import { MessageFunctionType, Result } from '../types';
export interface ContainsErrors {
    TARGET_ARGUMENT_NOT_A_STRING: MessageFunctionType;
    CONTAINED_ARGUMENT_NOT_A_STRING: MessageFunctionType;
}
export declare const CONTAINS_ERRORS: ContainsErrors;
/**
 * Test whether the `target` string
 * contains the `contained` string.
 *
 * ### Example
 * ```
 * expect(contains('foobar', 'foo').value).toBeTruthy()
 * ```
 * @param target The string that should contain the element
 * @param contained The possibly contained string
 */
export declare function contains(target: string, contained: string): Result<boolean | undefined>;