/// <reference types="node" />
/// <reference types="google-cloud__storage" />
import Storage from '@google-cloud/storage';
export default class Screenshot {
    urlPath_: string;
    /**
     * @param {string} urlPath The URL path to test
     */
    constructor(urlPath: string);
    /**
     * Captures a screenshot of the test URL and marks it as the new golden image
     */
    capture(): void;
    /**
     * Diffs a screenshot of the test URL with the existing golden screenshot
     */
    diff(): void;
    /**
     * Generates a unique hash from an image's contents
     * @param {!Buffer} imageBuffer The image buffer to hash
     * @return {string}
     * @private
     */
    generateImageHash_(imageBuffer: Buffer): string;
    /**
     * Returns the golden hash
     * @return {string|undefined}
     * @private
     */
    getGoldenHash_(): Promise<any>;
    /**
     * Returns the correct image path
     * @param {string} imageHash The image hash
     * @param {string} imageType The image type
     * @return {string|undefined}
     * @private
     */
    getImagePath_(imageHash: string, imageType: string): string | undefined;
    /**
     * Downloads an image from Google Cloud Storage
     * @param {string} gcsFilePath The file path on Google Cloud Storage
     * @return {Buffer}
     * @private
     */
    readImage_(gcsFilePath: string): Promise<any>;
    /**
     * Saves the golden hash
     * @param {string} goldenHash The hash of the golden image
     * @private
     */
    saveGoldenHash_(goldenHash: string): Promise<void>;
    /**
     * Saves the given image to Google Cloud Storage with optional metadata
     * @param {string} imagePath The path to the image
     * @param {!Buffer} imageBuffer The image buffer
     * @param {!Object=} customMetadata Optional custom metadata
     * @private
     */
    saveImage_(imagePath: string, imageBuffer: Buffer, customMetadata?: Storage.CustomFileMetadata): Promise<unknown>;
    /**
     * Takes a screenshot of the URL
     * @return {!Buffer}
     * @private
     */
    takeScreenshot_(): Promise<Buffer>;
}