TypeError: nemo.accessibility.scan(...).then is not a function

[fgeorge]

I am trying to do some accessibility testing for a web app and am currently stuck with the following issue.
TypeError: nemo.accessibility.scan(...).then is not a function
The versions of node and node modules used are as below.
node 8.9.4
"mocha": "4.1.0",
"nemo": "3.0.1",
"nemo-accessibility": "2.0.1",
"nemo-view": "2.2.3"

I have confirmed AATT server is up and running on localhost:3000.

below is the example code that will reproduce the error.
spec.js

var basedir = require('path').resolve(__dirname, '..');
var Nemo = require('nemo');
var nemo;
describe('accessibility test suite', function () {
    before(function (done) {
        nemo = Nemo(basedir, function (err) {
            if (err) {
                return done(err);
            }
            done();
        });
    });
    after(function (done) {
        nemo.driver.quit().then(done);
    });
    it('should automate the browser', function (done) {
        nemo.driver.get(nemo.data.baseUrl);
        nemo.driver.sleep(3000);
        nemo.accessibility.scan().then(function (result) {
            var file = process.cwd() + '/example/report/entirePage.html';
            fs.writeFile(file, result, function (err) {
                console.log('Successfully wrote the file ' + file);
            });
        });
        nemo.driver.sleep(3000).then(function () {
            done();
        }, function (err) {
            done(err);
        })
    });
});

config.json

{
    "plugins": {
        "view": {
            "module": "nemo-view",
            "arguments": ["path:locator"]
        },
        "nemo-accessibility": {
            "module": "nemo-accessibility",
            "arguments": ["http://localhost:3000/evaluate"]
        }
    },
    "driver": {
        "browser": "chrome"
    },
    "data": {
        "baseUrl": "https://www.paypal.com/"
    }
}

run the test
node_modules/.bin/mocha test/functional/spec/*.js --timeout 30000 --reporter spec

error
TypeError: nemo.accessibility.scan(...).then is not a function

Looks like for some reason, scanElement in nemo-accessibility module is not returning a promise. I have tried specifying a particular element using the 'element' option but that also did not help.

[nikulkarni]

We are using webdriver promise manager in nemo-accessibility and it is deprecated in selenium 3.x (since you are using nemo 3.x). Will need to fix this and publish nemo-accessibility@3.x, will work on this soon and update it here

[mpnkhan]

Upgraded to adapt to Nemo4