fix: earned leaves not allocated if assignment is created on month-end based on Leave Period

[ruchamahabal]

Background

1. On the creation of a Leave Policy Assignment for Earned Leaves, allocation of leaves happens in 2 stages:
   • If this assignment is done in the latter months of the leave period, it allocates leaves for past months.
   • then, a daily background job runs for allocating "earned" leaves at the end of every month (in case of monthly frequency)
2. For eg: the leave period starts from Jan 2022 and you create an assignment in Feb 2022 then it will allocate leave for Jan and then allocate leaves for Feb onwards during month-end as per your frequency set in the leave type

Problem

1. If you create an assignment on month-end, say 31st Jan 2022, and the policy period starts from 1st Jan 2022, then 1 leave should be allocated since it is the last day of the month.
2. But this does not happen because as per the current logic, the month has not "passed".
3. Also, the daily background job would run at 12:00 am on 31st Jan 2022, but if you create an assignment after it, then the job is already over and it will next run on 1st Feb 2022, but this is not the last day of the month, so leave is never allocated for Jan.

Steps to Replicate

• Leave Type configuration

  

• Leave Policy:

  

• Leave Policy Assignment created for Jan 2022-Dec 2022 on 31st Jan 2022

  

• 0 Total Leaves Allocated in Leave Allocation although Jan has passed (it is 31st)

  

Fix

1. If the assignment is created on the last day of the month within the leave period, consider it in "past months" because the employee should already "earn" this leave.
2. Add a check in the background job allocation to determine if the leave is not already allocated, to avoid duplication.
3. Add tests for both cases.

1 Leave allocated for Jan on policy assignment creation. Check Total Leaves Allocated

• Handle carry-forwarded leaves while checking if leaves are already allocated

[codecov]

Codecov Report

Merging #29650 (b71283a) into develop (bb105a3) will increase coverage by 0.20%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop   #29650      +/-   ##
===========================================
+ Coverage    58.88%   59.09%   +0.20%     
===========================================
  Files         1112     1112              
  Lines        69467    69488      +21     
===========================================
+ Hits         40907    41061     +154     
+ Misses       28560    28427     -133     

Impacted Files	Coverage Δ
...leave_policy_assignment/leave_policy_assignment.py	87.71% <100.00%> (+1.87%)	⬆️
erpnext/hr/utils.py	76.40% <100.00%> (+1.20%)	⬆️
...rpnext/stock/report/stock_balance/stock_balance.py	79.16% <0.00%> (-0.60%)	⬇️
erpnext/selling/doctype/quotation/quotation.py	49.18% <0.00%> (-0.55%)	⬇️
erpnext/stock/doctype/serial_no/serial_no.py	80.97% <0.00%> (-0.26%)	⬇️
erpnext/stock/doctype/item/item.py	83.04% <0.00%> (-0.18%)	⬇️
erpnext/regional/india/e_invoice/utils.py	42.79% <0.00%> (ø)
...stock/doctype/purchase_receipt/purchase_receipt.py	91.34% <0.00%> (+0.25%)	⬆️
erpnext/projects/doctype/project/project.py	54.89% <0.00%> (+0.34%)	⬆️
erpnext/accounts/report/financial_statements.py	35.63% <0.00%> (+0.38%)	⬆️
... and 24 more

[ruchamahabal]

@Mergifyio backport version-13-hotfix

[mergify]

backport version-13-hotfix

✅ Backports have been created

• #29708 fix: earned leaves not allocated if assignment is created on month-end based on Leave Policy (backport #29650) has been created for branch version-13-hotfix