Merge branch 'ek-follow-up-additional-datetime-jest-tests' into 'master'

Add additional test cases for a leap year

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/139171



Merged-by: Illya Klymov <xanf@xanf.me>
Approved-by: Deepika Guliani <dguliani@gitlab.com>
Co-authored-by: Ezekiel Kigbo <ekigbo@gitlab.com>

app/assets/javascripts/lib/utils/datetime/date_calculation_utility.js

@@ -401,6 +401,8 @@ export const nWeeksBefore = (date, numberOfWeeks, options) =>
 
 /**
  * Returns the date `n` years after the date provided.
+ * When Feb 29 is the specified date, the default behaviour is to return March 1.
+ * But to align with the equivalent rails code, moment JS and datefns we should return Feb 28 instead.
  *
  * @param {Date} date the initial date
  * @param {Number} numberOfYears number of years after
@@ -408,7 +410,16 @@ export const nWeeksBefore = (date, numberOfWeeks, options) =>
  */
 export const nYearsAfter = (date, numberOfYears) => {
   const clone = newDate(date);
-  clone.setFullYear(clone.getFullYear() + numberOfYears);
+  clone.setUTCMonth(clone.getUTCMonth());
+
+  // If the date we are calculating from is Feb 29, return the equivalent result for Feb 28
+  if (clone.getUTCMonth() === 1 && clone.getUTCDate() === 29) {
+    clone.setUTCDate(28);
+  } else {
+    clone.setUTCDate(clone.getUTCDate());
+  }
+
+  clone.setUTCFullYear(clone.getUTCFullYear() + numberOfYears);
   return clone;
 };
 

spec/frontend/lib/utils/datetime_utility_spec.js

@@ -785,11 +785,16 @@ describe('date addition/subtraction methods', () => {
     );
   });
 
+  // NOTE: 2024-02-29 is a leap day
   describe('nYearsAfter', () => {
     it.each`
       date            | numberOfYears | expected
       ${'2020-07-06'} | ${1}          | ${'2021-07-06'}
       ${'2020-07-06'} | ${15}         | ${'2035-07-06'}
+      ${'2024-03-02'} | ${1}          | ${'2025-03-02'}
+      ${'2024-03-01'} | ${1}          | ${'2025-03-01'}
+      ${'2024-02-29'} | ${1}          | ${'2025-02-28'}
+      ${'2024-02-28'} | ${1}          | ${'2025-02-28'}
     `(
       'returns $expected for "$numberOfYears year(s) after $date"',
       ({ date, numberOfYears, expected }) => {
@@ -805,6 +810,10 @@ describe('date addition/subtraction methods', () => {
       date            | numberOfYears | expected
       ${'2020-07-06'} | ${4}          | ${'2016-07-06'}
       ${'2020-07-06'} | ${1}          | ${'2019-07-06'}
+      ${'2024-03-02'} | ${1}          | ${'2023-03-02'}
+      ${'2024-03-01'} | ${1}          | ${'2023-03-01'}
+      ${'2024-02-29'} | ${1}          | ${'2023-02-28'}
+      ${'2024-02-28'} | ${1}          | ${'2023-02-28'}
     `(
       'returns $expected for "$numberOfYears year(s) before $date"',
       ({ date, numberOfYears, expected }) => {