message: Add method which is failed after merge
diff: import {User} from '../src/models/User';
  -import {Course} from '../src/models/Course';
  +import {Course, ICourseModel} from '../src/models/Course';
  import {Lecture} from '../src/models/Lecture';
  import {Unit} from '../src/models/units/Unit';
  import {ICourse} from '../../shared/models/ICourse';
  import {ILecture} from '../../shared/models/ILecture';
  import {IUnit} from '../../shared/models/units/IUnit';
  import {IUser} from '../../shared/models/IUser';
  +import * as mongoose from 'mongoose';
  +import ObjectId = mongoose.Types.ObjectId;
  export class FixtureUtils {
  public static async getRandomUser(hash?: string) {
  @@ -56,6 +58,19 @@ export class FixtureUtils {
  return this.getRandomArray(array, min, max, hash);
  }
  + public static async getRandomWhitelistUsers(students: IUser[], course: ICourseModel, hash?: string) {
  + const randomArray = students.splice(0, this.getRandomNumber(0, students.length - 1));
  + const array = await this.getRandomArray(randomArray, 0, students.length - 1, hash);
  + return array.map( (stud: IUser) => {
  + return {
  + firstName: stud.profile.firstName,
  + lastName: stud.profile.lastName,
  + uid: stud.uid,
  + courseId: new ObjectId(course._id)
  + }
  + });
  + }
  +
  public static async getRandomCourse(hash?: string) {
  const array = await this.getCourses();
  return this.getRandom(array, hash);
  