import { Locator, WebDriver } from 'selenium-webdriver';
import { Expectation } from './Expectation';
/**
 * Assert a given expectation against a JET application's viewmodel.
 * Assertions are [Chai](https://www.chaijs.com)-like expressions, represented
 * by the {@link Expectation} class, and compared remotely on the test browser
 * against the identified viewmodel and its path to the target value.
 *
 * The viewmodel is typically identiied by the DOM node on which Knockout's
 * <code>ko.applyBindings</code> was called, but can also be descendants of
 * that originial "root" node.
 * ```javascript
 * new Expectation(...)
 * ```
 *
 * The target value within the viewmodel is identified by a dot-notated path
 * and/or expression which yields the value. For instance, a value may be an
 * observable, therefore, the expression must include parenthesis to unwrap
 * the observable.
 * ```javascript
 * new Expecation(By.id('view-container'), 'firstName()')
 * ```
 *
 * The expression to which the viewmodel value will be compared is expressed
 * as BDD-style chains, such as
 * ```javascript
 * const fnExpectation = new Expectation('firstName()')
 *   .to.equal('Joe');
 * ```
 *
 * If a viewmodel value returns a Promise, the assertion will wait for it to
 * resolve before doing the comparison.
 *
 * @param driver The instance of WebDriver to use in performing the expectation
 * @param vmLocator The Locator which identifies the DOM node associated with the
 * viewmodel on the client.
 * @param expression The path within the viewmodel to locate the value
 * @param expectation The Expectation object to evaluate on the client browser.
 */
export declare function assertViewModelValue(driver: WebDriver, vmLocator: Locator, expectation: Expectation): Promise<any>;