import type { TemplateResult } from 'lit';
/**
 * Creates a new testing fixture.
 *
 * - If React is available the fixture will be wrapped in a React app.
 * - By default standard a fixture will be created using lit html.
 * @param code The element code you'd like to generate a fixture for.
 * @returns  Returns the new web component fixture rendered and ready for tests.
 */
export declare function createFixture<T extends Element = HTMLElement>(code: string | TemplateResult): Promise<T>;
declare global {
    namespace Chai {
        interface Assertion {
            /**
             * Given a CSS color string, assert that it matches the expected value.
             * Color strings are normalized using colorjs.io
             */
            colored(expected: string, msg?: string): void;
        }
    }
}