Saving result in a file from vscode-extension unit-tests in Azure DevOps

I have a problem, again...

I try to make a test report from my continuous integration tests in Azure DevOps. I have written unit tests as described in:
https://code.visualstudio.com/api/working-with-extensions/testing-extension

I have written yml mostly as described here:
https://code.visualstudio.com/api/working-with-extensions/continuous-integration

Now I want to "publish" my test results... I think to publish them, I have to create an XML(or TRX) in one of the following formats: JUnit, NUnit 2, NUnit 3, Visual Studio Test (TRX) and xUnit 2. It seems I am limited how to create a reporter/testrunner or whatever... I don't get it.

The provided API of vscode looks like:

testRunner.configure({
    ui: "tdd",
    useColors: true
});

module.exports = testRunner;

The expected type for the API is:

 interface MochaSetupOptions {

        //milliseconds to wait before considering a test slow
        slow?: number;

        // timeout in milliseconds
        timeout?: number;

        // ui name "bdd", "tdd", "exports" etc
        ui?: string;

        //array of accepted globals
        globals?: any[];

        // reporter instance (function or string), defaults to `mocha.reporters.Dot`
        reporter?: any;

        // bail on the first test failure
        bail?: boolean;

        // ignore global leaks
        ignoreLeaks?: boolean;

        // grep string or regexp to filter tests with
        grep?: any;

        // colored output from test results
        useColors?: boolean;

        // causes test marked with only to fail the suite
        forbidOnly?: boolean;
    }

I think my best try was using that module https://www.npmjs.com/package/mocha-junit-reporter:

testRunner.configure({
    reporter: 'mocha-junit-reporter',
    reporterOptions: {
        mochaFile: './path_to_your/file.xml'
    }
});

I know it fits not the API as described, but when you have a look at the source code from the vscode-module:

function configure(opts) {
    mocha = new Mocha(opts);
}
exports.configure = configure;

So it fits the documentation of the "mocha-junit-reporter" module

let a: any = {
    ui: "tdd",
    reporter: "xunit",
    reporterOptions: {
        output: normalize(join(getExtensionRootPath(), "..", "TestResults", "unit-tests", os + ".xml")),
    }        
};

testRunner.configure(a);

this did it for me except for Linux I will edit this answer if get managed it for Linux too.