message: API: Reinforce exportAccessDenialSetup
diff: @@ -29,10 +29,10 @@ const testHelper = new TestHelper(BASE_URL);
  /**
  * Provides simple shared setup functionality used by the export access denial unit tests.
  *
  - * @returns A course and an unauthorizedTeacher (i.e. a teacher that isn't part of the course).
  + * @returns A course with at least one unit/lecture and an unauthorizedTeacher (i.e. a teacher that isn't part of the course).
  */
  async function exportAccessDenialSetup() {
  - const course = await FixtureUtils.getRandomCourse();
  + const course = await FixtureUtils.getRandomCourseWithAllUnitTypes();
  const unauthorizedTeacher = await User.findOne({
  _id: {$nin: [course.courseAdmin, ...course.teachers]},
  role: 'teacher'
  