End plan on a friday if course ends on a skipped weekend

closes LS-3074
flag=course_paces

test plan:
  - Create a course with course pace enabled
  - In settings set course start on April 4, 2022 and
    end on Monday May 2, 2022. This effectively ends
    the course at fancy midnight Sunday May 1.
  - Create a module with 3 assignments
  - go to the course pacing page
  - in the course pace,  skip weekends.
  - Set the 3 durations to 1, 2, 30 so it has to compress
  > expect the last assignment's due date to be the Friday
    before the pace end date

Change-Id: I6229df7c9894c035774b33c39fff69e6833e6ab1
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/288705
Reviewed-by: Robin Kuss <rkuss@instructure.com>
QA-Review: Robin Kuss <rkuss@instructure.com>
Product-Review: Ed Schiebel <eschiebel@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>

lib/course_pace_hard_end_date_compressor.rb

@@ -36,6 +36,16 @@ class CoursePaceHardEndDateCompressor
 
     start_date_of_item_group = start_date || enrollment&.start_at || course_pace.start_date
     end_date = course_pace.end_date || course_pace.course.end_at&.to_date || course_pace.course.enrollment_term&.end_at&.to_date
+    # when due dates run over and the end date is on a weekend, the adjustment to due dates
+    # is off by a day. Pull the end_date back to the previous friday.
+    if end_date && course_pace.exclude_weekends
+      wday = end_date.wday
+      if wday == 0 # sunday
+        end_date -= 2.days
+      elsif wday == 6 # saturday
+        end_date -= 1.day
+      end
+    end
     due_dates = CoursePaceDueDatesCalculator.new(course_pace).get_due_dates(items, enrollment, start_date: start_date_of_item_group)
 
     if compress_items_after

spec/lib/course_pace_hard_end_date_compressor_spec.rb

@@ -82,6 +82,12 @@ describe CoursePaceHardEndDateCompressor do
           compressed = CoursePaceHardEndDateCompressor.compress(@course_pace, @course_pace.course_pace_module_items)
           expect(compressed.pluck(:duration)).to eq([1, 1, 2])
         end
+
+        it "considers the end date the previous Friday if it falls on the weekend" do
+          @course.update(conclude_at: "2022-01-02") # Sunday
+          compressed = CoursePaceHardEndDateCompressor.compress(@course_pace, @course_pace.course_pace_module_items)
+          expect(compressed.pluck(:duration)).to eq([1, 1, 2])
+        end
       end
     end