hide assignment statistics to students when < 5 submissions

if there's less than 5 submissions a student may be able to look at the box and
whisker plot + the high/mean/low stats and determine other students grades.

fixes #11458

test plan:
- create an assignment, and grade < 5 students.
- as one of the students, go to the grades summary page, click "all details"
- you should not see a box and whisker plot or a tooltip with high/mean/low
  data
- now grade more students, so that > 5 have grades
- as a student, go back, and now the graph + tooltip should show

Change-Id: Ib76164dc9ca9cf7c8563de427b27f52e5081447a
Reviewed-on: https://gerrit.instructure.com/14757
Reviewed-by: Stanley Stuart <stanley@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>

Author: simonista

app/views/gradebooks/grade_summary.html.erb

@@ -120,6 +120,7 @@
   <%
      submission = @submissions.find {|s| s.assignment_id == assignment.id }
      submission_unread = (submission.present? ? @unread_submission_ids.include?(submission.id) : false)
+     assignment_submissions = @all_submissions.select { |s| s.assignment_id == assignment.id }
      visible_rubric_assessments = []
      visible_rubric_assessments = submission.rubric_assessments.select{|a| a.grants_rights?(@current_user, :read)[:read]}.sort_by{|a| [a.assessment_type == 'grading' ? '0' : '1', a.assessor_name] } if submission && !assignment.muted?
   %>
@@ -251,8 +252,9 @@
   <tr id="grade_info_<%= assignment.id %>" aria-expanded="false" role="region" class="comments <%= 'assignment_graded' if submission && submission.grade && !assignment.muted? %>" style="display: none;">
     <% if !assignment.special_class && (has_comments || has_scoring_details) %>
       <td colspan="5" style="padding-bottom: 20px;">
-        <% if assignment && assignment.points_possible && assignment.points_possible > 0 && !assignment.muted? %>
-        <% high, low, mean = assignment.grade_distribution(@all_submissions.select { |s| s.assignment_id == assignment.id }) %>
+        <% can_view_distribution = can_do(@context, @current_user, :read_as_admin) || assignment_submissions.length >= 5 %>
+        <% if assignment && assignment.points_possible && assignment.points_possible > 0 && !assignment.muted? && can_view_distribution %>
+        <% high, low, mean = assignment.grade_distribution(assignment_submissions) %>
         <% title = "" %>
         <% title += " " + before_label(:mean_score, "Mean") + " " + (mean.round(1) rescue 0).to_s %>
         <% title += " " + before_label(:high_score, "High") + " " + high.to_s unless assignment && assignment.hide_max_scores_for_assignments %>

spec/selenium/grades_spec.rb

@@ -114,11 +114,11 @@
   context "as a student" do
     before(:each) do
       user_session(@student_1)
-      get "/courses/#{@course.id}/grades"
-      @grade_tbody = f('#grades_summary > tbody')
     end
 
     it "should allow student to test modifying grades" do
+      get "/courses/#{@course.id}/grades"
+
       # just one ajax request
       Assignment.expects(:find_or_create_submission).once.returns(@submission)
 
@@ -142,6 +142,8 @@
     end
 
     it "should display rubric on assignment" do
+      get "/courses/#{@course.id}/grades"
+
       #click rubric
       f("#submission_#{@first_assignment.id} .toggle_rubric_assessments_link").click
       wait_for_animations
@@ -153,6 +155,8 @@
     end
 
     it "should not display rubric on muted assignment" do
+      get "/courses/#{@course.id}/grades"
+
       @first_assignment.muted = true
       @first_assignment.save!
       get "/courses/#{@course.id}/grades"
@@ -161,6 +165,8 @@
     end
 
     it "should not display letter grade score on muted assignment" do
+      get "/courses/#{@course.id}/grades"
+
       @another_assignment = assignment_model({
                                                  :course => @course,
                                                  :title => 'another assignment',
@@ -178,6 +184,14 @@
     end
 
     it "should display teacher comment and assignment statistics" do
+      # get up to a point where statistics can be shown
+      5.times do
+        s = student_in_course(:active_all => true).user
+        @first_assignment.grade_student(s, :grade => 4)
+      end
+
+      get "/courses/#{@course.id}/grades"
+
       #check comment
       f('.toggle_comments_link img').click
       comment_row = f('#grades_summary tr.comments')
@@ -186,11 +200,16 @@
       #check tooltip text statistics
       driver.execute_script('$("#grades_summary tr.comments span.tooltip_text").css("visibility", "visible");')
       statistics_text = comment_row.find_element(:css, 'span.tooltip_text').text
-      statistics_text.include?("#{before_label(:mean_score, "Mean")} 3.5").should be_true
+      statistics_text.include?("Mean:").should be_true
       statistics_text.include?('High: 4').should be_true
       statistics_text.include?('Low: 3').should be_true
     end
 
+    it "should not show assignment statistics on assignments with less than 5 submissions" do
+      get "/courses/#{@course.id}/grades"
+      f("#grade_info_#{@first_assignment.id} .tooltip").should be_nil
+    end
+
     it "should show rubric even if there are no comments" do
       @third_association = @rubric.associate_with(@third_assignment, @course, :purpose => 'grading')
       @third_submission = @third_assignment.submissions.create!(:user => @student_1) # unsubmitted submission :/

spec/views/gradebooks/grade_summary.html.erb_spec.rb

@@ -28,6 +28,7 @@
     assigns[:assignments] = [a]
     assigns[:submissions] = []
     assigns[:courses_with_grades] = []
+    assigns[:all_submissions] = []
     render "gradebooks/grade_summary"
     response.should_not be_nil
   end
@@ -41,6 +42,7 @@
     assigns[:assignments] = [a]
     assigns[:submissions] = []
     assigns[:courses_with_grades] = []
+    assigns[:all_submissions] = []
     render "gradebooks/grade_summary"
     response.should_not be_nil
     page = Nokogiri('<document>' + response.body + '</document>')
@@ -58,6 +60,7 @@
     assigns[:assignments] = [a]
     assigns[:submissions] = []
     assigns[:courses_with_grades] = []
+    assigns[:all_submissions] = []
     render "gradebooks/grade_summary"
     response.should_not be_nil
     response.body.should_not match /Click any score/