webdriverio/wdio-selenium-standalone-service

import path from 'path'

const FILE_EXTENSION_REGEX = /\.[0-9a-z]+$/i

/**
 * Resolves the given path into a absolute path and appends the default filename as fallback when the provided path is a directory.
 * @param  {String} logPath         relative file or directory path
 * @param  {String} defaultFilename default file name when filePath is a directory
 * @return {String}                 absolute file path
 */
export default function getFilePath (filePath, defaultFilename) {
    let absolutePath = path.resolve(filePath)

    // test if we already have a file (e.g. selenium.txt, .log, log.txt, etc.)
    // NOTE: path.extname doesn't work to detect a file, cause dotfiles are reported by node to have no extension
    if (!FILE_EXTENSION_REGEX.test(path.basename(absolutePath))) {
        absolutePath = path.join(absolutePath, defaultFilename)
    }

    return absolutePath
}