test: marginal min order qty overage raises a toast

A minimum order qty defined in stock UOM often has no exact
representation in the purchase UOM, so the smallest valid order slightly
exceeds the minimum. Surface that overage on the Purchase Order with a
toast on first save when an item's ordered stock qty is above its
minimum by less than one purchase-UOM step, so the buyer sees the
marginal increase before sending the order. Sub-precision dust stays
silent.

erpnext/buying/doctype/purchase_order/purchase_order.py

@@ -319,6 +319,38 @@ class PurchaseOrder(BuyingController):
 					).format(item_code, flt(qty, precision), itemwise_min_order_qty.get(item_code))
 				)
 
+		self.warn_marginal_min_order_qty(itemwise_qty, itemwise_min_order_qty)
+
+	def warn_marginal_min_order_qty(self, itemwise_qty, itemwise_min_order_qty):
+		"""Toast when an item's ordered qty exceeds its minimum only by purchase UOM rounding."""
+		if not self.is_new():
+			return
+
+		precision = self.items[0].precision("stock_qty")
+		itemwise_step = frappe._dict()
+		itemwise_stock_uom = frappe._dict()
+		for d in self.get("items"):
+			step = 10 ** -d.precision("qty") * flt(d.conversion_factor)
+			itemwise_step[d.item_code] = max(itemwise_step.get(d.item_code, 0), step)
+			itemwise_stock_uom[d.item_code] = d.stock_uom
+
+		for item_code, qty in itemwise_qty.items():
+			min_order_qty = flt(itemwise_min_order_qty.get(item_code))
+			overage = flt(qty) - min_order_qty
+			if min_order_qty and flt(overage, precision) > 0 and overage < itemwise_step[item_code]:
+				frappe.toast(
+					_(
+						"Item {0}: Ordered qty {1} {2} exceeds the minimum order qty {3} {2} by {4} {2} due to purchase UOM rounding."
+					).format(
+						item_code,
+						flt(qty, precision),
+						itemwise_stock_uom[item_code],
+						min_order_qty,
+						flt(overage, precision),
+					),
+					indicator="orange",
+				)
+
 	def get_schedule_dates(self):
 		for d in self.get("items"):
 			if d.material_request_item and not d.schedule_date:

erpnext/buying/doctype/purchase_order/test_purchase_order.py

@@ -724,6 +724,30 @@ class TestPurchaseOrder(ERPNextTestSuite):
 		below_minimum.items[0].conversion_factor = 0.6
 		self.assertRaises(frappe.ValidationError, below_minimum.insert)
 
+	def test_marginal_min_order_qty_overage_toast(self):
+		original_precision = frappe.db.get_default("float_precision")
+		frappe.db.set_default("float_precision", "3")
+		self.addCleanup(frappe.db.set_default, "float_precision", original_precision)
+
+		if not frappe.db.exists("UOM", "Gram"):
+			frappe.get_doc({"doctype": "UOM", "uom_name": "Gram"}).insert()
+
+		item_doc = make_item(properties={"min_order_qty": 50000, "stock_uom": "Gram"})
+		item_doc.append("uoms", {"uom": "Pound", "conversion_factor": 453.592292197})
+		item_doc.save()
+		item = item_doc.name
+
+		def insert_po(qty):
+			po = create_purchase_order(item_code=item, qty=qty, do_not_save=1)
+			po.items[0].uom = "Pound"
+			po.items[0].conversion_factor = 453.592292197
+			frappe.clear_messages()
+			po.insert()
+			return any("minimum order qty" in d.get("message", "") for d in frappe.get_message_log())
+
+		self.assertTrue(insert_po(110.232))
+		self.assertFalse(insert_po(150))
+
 	def test_uom_integer_check_tolerates_conversion_dust(self):
 		from erpnext.utilities.transaction_base import UOMMustBeIntegerError
 

erpnext/manufacturing/doctype/production_plan/services/material_request.py

@@ -11,6 +11,7 @@ existing imports of ``...services.material_planning`` keep working through here.
 import copy
 import json
 from collections import defaultdict
+from decimal import ROUND_CEILING, Decimal
 
 import frappe
 from frappe import _, msgprint
@@ -493,8 +494,16 @@ def get_material_request_items(
 	)
 	item_group_defaults = get_item_group_defaults(row.item_code, company)
 	conversion_factor = _mr_purchase_conversion_factor(row)
+	min_order_qty = flt(row.get("min_order_qty")) if doc.get("consider_minimum_order_qty") else 0
 	return _material_request_item_row(
-		row, sales_order, target_warehouse, bin_dict, required_qty, conversion_factor, item_group_defaults
+		row,
+		sales_order,
+		target_warehouse,
+		bin_dict,
+		required_qty,
+		conversion_factor,
+		item_group_defaults,
+		min_order_qty,
 	)
 
 
@@ -539,6 +548,18 @@ def _adjust_required_qty_for_uom(row, required_qty):
 	return required_qty
 
 
+def _quantity_in_purchase_uom(required_qty, conversion_factor, min_order_qty=0):
+	"""Convert to purchase UOM; a binding minimum order qty takes the smallest
+	representable quantity whose stock equivalent still meets it."""
+	precision = frappe.get_precision("Material Request Plan Item", "quantity")
+	quantity = flt(required_qty / conversion_factor, precision)
+	if min_order_qty and quantity * conversion_factor < min_order_qty <= required_qty:
+		grid = Decimal(10) ** -precision
+		exact = Decimal(str(min_order_qty)) / Decimal(str(conversion_factor))
+		quantity = flt(exact.quantize(grid, rounding=ROUND_CEILING))
+	return quantity
+
+
 def _mr_purchase_conversion_factor(row):
 	item_details = frappe.get_cached_value("Item", row.item_code, ["purchase_uom", "stock_uom"], as_dict=1)
 	if (
@@ -551,7 +572,14 @@ def _mr_purchase_conversion_factor(row):
 
 
 def _material_request_item_row(
-	row, sales_order, warehouse, bin_dict, required_qty, conversion_factor, item_group_defaults
+	row,
+	sales_order,
+	warehouse,
+	bin_dict,
+	required_qty,
+	conversion_factor,
+	item_group_defaults,
+	min_order_qty=0,
 ):
 	warehouse = (
 		warehouse
@@ -559,11 +587,10 @@ def _material_request_item_row(
 		or row.get("default_warehouse")
 		or item_group_defaults.get("default_warehouse")
 	)
-	precision = frappe.get_precision("Material Request Plan Item", "quantity")
 	return {
 		"item_code": row.item_code,
 		"item_name": row.item_name,
-		"quantity": flt(required_qty / conversion_factor, precision),
+		"quantity": _quantity_in_purchase_uom(required_qty, conversion_factor, min_order_qty),
 		"conversion_factor": conversion_factor,
 		"required_bom_qty": row.get("qty"),
 		"stock_uom": row.get("stock_uom"),
@@ -640,7 +667,8 @@ def _add_remaining_purchase_request(item, new_mr_items, required_qty, consider_m
 	if frappe.db.get_value("UOM", purchase_uom, "must_be_whole_number"):
 		required_qty = ceil(required_qty)
 
-	item["quantity"] = flt(required_qty / item.get("conversion_factor"), precision)
+	min_order_qty = flt(item.get("min_order_qty")) if consider_minimum_order_qty else 0
+	item["quantity"] = _quantity_in_purchase_uom(required_qty, item.get("conversion_factor"), min_order_qty)
 	new_mr_items.append(item)
 
 

erpnext/manufacturing/doctype/production_plan/test_production_plan.py

@@ -2384,6 +2384,73 @@ class TestProductionPlan(ERPNextTestSuite):
 		self.assertEqual(items_by_type["Material Transfer"].get("quantity"), 7.0)
 		self.assertEqual(items_by_type["Purchase"].get("quantity"), 1000.0)
 
+	def test_min_order_qty_conversion_takes_grid_ceiling(self):
+		from erpnext.manufacturing.doctype.production_plan.services.material_request import (
+			_quantity_in_purchase_uom,
+		)
+
+		original_precision = frappe.db.get_default("float_precision")
+		frappe.db.set_default("float_precision", "3")
+		self.addCleanup(frappe.db.set_default, "float_precision", original_precision)
+
+		self.assertEqual(_quantity_in_purchase_uom(50000, 453.592292197, 50000), 110.232)
+		self.assertEqual(_quantity_in_purchase_uom(2000, 0.453592, 2000), 4409.249)
+		self.assertEqual(_quantity_in_purchase_uom(10, 0.5, 10), 20.0)
+		self.assertEqual(_quantity_in_purchase_uom(50000, 453.592292197), 110.231)
+
+	def test_min_order_qty_grid_ceiling_in_plan_items(self):
+		original_precision = frappe.db.get_default("float_precision")
+		frappe.db.set_default("float_precision", "3")
+		self.addCleanup(frappe.db.set_default, "float_precision", original_precision)
+
+		conversion_factor = 453.592292197
+		fg_item = make_item(properties={"is_stock_item": 1}).name
+		rm_item = make_item(
+			properties={"is_stock_item": 1, "min_order_qty": 50000, "purchase_uom": "_Test UOM 1"},
+			uoms=[{"uom": "_Test UOM 1", "conversion_factor": conversion_factor}],
+		).name
+
+		make_bom(item=fg_item, raw_materials=[rm_item], source_warehouse="_Test Warehouse - _TC")
+
+		pln = create_production_plan(item_code=fg_item, planned_qty=1, do_not_submit=1)
+		pln.consider_minimum_order_qty = 1
+		mr_items = get_items_for_material_requests(pln.as_dict())
+
+		self.assertEqual(mr_items[0].get("quantity"), 110.232)
+		self.assertGreaterEqual(mr_items[0].get("quantity") * conversion_factor, 50000)
+
+	def test_min_order_qty_grid_ceiling_from_other_locations(self):
+		from erpnext.stock.doctype.warehouse.test_warehouse import create_warehouse
+
+		original_precision = frappe.db.get_default("float_precision")
+		frappe.db.set_default("float_precision", "3")
+		self.addCleanup(frappe.db.set_default, "float_precision", original_precision)
+
+		conversion_factor = 453.592292197
+		fg_item = make_item(properties={"is_stock_item": 1}).name
+		rm_item = make_item(
+			properties={"is_stock_item": 1, "min_order_qty": 50000, "purchase_uom": "_Test UOM 1"},
+			uoms=[{"uom": "_Test UOM 1", "conversion_factor": conversion_factor}],
+		).name
+
+		rm_warehouse = create_warehouse("MOQ Ceiling RM Warehouse", company="_Test Company")
+		source_warehouse = create_warehouse("MOQ Ceiling Source Warehouse", company="_Test Company")
+		make_stock_entry(item_code=rm_item, qty=4, rate=100, target=source_warehouse)
+
+		make_bom(item=fg_item, raw_materials=[rm_item], source_warehouse="_Test Warehouse - _TC")
+
+		pln = create_production_plan(item_code=fg_item, planned_qty=10, do_not_submit=1)
+		pln.for_warehouse = rm_warehouse
+		pln.consider_minimum_order_qty = 1
+		pln.ignore_existing_ordered_qty = 1
+		mr_items = get_items_for_material_requests(
+			pln.as_dict(), warehouses=[{"warehouse": source_warehouse}]
+		)
+
+		rows_by_type = {d.get("material_request_type"): d for d in mr_items}
+		self.assertEqual(rows_by_type["Material Transfer"].get("quantity"), 4)
+		self.assertEqual(rows_by_type["Purchase"].get("quantity"), 110.232)
+
 	def test_fg_item_quantity(self):
 		fg_item = make_item(properties={"is_stock_item": 1}).name
 		rm_item = make_item(properties={"is_stock_item": 1}).name