invalid drop rules input

fixes CNVS-9210

test plan:
 - with draft state on, in the assignments index page
 - attempt to input 'tree' or 'plant' or anything really, into
   both the drop lowest scores and drop highest scores input boxes
   in the edit assignment group dialog
 - click save
 - it should ask you to use a number and it should not close the
   dialog or save the rules

Change-Id: I72ecfb3181e685d6c619af4ba0741838018a87ed
Reviewed-on: https://gerrit.instructure.com/25975
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Simon Williams <simon@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: David Scoville <davids@instructure.com>

app/coffeescripts/views/assignments/CreateGroupView.coffee

@@ -1,4 +1,5 @@
 define [
+  'i18n!assignments'
   'underscore'
   'compiled/models/AssignmentGroup'
   'compiled/collections/NeverDropCollection'
@@ -6,7 +7,7 @@ define [
   'compiled/views/DialogFormView'
   'jst/assignments/CreateGroup'
   'jst/EmptyDialogFormWrapper'
-], ( _, AssignmentGroup, NeverDropCollection, NeverDropCollectionView, DialogFormView, template, wrapper) ->
+], (I18n, _, AssignmentGroup, NeverDropCollection, NeverDropCollectionView, DialogFormView, template, wrapper) ->
 
   class CreateGroupView extends DialogFormView
     defaults:
@@ -27,6 +28,11 @@ define [
     @optionProperty 'assignmentGroup'
     @optionProperty 'course'
 
+    messages:
+      non_number: I18n.t('non_number', 'You must use a number')
+      positive_number: I18n.t('positive_number', 'You must use a positive number')
+      max_number: I18n.t('higher_than_max', 'You cannot use a number greater than the number of assignments')
+
     initialize: ->
       super
       #@assignmentGroup will be defined when editing
@@ -50,6 +56,24 @@ define [
       delete data.rules.never_drop if data.rules.never_drop?.length == 0
       data
 
+    validateFormData: (data) ->
+      max = null
+      if @assignmentGroup
+        as = @assignmentGroup.get('assignments')
+        max = as.size() if as?
+      errors = {}
+      _.each data.rules, (value, name) =>
+        val = parseInt(value)
+        field = "rules[#{name}]"
+        if isNaN(val)
+          errors[field] = [{type: 'number', message: @messages.non_number}]
+        if val < 0
+          errors[field] = [{type: 'positive_number', message: @messages.positive_number}]
+        if max?
+          if val > max
+            errors[field] = [{type: 'maximum', message: @messages.max_number}]
+      errors
+
     showWeight: ->
       course = @course or @model.collection?.course
       course?.get('apply_assignment_group_weights')

app/views/jst/assignments/CreateGroup.handlebars

@@ -39,7 +39,7 @@
         </label>
         <div class="controls">
           <input
-            type="text"
+            type="number"
             id="ag_{{label_id}}_drop_lowest"
             class="span1 field"
             name="rules[drop_lowest]"
@@ -53,7 +53,7 @@
         </label>
         <div class="controls">
           <input
-            type="text"
+            type="number"
             id="ag_{{label_id}}_drop_highest"
             class="span1 field"
             name="rules[drop_highest]"

spec/coffeescripts/views/assignments/CreateGroupViewSpec.coffee

@@ -0,0 +1,49 @@
+define [
+  'underscore'
+  'Backbone'
+  'compiled/collections/AssignmentGroupCollection'
+  'compiled/models/AssignmentGroup'
+  'compiled/models/Assignment'
+  'compiled/views/assignments/CreateGroupView'
+  'jquery'
+  'helpers/jquery.simulate'
+  'helpers/fakeENV'
+], (_, Backbone, AssignmentGroupCollection, AssignmentGroup, Assignment, CreateGroupView, $) ->
+
+  group = ->
+    new AssignmentGroup
+      assignments: [new Assignment, new Assignment]
+
+  assignmentGroups = ->
+    @groups = new AssignmentGroupCollection([group(), group()])
+
+  createView = ->
+    view = new CreateGroupView
+      assignmentGroups: assignmentGroups()
+      assignmentGroup: @groups.first()
+
+  module 'CreateGroupView'
+
+  test 'it should only allow positive numbers for drop rules', ->
+    view = createView()
+    data =
+      rules:
+        drop_lowest: "tree"
+        drop_highest: -1
+
+    errors = view.validateFormData(data)
+    ok errors
+    equal _.keys(errors).length, 2
+
+
+  test 'it should only allow less than the number of assignments for drop rules', ->
+    view = createView()
+    assignments = view.assignmentGroup.get('assignments')
+
+    data =
+      rules:
+        drop_highest: 5
+
+    errors = view.validateFormData(data)
+    ok errors
+    equal _.keys(errors).length, 1

spec/selenium/assignments_group_spec.rb

@@ -148,6 +148,7 @@ describe "assignment groups" do
 
       course_with_teacher_logged_in(:active_all => true)
       @assignment_group = @course.assignment_groups.create!(:name => "Test Group")
+      @course.assignments.create(:name => "test", :assignment_group => @assignment_group)
 
       get "/courses/#{@course.id}/assignments"
       wait_for_ajaximations