Round pointsPossible variable substitution if a whole number

Fixes PLAT-1498

Test Plan:

With the test tool, create a new assignment with
100 points possible. The value posted to the tool 
for the points_possible variable expansion should
be "100" not "100.0". A assignment with 100.5 points
possible should post as "100.5".

Change-Id: I5eaf29817a7a71626f1407cda4c75a3853c816d3
Reviewed-on: https://gerrit.instructure.com/79297
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Reviewed-by: Brad Humphrey <brad@instructure.com>
Tested-by: Jenkins
QA-Review: August Thornton <august@instructure.com>
Product-Review: Karl Lloyd <karl@instructure.com>

Author: mcwqy9

lib/lti/variable_expander.rb

@@ -401,7 +401,7 @@ def expand_variables!(var_hash)
                        ASSIGNMENT_GUARD
 
     register_expansion 'Canvas.assignment.pointsPossible', [],
-                       -> { @assignment.points_possible },
+                       -> { TextHelper.round_if_whole(@assignment.points_possible) },
                        ASSIGNMENT_GUARD
     # @deprecated in favor of ISO8601
     register_expansion 'Canvas.assignment.unlockAt', [],

spec/lib/lti/variable_expander_spec.rb

@@ -376,11 +376,27 @@ module Lti
           expect(exp_hash[:test]).to eq 'Buy as many ducks as you can'
         end
 
-        it 'has substitution for $Canvas.assignment.pointsPossible' do
-          assignment.stubs(:points_possible).returns(10)
-          exp_hash = {test: '$Canvas.assignment.pointsPossible'}
-          subject.expand_variables!(exp_hash)
-          expect(exp_hash[:test]).to eq 10
+        describe "$Canvas.assignment.pointsPossible" do
+          it 'has substitution for $Canvas.assignment.pointsPossible' do
+            assignment.stubs(:points_possible).returns(10.0)
+            exp_hash = {test: '$Canvas.assignment.pointsPossible'}
+            subject.expand_variables!(exp_hash)
+            expect(exp_hash[:test]).to eq 10
+          end
+
+          it 'does not round if not whole' do
+            assignment.stubs(:points_possible).returns(9.5)
+            exp_hash = {test: '$Canvas.assignment.pointsPossible'}
+            subject.expand_variables!(exp_hash)
+            expect(exp_hash[:test].to_s).to eq "9.5"
+          end
+
+          it 'rounds if whole' do
+            assignment.stubs(:points_possible).returns(9.0)
+            exp_hash = {test: '$Canvas.assignment.pointsPossible'}
+            subject.expand_variables!(exp_hash)
+            expect(exp_hash[:test].to_s).to eq "9"
+          end
         end
 
         it 'has substitution for $Canvas.assignment.unlockAt' do

spec/models/lti/lti_integration_spec.rb

@@ -418,7 +418,7 @@ def tool_setup(for_student=true)
       expect(hash['ext_ims_lis_basic_outcome_url']).to eq "/my/other/test/url"
       expect(hash['ext_outcome_data_values_accepted']).to eq 'url,text'
       expect(hash['custom_canvas_assignment_title']).to eq @assignment.title
-      expect(hash['custom_canvas_assignment_points_possible']).to eq @assignment.points_possible.to_s
+      expect(hash['custom_canvas_assignment_points_possible']).to eq "5"
       expect(hash['custom_canvas_assignment_id']).to eq @assignment.id.to_s
     end
 
@@ -429,7 +429,7 @@ def tool_setup(for_student=true)
       expect(hash['ext_ims_lis_basic_outcome_url']).to eq "/my/other/test/url"
       expect(hash['ext_outcome_data_values_accepted']).to eq 'url,text'
       expect(hash['custom_canvas_assignment_title']).to eq @assignment.title
-      expect(hash['custom_canvas_assignment_points_possible']).to eq @assignment.points_possible.to_s
+      expect(hash['custom_canvas_assignment_points_possible']).to eq "5"
     end
   end