(PC-31244)[API] fix: handle skipped recredit for 16 in recredit

when a user used to register at 15 and finishes their credit activation
at 17, then the recredit 16 is to the deposit but the recredit 16 is not
created in the database. see commit e9b5f5e.

api/src/pcapi/core/finance/api.py

@@ -2924,7 +2924,24 @@ def _has_been_recredited(user: users_models.User) -> bool:
     if len(user.deposit.recredits) == 0:
         return False
 
-    return conf.RECREDIT_TYPE_AGE_MAPPING[user.age] in [recredit.recreditType for recredit in user.deposit.recredits]
+    has_been_recredited = conf.RECREDIT_TYPE_AGE_MAPPING[user.age] in [
+        recredit.recreditType for recredit in user.deposit.recredits
+    ]
+    if has_been_recredited:
+        return True
+
+    if user.age == 16:
+        # This condition handles the following edge case:
+        # - User started the activation workflow at 15 and finished it at 17.
+        #   This used to create a deposit holding the total amount from 15 to 17 years old without creating
+        #   the deposit for 16 years old in the database.
+        # - When trying to unlock their 18 years old deposit, we receive a new (correct) value for their age.
+        # - If this age is 16, no recredit happened (see 1st point) so we need a different check.
+        #
+        # This edge case is unlikely, but was introduced in e9b5f5e4.
+        return user.deposit.amount == sum(conf.RECREDIT_TYPE_AMOUNT_MAPPING.values())
+
+    return False
 
 
 def _get_known_age_at_deposit(user: users_models.User) -> int | None:

api/tests/core/finance/test_api.py

@@ -3964,6 +3964,16 @@ def test_cannot_be_recredited_when_recredit_was_already_given(self):
             can_be_recredited_for_16 = api._can_be_recredited(user)
             assert not can_be_recredited_for_16
 
+    def test_cannot_be_recredited_when_recredit_16_was_already_applied_but_not_created(self):
+        user = users_factories.BeneficiaryFactory(age=15)
+        factories.RecreditFactory(deposit=user.deposit, recreditType=models.RecreditType.RECREDIT_17)
+        user.deposit.amount = Decimal(20 + 30 + 30)
+
+        next_year = datetime.datetime.utcnow() + relativedelta(years=1)
+        with time_machine.travel(next_year):
+            can_be_recredited_for_16 = api._can_be_recredited(user)
+            assert not can_be_recredited_for_16
+
     def test_can_be_recredited_no_registration_datetime(self):
         with time_machine.travel("2020-05-02"):
             user = users_factories.UnderageBeneficiaryFactory(