greg.tests: convert OrganizationalUnit model tests to pytest

Fixes: GREG-14

greg/tests/models/test_organizational_unit.py

+import pytest
+
+from greg.models import OrganizationalUnit
+
+
+@pytest.mark.django_db
+def test_set_parent():
+    parent = OrganizationalUnit.objects.create(orgreg_id="parent")
+    child = OrganizationalUnit.objects.create(orgreg_id="child", parent=parent)
+    assert list(OrganizationalUnit.objects.filter(parent__id=parent.id)) == [child]

greg/tests/test_models.py

@@ -89,20 +89,3 @@ class ConsentModelTest(TestCase):
         person.consents.add(
             consent, through_defaults={"consent_given_at": "2021-06-20"}
         )
-
-
-class OrganizationalUnitTest(TestCase):
-    def test_set_parent_for_unit(self):
-        parent = OrganizationalUnit.objects.create(
-            orgreg_id="12345", name_en="Parent unit", name_nb="Foreldreseksjon"
-        )
-        child = OrganizationalUnit.objects.create(
-            orgreg_id="123456",
-            name_en="Child unit",
-            name_nb="Barneseksjon",
-            parent=parent,
-        )
-
-        query_result = OrganizationalUnit.objects.filter(parent__id=parent.id)
-        self.assertEqual(1, len(query_result))
-        self.assertIn(child, query_result)