Example wdio config file where onComplete does not wait for the async operation

gistfile1.txt

exports.config = {
    runner: 'local',
    specs: [ 'test.js'],
    maxInstances: 2,
    exclude: [],
    hostname: 'localhost',
    port: 4444,
    path: '/wd/hub',
    capabilities: [
        {
            browserName: 'chrome',
            "goog:chromeOptions" : {
                "args" : [
                    "no-sandbox"
                ]
            }
        }
    ],
    outputDir: './wdiologs/',
    deprecationWarnings: true,
    bail: 0,
    logLevel: 'info',
    coloredLogs: true,
    waitforTimeout: 10000,
    connectionRetryTimeout: 20000,
    connectionRetryCount: 3,
    framework: 'mocha',
    mochaOpts: {
        ui: 'bdd'
    },
    onPrepare: async function(config, capabilities) {
        console.log("onPrepare() - Pre 10s Wait: " + Date.now());
        await new Promise(resolve => setTimeout(resolve, 10000));
        console.log("onPrepare() - Post 10s Wait: " + Date.now());
    },
    onComplete: async function (exitCode, config, capabilities, results) {
        console.log("onComplete() - Pre 10s Wait: " + Date.now());
        await new Promise(resolve => setTimeout(resolve, 10000));
        console.log("onComplete() - Post 10s Wait: " + Date.now());
    }
}