fix: correct validation for rcm returns

(cherry picked from commit 3dc1070)

# Conflicts:
#	india_compliance/gst_india/overrides/test_transaction.py

india_compliance/gst_india/overrides/test_transaction.py

@@ -15,6 +15,7 @@
     update_child_qty_rate,
     update_gl_dict_with_regional_fields,
 )
+from erpnext.controllers.sales_and_purchase_return import make_return_doc
 from erpnext.controllers.taxes_and_totals import get_regional_round_off_accounts
 from erpnext.stock.doctype.delivery_note.delivery_note import make_sales_invoice
 from erpnext.stock.doctype.purchase_receipt.purchase_receipt import (
@@ -132,6 +133,74 @@ def test_transaction_with_rcm_to_unregistered_supplier(self):
             doc.taxes[0],
         )
 
+<<<<<<< HEAD
+=======
+    def test_rcm_transaction_with_returns(self):
+        "Make sure RCM is not applied on Sales Return"
+        if self.doctype not in [
+            "Delivery Note",
+            "Sales Invoice",
+            "Purchase Receipt",
+            "Purchase Invoice",
+        ]:
+            return
+
+        doc = create_transaction(
+            **self.transaction_details, is_reverse_charge=1, is_in_state_rcm=1
+        )
+        return_doc = make_return_doc(self.doctype, doc.name)
+        return_doc.save().submit()
+
+        self.assertEqual(return_doc.is_reverse_charge, 1)
+
+    def test_non_taxable_items_with_tax(self):
+        doc = create_transaction(
+            **self.transaction_details,
+            is_in_state=True,
+            item_tax_template="GST 28% - _TIRC",
+            do_not_submit=True,
+        )
+
+        for item in doc.items:
+            item.gst_treatment = "Nil-Rated"
+
+        self.assertRaisesRegex(
+            frappe.exceptions.ValidationError,
+            re.compile(r"^(Cannot charge GST on Non-Taxable Items.*)$"),
+            validate_item_tax_template,
+            doc,
+        )
+
+    def test_validate_item_tax_template(self):
+        item_tax_template = frappe.get_doc("Item Tax Template", "GST 28% - _TIRC")
+        tax_accounts = item_tax_template.get("taxes")
+
+        # Invalidate item tax template
+        item_tax_template.taxes = []
+        item_tax_template.flags.ignore_mandatory = True
+        item_tax_template.save()
+
+        doc = create_transaction(
+            **self.transaction_details,
+            is_in_state=True,
+            item_tax_template="GST 28% - _TIRC",
+            do_not_submit=True,
+        )
+
+        for tax in doc.taxes:
+            tax.rate = 0
+
+        self.assertRaisesRegex(
+            frappe.exceptions.ValidationError,
+            re.compile(r"^(No GST is being charged on Taxable Items.*)$"),
+            doc.save,
+        )
+
+        # Restore item tax template
+        item_tax_template.taxes = tax_accounts
+        item_tax_template.save()
+
+>>>>>>> 3dc10704 (fix: correct validation for rcm returns)
     def test_transaction_for_items_with_duplicate_taxes(self):
         # Should not allow same item in invoice with multiple taxes
         doc = create_transaction(**self.transaction_details, do_not_save=True)

india_compliance/gst_india/overrides/transaction.py

@@ -1067,46 +1067,49 @@ def validate_reverse_charge_transaction(doc):
     if not doc.get("is_reverse_charge"):
         return
 
+    is_return = doc.get("is_return", False)
+
+    def _throw_tax_error(is_positive, tax, comment_suffix=""):
+        expected = "positive" if is_positive else "negative"
+        if is_return:
+            expected = "negative" if is_positive else "positive"
+
+        frappe.throw(
+            _("Row #{0}: Tax amount should be {1} for GST Account {2}{3}").format(
+                tax.idx, expected, tax.account_head, comment_suffix
+            )
+        )
+
     for tax in doc.get("taxes"):
-        if not tax.gst_tax_type:
+        if not tax.gst_tax_type or not tax.tax_amount:
             continue
 
+        tax_amount = tax.base_tax_amount_after_discount_amount
+        if is_return:
+            tax_amount = -tax_amount
+
+        is_positive = tax_amount > 0
+
         if "rcm" not in tax.gst_tax_type:
-            # NON RCM should be positive
-            if (
-                tax.get("add_deduct_tax", "Add") != "Add"
-                or tax.base_tax_amount_after_discount_amount < 0
-            ):
-                frappe.throw(
-                    _(
-                        "Row #{0}: Tax amount should be positive for GST Account {1}"
-                    ).format(tax.idx, tax.account_head)
-                )
+            # NON RCM logic
+            if tax.get("add_deduct_tax", "Add") != "Add" or not is_positive:
+                _throw_tax_error(True, tax)
 
-            base_gst_tax += tax.base_tax_amount_after_discount_amount
+            base_gst_tax += tax_amount
 
         elif "rcm" in tax.gst_tax_type:
-            # Using Deduct for RCM
+            # RCM logic
             if tax.get("add_deduct_tax") == "Deduct":
-                if tax.base_tax_amount_after_discount_amount < 0:
-                    frappe.throw(
-                        _(
-                            "Row #{0}: Tax amount should be positive for GST Account {1}"
-                            " as you are Deducting Tax"
-                        ).format(tax.idx, tax.account_head)
-                    )
+                if not is_positive:
+                    _throw_tax_error(True, tax, " as you are Deducting Tax")
 
-                base_reverse_charge_booked -= tax.base_tax_amount_after_discount_amount
+                base_reverse_charge_booked -= tax_amount
 
             else:
-                if tax.base_tax_amount_after_discount_amount > 0:
-                    frappe.throw(
-                        _(
-                            "Row #{0}: Tax amount should be negative for GST Account {1}"
-                        ).format(tax.idx, tax.account_head)
-                    )
+                if is_positive:
+                    _throw_tax_error(False, tax)
 
-                base_reverse_charge_booked += tax.base_tax_amount_after_discount_amount
+                base_reverse_charge_booked += tax_amount
 
     condition = flt(base_gst_tax + base_reverse_charge_booked, 2) == 0