fix: check prerequisites for tasks with no upload requirement

app/api/submission/portfolio_evidence_api.rb

@@ -18,16 +18,6 @@ def self.logger
       authenticated?
     end
 
-    TASK_STATES = {
-      ready_for_feedback: 1,
-      assess_in_portfolio: 1,
-      discuss: 2,
-      rediscuss: 2,
-      attention_required: 0,
-      demonstrate: 2,
-      complete: 3
-    }.freeze
-
     desc 'Upload and generate doubtfire-task-specific submission document'
     params do
       optional :file0, type: File, desc: 'file 0.'
@@ -53,32 +43,8 @@ def self.logger
         error!({ error: "This task requires a group submission. Ensure you are in a group for the unit's #{task_definition.group_set.name}" }, 403)
       end
 
-      # Check that prerequisite tasks are in the required minimum submitted state
-      prerequisites = task_definition.task_prerequisites
-      prerequisites.each do |prerequisite|
-        prereq_td = prerequisite.prerequisite
-        minimum_status = TaskStatus.find(prerequisite.task_status_id)
-
-
-        prereq_task = project.task_for_task_definition(prereq_td)
-
-        verb =
-          case minimum_status
-          when TaskStatus.complete
-            'completed'
-          when TaskStatus.discuss
-            'discussed'
-          when TaskStatus.rediscuss
-            'rediscussed'
-          when TaskStatus.demonstrate
-            'demonstrated'
-          when TaskStatus.ready_for_feedback
-            'submitted'
-          end
-
-        if !prereq_task.ready_or_complete? || TASK_STATES[prereq_task.status] < TASK_STATES[minimum_status.status_key]
-          error!({ error: "Cannot submit this task until prerequisite '#{prereq_td.abbreviation}' has been #{verb}" }, 409)
-        end
+      if (prerequisite_error = task.unmet_prerequisite_error)
+        error!({ error: prerequisite_error }, 409)
       end
 
       trigger = if params[:trigger] && params[:trigger].tr('"\'', '') == 'need_help'

app/api/tasks_api.rb

@@ -178,6 +178,11 @@ class TasksApi < Grape::API
           error!({ error: 'Cannot set this task status to ready to mark without uploading documents.' }, 403)
         end
 
+        if !needs_upload_docs && %w[ready_for_feedback assess_in_portfolio].include?(params[:trigger]) &&
+           (prerequisite_error = task.unmet_prerequisite_error)
+          error!({ error: prerequisite_error }, 409)
+        end
+
         if params[:trigger] == 'assess_in_portfolio' && !authorise?(current_user, project, :assess)
           # Prevent students from upading status if task definition doesn't enable it
           if !task_definition.assess_in_portfolio_only

app/models/task.rb

@@ -7,6 +7,16 @@
   include ApplicationHelper
   include GradeHelper
 
+  PREREQUISITE_STATUS_LEVELS = {
+    ready_for_feedback: 1,
+    assess_in_portfolio: 1,
+    discuss: 2,
+    rediscuss: 2,
+    attention_required: 0,
+    demonstrate: 2,
+    complete: 3
+  }.freeze
+
   attr_accessor :discussion_confirmed_for_transition
 
   #
@@ -550,6 +560,29 @@
     [:complete, :discuss, :rediscuss, :demonstrate, :ready_for_feedback, :assess_in_portfolio].include? status
   end
 
+  def unmet_prerequisite_error
+    task_definition.task_prerequisites.each do |prerequisite|
+      prereq_td = prerequisite.prerequisite
+      minimum_status = TaskStatus.find(prerequisite.task_status_id)
+      prereq_task = project.task_for_task_definition(prereq_td)
+
+      next if prereq_task.ready_or_complete? &&
+              PREREQUISITE_STATUS_LEVELS[prereq_task.status] >= PREREQUISITE_STATUS_LEVELS[minimum_status.status_key]
+
+      verb = case minimum_status
+             when TaskStatus.complete then 'completed'
+             when TaskStatus.discuss then 'discussed'
+             when TaskStatus.rediscuss then 'rediscussed'
+             when TaskStatus.demonstrate then 'demonstrated'
+             when TaskStatus.ready_for_feedback then 'submitted'
+             end
+
+      return "Cannot submit this task until prerequisite '#{prereq_td.abbreviation}' has been #{verb}"
+    end
+
+    nil
+  end
+
   def submitted_status?
     [:working_on_it, :not_started, :fix_and_resubmit, :redo, :need_help].exclude? status
   end

test/api/tasks_api_test.rb

@@ -653,6 +653,45 @@ def test_cant_submit_until_prerequisites_submitted
     unit.destroy
   end
 
+  def test_cant_set_upload_free_task_ready_for_feedback_until_prerequisites_met
+    unit = FactoryBot.create(:unit, student_count: 1, task_count: 2)
+    prerequisite_definition, task_definition = unit.task_definitions.first(2)
+    prerequisite_definition.update!(target_grade: 0)
+    task_definition.update!(target_grade: 3, upload_requirements: [])
+    project = unit.active_projects.first
+    task = project.task_for_task_definition(task_definition)
+    prerequisite_task = project.task_for_task_definition(prerequisite_definition)
+    prerequisite = TaskPrerequisite.create!(
+      task_definition: task_definition,
+      prerequisite: prerequisite_definition,
+      task_status_id: TaskStatus.ready_for_feedback.id
+    )
+
+    add_auth_header_for(user: project.user)
+    path = "/api/projects/#{project.id}/task_def_id/#{task_definition.id}"
+
+    put path, { trigger: 'ready_for_feedback' }
+    assert_equal 409, last_response.status
+    assert_equal "Cannot submit this task until prerequisite '#{prerequisite_definition.abbreviation}' has been submitted",
+                 last_response_body['error']
+    assert_equal TaskStatus.not_started, task.reload.task_status
+
+    prerequisite.update!(task_status_id: TaskStatus.complete.id)
+    prerequisite_task.update!(task_status: TaskStatus.ready_for_feedback)
+
+    put path, { trigger: 'ready_for_feedback' }
+    assert_equal 409, last_response.status
+    assert_equal "Cannot submit this task until prerequisite '#{prerequisite_definition.abbreviation}' has been completed",
+                 last_response_body['error']
+    assert_equal TaskStatus.not_started, task.reload.task_status
+
+    prerequisite_task.update!(task_status: TaskStatus.complete)
+
+    put path, { trigger: 'ready_for_feedback' }
+    assert_equal 200, last_response.status
+    assert_equal TaskStatus.ready_for_feedback, task.reload.task_status
+  end
+
   def test_prerequisites_task_status
     # Create a unit and two task definitions
     unit = FactoryBot.create(:unit, student_count: 1, task_count: 10)