Respect section start/end dates when outside of course dates

if a section has a start date before the course start date, or
and end date after a course end date, then dates in those
ranges should still be valid, even when 'Students can only
participate in the course between these dates' is not checked

closes LX-2085
flag=none

test plan:
- create a course with at least one section
- add a start date and end date to the course.
- add a start date to the section that is before the course
  start date.
- add an end date to the section that is after the course end
  date.
- do not check 'Students can only participate in the course
  between these dates'
- create a learning object and add dates to the section. Assign a date
  that is before the course start but not before the section start.
  The date should be valid.
- assign a date that is after course end but not after section end.
  the date should be valid.
- dates outside of the section's dates should still be invalid.
- change the start/end dates of the section so the start date is after
  course start date and the end date is before the course end date.
- ensure that you can still assign the section to dates within the
  course start/end dates even if they are outside the section dates.

Change-Id: I274c5d09f2f2831e403091d0cb53c51bd1dd1036
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/361783
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Drake Harper <drake.harper@instructure.com>
QA-Review: Drake Harper <drake.harper@instructure.com>
Product-Review: Sarah Gerard <sarah.gerard@instructure.com>

ui/shared/grading/DateValidator.js

@@ -236,16 +236,25 @@ export default class DateValidator {
   }
 
   getSectionRange(section) {
-    if (!section.override_course_and_term_dates) return this.dateRange
-
     const dateRange = {...this.dateRange}
-    if (section.start_at) {
+    const override_course_dates = section.override_course_and_term_dates
+    // if !override_course_dates, then use the earlier start date and the later end date
+    // if override_course_dates, then use the section start and end dates
+    if (
+      section.start_at &&
+      (override_course_dates ||
+        this._formatDatetime(section.start_at) < this._formatDatetime(dateRange.start_at.date))
+    ) {
       dateRange.start_at = {
         date: section.start_at,
         date_context: 'section',
       }
     }
-    if (section.end_at) {
+    if (
+      section.end_at &&
+      (override_course_dates ||
+        this._formatDatetime(section.end_at) > this._formatDatetime(dateRange.end_at.date))
+    ) {
       dateRange.end_at = {
         date: section.end_at,
         date_context: 'section',

ui/shared/grading/__tests__/DateValidator.spec.js

@@ -384,6 +384,12 @@ describe('section dates', () => {
           end_at: null,
           override_course_and_term_dates: null,
         },
+        {
+          id: 678,
+          start_at: '2020-03-01T00:00:00Z',
+          end_at: '2020-08-01T00:00:00Z',
+          override_course_and_term_dates: false,
+        },
       ],
     })
   })
@@ -492,4 +498,25 @@ describe('section dates', () => {
     const validator = makeIndividualValidator()
     expect(isValid(validator, data)).toBe(false)
   })
+
+  test('allows a lock date after the course end date if it is before the section end date', () => {
+    const data = generateData({
+      lock_at: '2020-07-01T00:00:00Z',
+      student_ids: null,
+      course_section_id: 678,
+    })
+    const validator = makeIndividualValidator({termEnd: '2020-06-01T00:00:00Z'})
+    expect(isValid(validator, data)).toBe(true)
+  })
+
+  test('allows an unlock date before the course start date if it is after the section start date', () => {
+    const data = generateData({
+      unlock_at: '2020-05-01T00:00:00Z',
+      due_at: '2020-06-01T00:00:00Z',
+      student_ids: null,
+      course_section_id: 678,
+    })
+    const validator = makeIndividualValidator({termStart: '2020-07-01T00:00:00Z'})
+    expect(isValid(validator, data)).toBe(true)
+  })
 })