diff --git a/specifyweb/backend/businessrules/tests/test_borrow.py b/specifyweb/backend/businessrules/tests/test_borrow.py
new file mode 100644
index 00000000000..356b0ea5bbd
--- /dev/null
+++ b/specifyweb/backend/businessrules/tests/test_borrow.py
@@ -0,0 +1,206 @@
+from decimal import Decimal
+
+from django.utils import timezone
+
+from specifyweb.specify import models
+from specifyweb.specify.tests.test_api import ApiTests
+
+
+class BorrowTests(ApiTests):
+    def test_fill_invoice_number_and_date(self):
+        borrow_date = timezone.now()
+
+        borrow = models.Borrow.objects.create(
+            collectionmemberid=self.collection.id,
+            invoicenumber='BORROW-8524-001',
+            borrowdate=borrow_date,
+        )
+
+        fetched_borrow = models.Borrow.objects.get(id=borrow.id)
+
+        self.assertEqual(
+            fetched_borrow.invoicenumber,
+            'BORROW-8524-001',
+        )
+        self.assertEqual(
+            fetched_borrow.borrowdate,
+            borrow_date,
+        )
+
+    def test_add_existing_agent_to_borrow(self):
+        borrow = models.Borrow.objects.create(
+            collectionmemberid=self.collection.id,
+            invoicenumber='BORROW-AGENT-001',
+        )
+
+        borrow_agent = borrow.borrowagents.create(
+            agent=self.agent,
+            collectionmemberid=self.collection.id,
+            role='Borrower',
+        )
+
+        fetched_borrow_agent = models.Borrowagent.objects.get(
+            id=borrow_agent.id,
+        )
+
+        self.assertEqual(
+            fetched_borrow_agent.borrow.id,
+            borrow.id,
+        )
+        self.assertEqual(
+            fetched_borrow_agent.agent.id,
+            self.agent.id,
+        )
+        self.assertEqual(
+            fetched_borrow_agent.role,
+            'Borrower',
+        )
+
+    def test_create_new_agent_for_borrow(self):
+        borrow = models.Borrow.objects.create(
+            collectionmemberid=self.collection.id,
+            invoicenumber='BORROW-NEW-AGENT-001',
+        )
+
+        new_agent = models.Agent.objects.create(
+            agenttype=0,
+            firstname='New',
+            lastname='Borrow Agent',
+            division=self.division,
+        )
+
+        borrow_agent = models.Borrowagent.objects.create(
+            borrow=borrow,
+            agent=new_agent,
+            collectionmemberid=self.collection.id,
+            role='Borrower',
+        )
+
+        fetched_agent = models.Agent.objects.get(id=new_agent.id)
+        fetched_borrow_agent = models.Borrowagent.objects.get(
+            id=borrow_agent.id,
+        )
+
+        self.assertEqual(
+            fetched_agent.firstname,
+            'New',
+        )
+        self.assertEqual(
+            fetched_agent.lastname,
+            'Borrow Agent',
+        )
+        self.assertEqual(
+            fetched_agent.agenttype,
+            0,
+        )
+        self.assertEqual(
+            fetched_agent.division,
+            self.division,
+        )
+        self.assertEqual(
+            fetched_borrow_agent.borrow,
+            borrow,
+        )
+        self.assertEqual(
+            fetched_borrow_agent.agent,
+            new_agent,
+        )
+        self.assertEqual(
+            fetched_borrow_agent.role,
+            'Borrower',
+        )
+
+    def test_add_shipment_with_all_fields_to_borrow(self):
+        shipment_date = timezone.now()
+
+        borrow = models.Borrow.objects.create(
+            collectionmemberid=self.collection.id,
+            invoicenumber='BORROW-SHIPMENT-001',
+        )
+
+        shipment = borrow.shipments.create(
+            shipmentnumber='BORROW-SHIPMENT-001',
+            shipmentdate=shipment_date,
+            shipmentmethod='Courier',
+            numberofpackages=3,
+            insuredforamount='500.00',
+            weight='12.5 kg',
+            number1=Decimal('10.25'),
+            number2=Decimal('20.50'),
+            remarks='Borrow shipment remarks',
+            text1='Borrow shipment text one',
+            text2='Borrow shipment text two',
+            yesno1=True,
+            yesno2=False,
+            shipper=self.agent,
+            discipline=self.discipline,
+        )
+
+        fetched_shipment = models.Shipment.objects.get(
+            id=shipment.id,
+        )
+
+        self.assertEqual(
+            fetched_shipment.borrow,
+            borrow,
+        )
+        self.assertEqual(
+            fetched_shipment.shipmentnumber,
+            'BORROW-SHIPMENT-001',
+        )
+        self.assertEqual(
+            fetched_shipment.shipmentdate,
+            shipment_date,
+        )
+        self.assertEqual(
+            fetched_shipment.shipmentmethod,
+            'Courier',
+        )
+        self.assertEqual(
+            fetched_shipment.numberofpackages,
+            3,
+        )
+        self.assertEqual(
+            fetched_shipment.insuredforamount,
+            '500.00',
+        )
+        self.assertEqual(
+            fetched_shipment.weight,
+            '12.5 kg',
+        )
+        self.assertEqual(
+            fetched_shipment.number1,
+            Decimal('10.25'),
+        )
+        self.assertEqual(
+            fetched_shipment.number2,
+            Decimal('20.50'),
+        )
+        self.assertEqual(
+            fetched_shipment.remarks,
+            'Borrow shipment remarks',
+        )
+        self.assertEqual(
+            fetched_shipment.text1,
+            'Borrow shipment text one',
+        )
+        self.assertEqual(
+            fetched_shipment.text2,
+            'Borrow shipment text two',
+        )
+        self.assertIs(
+            fetched_shipment.yesno1,
+            True,
+        )
+        self.assertIs(
+            fetched_shipment.yesno2,
+            False,
+        )
+        self.assertEqual(
+            fetched_shipment.shipper,
+            self.agent,
+        )
+        self.assertEqual(
+            fetched_shipment.discipline,
+            self.discipline,
+        )