fix!: dont delete customizations when doctypes are deleted

If someone deletes doctype and restores it back all customization are
lost, there's no "real" reason to delete all these customization. They
are only ever active if the doctype is being used.

Explanations:

- Custom field: is used by meta when doctype meta is requested, if meta
  isn't requested then custom field is effectively inactive.
- Client script: loaded by meta when doctype is requested by desk. So
  inactive in deleted state.
- Property setter: loaded by meta, so inactive when doctype isn't
  present.
- Report: will break doctype isn't present, but user should delete them
  manually to avoid loss of "scripts" or anything special they might
  have done. Also report's doctype don't 100% indicate that it's based
  solely on that doctype.

frappe/core/doctype/doctype/test_doctype.py

@@ -1,10 +1,14 @@
 # -*- coding: utf-8 -*-
 # Copyright (c) 2015, Frappe Technologies Pvt. Ltd. and Contributors
 # License: MIT. See LICENSE
+import random
+import string
 import unittest
 from typing import Dict, List, Optional
+from unittest.mock import patch
 
 import frappe
+from frappe.cache_manager import clear_doctype_cache
 from frappe.core.doctype.doctype.doctype import (
 	CannotIndexedError,
 	DoctypeLinkError,
@@ -15,8 +19,8 @@ from frappe.core.doctype.doctype.doctype import (
 	WrongOptionsDoctypeLinkError,
 	validate_links_table_fieldnames,
 )
-
-# test_records = frappe.get_test_records('DocType')
+from frappe.custom.doctype.custom_field.custom_field import create_custom_fields
+from frappe.desk.form.load import getdoc
 
 
 class TestDocType(unittest.TestCase):
@@ -628,10 +632,55 @@ class TestDocType(unittest.TestCase):
 
 		self.assertEqual(test_json.test_json_field["hello"], "world")
 
+	@patch.dict(frappe.conf, {"developer_mode": 1})
+	def test_delete_doctype_with_customization(self):
+		from frappe.custom.doctype.property_setter.property_setter import make_property_setter
+
+		custom_field = "customfield"
+
+		doctype = new_doctype(custom=0).insert().name
+
+		# Create property setter and custom field
+		field = "some_fieldname"
+		make_property_setter(doctype, field, "default", "DELETETHIS", "Data")
+		create_custom_fields({doctype: [{"fieldname": custom_field, "fieldtype": "Data"}]})
+
+		# Create 1 record
+		original_doc = frappe.get_doc(doctype=doctype, custom_field_name="wat").insert()
+		self.assertEqual(original_doc.some_fieldname, "DELETETHIS")
+
+		# delete doctype
+		frappe.delete_doc("DocType", doctype)
+		clear_doctype_cache(doctype)
+
+		# "restore" doctype by inserting doctype with same schema again
+		new_doctype(doctype, custom=0).insert()
+
+		# Ensure basically same doctype getting "restored"
+		restored_doc = frappe.get_last_doc(doctype)
+		verify_fields = ["doctype", field, custom_field]
+		for f in verify_fields:
+			self.assertEqual(original_doc.get(f), restored_doc.get(f))
+
+		# Check form load of restored doctype
+		getdoc(doctype, restored_doc.name)
+
+		# ensure meta - property setter
+		self.assertEqual(frappe.get_meta(doctype).get_field(field).default, "DELETETHIS")
+		frappe.delete_doc("DocType", doctype)
+
 
 def new_doctype(
-	name, unique: bool = False, depends_on: str = "", fields: Optional[List[Dict]] = None, **kwargs
+	name: Optional[str] = None,
+	unique: bool = False,
+	depends_on: str = "",
+	fields: Optional[List[Dict]] = None,
+	**kwargs,
 ):
+	if not name:
+		# Test prefix is required to avoid coverage
+		name = "Test " + "".join(random.sample(string.ascii_lowercase, 10))
+
 	doc = frappe.get_doc(
 		{
 			"doctype": "DocType",

frappe/model/delete_doc.py

@@ -88,10 +88,6 @@ def delete_doc(
 				update_flags(doc, flags, ignore_permissions)
 				check_permission_and_not_submitted(doc)
 
-				frappe.db.delete("Custom Field", {"dt": name})
-				frappe.db.delete("Client Script", {"dt": name})
-				frappe.db.delete("Property Setter", {"doc_type": name})
-				frappe.db.delete("Report", {"ref_doctype": name})
 				frappe.db.delete("Custom DocPerm", {"parent": name})
 				frappe.db.delete("__global_search", {"doctype": name})