component-fixtures

Create a file ending in .fixture.ts under src/vs/workbench/test/browser/componentFixtures that exports a default defineThemedFixtureGroup. Each fixture uses defineComponentFixture with a render function, and the Vite dev server auto-discovers it via the src/**/*.fixture.ts glob.

Use createEditorServices with an additionalServices callback to register implementations or instances via reg.define and reg.defineInstance. For mocks, extend the mock<T>() helper from base/test/common/mock.js and override only the methods your component calls.

Flickering usually comes from reparenting DOM nodes after the initial render, which triggers layout recalculation and focus loss. Build the correct DOM structure up front and render the widget in place instead of moving it after async waits.

Fixtures render inside shadow DOM, so CSS rules scoped to deep ancestor selectors like .workbench .sidebar .my-widget will not match. Recreate the expected ancestor classes in the fixture or refactor the component CSS to self-contained selectors.

Yes, pass fileIconTheme to defineComponentFixture, for example 'vs-minimal' or 'none' to disable icons. Fixtures use Seti file icons by default, and the selected theme should also be forwarded to createEditorServices when the component reads IThemeService.