message: API: Fix getRandomUnitFromCourse
  Didn't always work before because the course.lectures may not be populated.
diff: @@ -150,12 +150,8 @@ export class FixtureUtils {
  }
  public static async getRandomUnitFromCourse(course: ICourse, hash?: string): Promise<IUnit> {
  - let units: Array<IUnit> = [];
  - for (const lecture of course.lectures) {
  - units = units.concat(lecture.units);
  - }
  - const unitId = await this.getRandom<IUnit>(units, hash);
  - return Unit.findById(unitId);
  + const units = await Unit.find({_course: course});
  + return await this.getRandom<IUnit>(units, hash);
  }
  /**
  