How to unit test a method in a sequelize model file?

Question

I need to create some unit tests for a method in my auth.model file. I was able to get some simple assertions done with sequelize-test-helpers, however I'm not sure how to call/test the method Auth.updateForgotPassword. I was told that I need to setup a mock connection to the DB so I can then use the method within the file. Refactoring the code is not an option at the moment. This is a node.js app using sequelize to map to a Postgres database.

auth.model.js

'use strict';
const Sequelize = require('sequelize');
const { forgotPassword } = require('../util/forgotPasswordCognitoHelper');
const { getErrorResponse } = require('../util/errorStatusHelper');

module.exports = (sequelize, DataTypes) => {
  const Auth = sequelize.define(
    'Auth',
    {
      userId: {
        type: DataTypes.INTEGER,
        primaryKey: true,
        field: 'user_id',
      },

      principalId: {
        type: DataTypes.TEXT,
        field: 'principal_id',
      },
    },

    {
      tableName: 'user_auth',
      timestamps: false,
      paranoid: false,
      version: false,
      sequelize,
    }
  );

  Auth.associate = function (models) {
    models.Auth.belongsTo(models.User, {
      foreignKey: 'userId',
      sourceKey: 'userId',
    });
  };

  Auth.updateForgotPassword = async function (args = {}) {
    const Models = require('./index');
    const response = {
      status: 'NOT_FOUND',
    };

    try {
      const auth = await Models.Auth.findOne({
        where: { principalId: args.username },
      });

      if (auth) {
        await forgotPassword(
          args.username,
          args.password,
          args.confirmationCode
        );

        response.status = 'SUCCESS';
      }
    } catch (ex) {
      response.status = getErrorResponse(ex);
      console.log(ex);
    }
    return response;
  };

  return Auth;
};

auth.test.js

const { expect } = require('chai')
const { match, stub, resetHistory } = require('sinon')
const proxyquire = require('proxyquire')
const {
  sequelize,
  dataTypes,
  checkModelName,
  checkPropertyExists,
} = require('sequelize-test-helpers')

describe('Auth Model Test Suite', function () {

  const AuthModel = require('../../../models/auth.model')
  const Auth = AuthModel(sequelize, dataTypes)
  let auth

  this.beforeAll(function () {
    auth = new Auth()
  })

  describe('Model name', function () {
    checkModelName(Auth)('Auth')
  })

  describe('Model properties', function () {
    auth = new Auth();
    ['userId',
      'principalId'
    ].forEach(checkPropertyExists(auth));
  })

})