[ADD] account_exchange_difference_invoice: add tests

test_01 - Verifies exchange entries are auto-created when invoices are paid with different rates
test_02 - Checks exchange_info computed field shows which invoices caused the difference
test_03 - Tests wizard opens and groups exchange entries by partner
test_04 - Validates full workflow: wizard creates debit/credit notes and marks entries as processed
test_05 - Ensures reversal entries are posted and reconciled correctly
test_06 - Validates wizard raises error when no entries are provided
test_07 - Confirms wizard prevents processing entries from multiple companies
test_08 - Tests domain filter returns only unprocessed exchange entries
test_09 - Verifies exchange difference action opens with correct filters
test_10 - Tests wizard with manual fiscal position override
test_11 - Validates reversal entries are created with proper links
test_12 - Confirms zero-balance partners show warning and skip invoice creation
test_13 - Verifies messages are posted to related payment records
test_14 - Validates demo data creates correct currency rates for testing

Author: cav-adhoc

account_exchange_difference_invoice/tests/__init__.py

@@ -0,0 +1 @@
+from . import test_exchange_difference_invoice