Spike: extract a shared component-render test helper to reduce test harness duplication

[kmcginnes]

Description

Multiple component test files duplicate the same render-wrapper pattern: create a QueryClient, wrap the component in QueryClientProvider + jotai Provider + TooltipProvider, seed state via DbState.applyTo(store). This pattern appears at least in SchemaExplorerSidebar.test.tsx, Styles.test.tsx, and others with similar shape.

The seam is: a render function that wraps any component in the standard required context providers, given a DbState to seed. Today every test file re-derives this boilerplate.

Questions to investigate

• What is the right abstraction boundary? A renderWithState(component, state) that returns the standard render() result? Or a reusable wrapper-component factory?
• Should it compose with the existing renderHookWithState (which already handles the Jotai store + QueryClient for hook tests)? Is there a unified TestProvider that both can share?
• Does the vi.mock("react-virtuoso", ...) block (also duplicated across files that render Virtuoso lists) belong in a shared mock utility, or should it stay per-file since mocking has test-file scope?
• What about the getAppStore() call — should the helper own creating a fresh store, or should callers still pass one?

Desired outcome

A concrete recommendation (with a sketch) for a @/utils/testing helper that reduces component-test boilerplate without coupling tests to each other. The helper should be opt-in (existing tests don't break if they don't adopt it) and composable with DbState.

Related

• Observed in Combine node and edge styling into one Styles sidebar #1914 (Combine styling sidebars) — renderStyles and renderSidebar are near-identical.
• renderHookWithState already solves the hook-level version of this pattern.

Important

Internal only — this issue is maintained by the core team and is not accepting external contributions.