feat(configurator): per-line lot pricing (derive unit price, keep qty)

fusion_plating/fusion_plating_configurator/tests/test_charge_tax_lot.py

@@ -44,3 +44,13 @@ class TestChargeTaxLot(TransactionCase):
         self.assertEqual(wiz.total_subtotal, 50.0)
         self.assertAlmostEqual(wiz.total_tax, 19.5, places=2)
         self.assertAlmostEqual(wiz.total_amount, 169.5, places=2)
+
+    # ----- Task 4: lot pricing -----
+    def test_lot_onchange_derives_unit_price(self):
+        wiz = self._make_wizard()
+        line = self.env['fp.direct.order.line'].new({
+            'wizard_id': wiz.id, 'quantity': 500, 'lot_total': 1000.0,
+            'is_lot_priced': True,
+        })
+        line._onchange_lot_pricing()
+        self.assertEqual(line.unit_price, 2.0)