chore(api): gatekeep timer start at and set test

- if submission already has timer started at, we won't allow to re-configure it
- add test cases regarding this API

app/controllers/course/assessment/submission/submissions_controller.rb

@@ -108,17 +108,17 @@ def generate_live_feedback
  end
 
  def set_timer_started_at
- timer_started_at = Time.zone.now
+ unless @submission.timer_started_at
+ @submission.timer_started_at = Time.zone.now
 
- @submission.timer_started_at = timer_started_at
+  raise ActiveRecord::Rollback unless @submission.save
 
- raise ActiveRecord::Rollback unless @submission.save
-
- Course::Assessment::Submission::ForceSubmitTimedSubmissionJob.
- set(wait_until: timer_started_at + @assessment.time_limit.minutes + FORCE_SUBMIT_DELAY).
- perform_later(@assessment, @submission_id, @submission.creator)
+ Course::Assessment::Submission::ForceSubmitTimedSubmissionJob.
+ set(wait_until: @submission.timer_started_at + @assessment.time_limit.minutes + FORCE_SUBMIT_DELAY).
+ perform_later(@assessment, @submission_id, @submission.creator)
+ end
 
- render json: { timerStartedAt: timer_started_at }
+ render json: { timerStartedAt: @submission.timer_started_at }
  end
 
  # Reload the current answer or reset it, depending on parameters.

spec/controllers/course/assessment/submission/submissions_controller_spec.rb

@@ -240,6 +240,55 @@
  end
  end
 
+ describe '#set_timer_started_at' do
+ let!(:assessment) { create(:assessment, :published, *assessment_traits, course: course, time_limit: 120) }
+ let!(:assessment2) { create(:assessment, :published, *assessment_traits, course: course, time_limit: 120) }
+ let!(:submission) { create(:submission, :attempting, assessment: assessment, creator: user) }
+ let!(:submission2) do
+ create(:submission, :attempting, assessment: assessment2, creator: user,
+ timer_started_at: Time.zone.now - 5.seconds)
+ end
+
+ context 'when user first-time attempt the timed assessment' do
+ subject do
+ patch :set_timer_started_at, params: {
+ course_id: course, assessment_id: assessment.id, id: submission.id
+ }
+ end
+
+ it 'assigns the timer_started_at to current time' do
+ subject
+ json_result = JSON.parse(response.body)
+ expect(json_result['timerStartedAt'].to_datetime.utc).to \
+ be_within(1.second).of Time.zone.now.utc
+ expect(submission.reload.timer_started_at.utc).to \
+ be_within(1.second).of Time.zone.now.utc
+ end
+ end
+
+ context 'when user has already attempted the timed assessment before' do
+ subject do
+ patch :set_timer_started_at, params: {
+ course_id: course, assessment_id: assessment2.id, id: submission2.id
+ }
+ end
+
+ it 'assigns the timer_started_at to current time' do
+ subject
+ json_result = JSON.parse(response.body)
+ expect(json_result['timerStartedAt'].to_datetime.utc).not_to \
+ be_within(1.second).of Time.zone.now.utc
+ expect(submission2.reload.timer_started_at.utc).not_to \
+ be_within(1.second).of Time.zone.now.utc
+
+ expect(json_result['timerStartedAt'].to_datetime.utc).to \
+ be_within(1.second).of (Time.zone.now - 5.seconds).utc
+ expect(submission2.reload.timer_started_at.utc).to \
+ be_within(1.second).of (Time.zone.now - 5.seconds).utc
+ end
+ end
+ end
+
  describe 'submission_actions' do
  let!(:students) { create_list(:course_student, 5, course: course) }
  let!(:phantom_student) { create(:course_student, :phantom, course: course) }