fix: Remove irrelevant code
diff --git a/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py b/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
index 28a9bdd..f799279 100644
--- a/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
+++ b/erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py
@@ -1142,36 +1142,6 @@
 		if update:
 			self.db_set('status', self.status, update_modified = update_modified)
 
-# to get details of purchase invoice/receipt from which this doc was created for exchange rate difference handling
-def get_purchase_document_details(doc):
-	if doc.doctype == 'Purchase Invoice':
-		doc_reference = 'purchase_receipt'
-		items_reference = 'pr_detail'
-		parent_doctype = 'Purchase Receipt'
-		child_doctype = 'Purchase Receipt Item'
-	else:
-		doc_reference = 'purchase_invoice'
-		items_reference = 'purchase_invoice_item'
-		parent_doctype = 'Purchase Invoice'
-		child_doctype = 'Purchase Invoice Item'
-
-	purchase_receipts_or_invoices = []
-	items = []
-
-	for item in doc.get('items'):
-		if item.get(doc_reference):
-			purchase_receipts_or_invoices.append(item.get(doc_reference))
-		if item.get(items_reference):
-			items.append(item.get(items_reference))
-	
-	exchange_rate_map = frappe._dict(frappe.get_all(parent_doctype, filters={'name': ('in',
-		purchase_receipts_or_invoices)}, fields=['name', 'conversion_rate'], as_list=1))
-
-	net_rate_map = frappe._dict(frappe.get_all(child_doctype, filters={'name': ('in',
-		items)}, fields=['name', 'net_rate'], as_list=1))
-
-	return exchange_rate_map, net_rate_map
-
 def get_list_context(context=None):
 	from erpnext.controllers.website_list_for_contact import get_list_context
 	list_context = get_list_context(context)
diff --git a/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py b/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py
index 9a5064f..fd6ac16 100644
--- a/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py
+++ b/erpnext/stock/doctype/purchase_receipt/test_purchase_receipt.py
@@ -1052,33 +1052,6 @@
 
 		frappe.db.set_value('Company', company, 'enable_perpetual_inventory_for_non_stock_items', before_test_value)
 
-	def test_purchase_receipt_with_exchange_rate_difference(self):
-		from erpnext.accounts.doctype.purchase_invoice.test_purchase_invoice import make_purchase_invoice as create_purchase_invoice
-		from erpnext.accounts.doctype.purchase_invoice.purchase_invoice import make_purchase_receipt as create_purchase_receipt
-		
-		pi = create_purchase_invoice(company="_Test Company with perpetual inventory",
-			cost_center = "Main - TCP1",
-			warehouse = "Stores - TCP1",
-			expense_account ="_Test Account Cost for Goods Sold - TCP1",
-			currency = "USD", conversion_rate = 70)
-		
-		pr = create_purchase_receipt(pi.name)
-		pr.conversion_rate = 80
-		pr.items[0].purchase_invoice = pi.name
-		pr.items[0].purchase_invoice_item = pi.items[0].name
-
-		pr.save()
-		pr.submit()
-
-		# Get exchnage gain and loss account
-		exchange_gain_loss_account = frappe.db.get_value('Company', pr.company, 'exchange_gain_loss_account')
-
-		# fetching the latest GL Entry with exchange gain and loss account account
-		amount = frappe.db.get_value('GL Entry', {'account': exchange_gain_loss_account, 'voucher_no': pr.name}, 'credit')
-		discrepancy_caused_by_exchange_rate_diff = abs(pi.items[0].base_net_amount - pr.items[0].base_net_amount)
-
-		self.assertEqual(discrepancy_caused_by_exchange_rate_diff, amount)
-
 	def test_payment_terms_are_fetched_when_creating_purchase_invoice(self):
 		from erpnext.accounts.doctype.payment_entry.test_payment_entry import create_payment_terms_template
 		from erpnext.accounts.doctype.purchase_invoice.test_purchase_invoice import make_purchase_invoice