Add black check to unit test.

Author: WaVEV

tests/model_fields_/test_objectidfield.py

@@ -1,9 +1,13 @@
+import shutil
+
 from bson import ObjectId
 from django.core import exceptions
 from django.test import SimpleTestCase
 
 from django_mongodb.fields import ObjectIdField
 
+HAS_BLACK = shutil.which("black")
+
 
 class MethodTests(SimpleTestCase):
     def test_deconstruct(self):
@@ -29,6 +33,9 @@ def test_to_python(self):
     def test_to_python_invalid_value(self):
         for invalid_value in [3, "None", {}, []]:
             with self.subTest(invalid_value=invalid_value):
-                msg = f"['“{invalid_value}” value must be an Object Id.']"
+                if HAS_BLACK:
+                    msg = f'["“{invalid_value}” value must be an Object Id."]'
+                else:
+                    msg = f"['“{invalid_value}” value must be an Object Id.']"
                 with self.assertRaisesMessage(exceptions.ValidationError, msg):
                     ObjectIdField().to_python(invalid_value)