - Group related tests in `describe` blocks ### Hook Tests (`app/hooks/<hook>.test.ts`) Use `renderHook` from Testing Library. Wrap state changes in `act()`. ```ts import { renderHook, act } from "@testing-library/react"; import { describe, it, expect } from "vitest"; import { useMyHook } from "~/hooks/use-my-hook"; describe("useMyHook", () => { it("has correct initial state", () => { const { result } = renderHook(() => useMyHook()); expect(result.current.value).toBe(0); }); it("updates state correctly", () => { const { result } = renderHo