Split model_fields tests into different files.

tests/model_fields/test_filefield.py

@@ -0,0 +1,52 @@
+from django.test import TestCase
+
+from .models import Document
+
+
+class FileFieldTests(TestCase):
+
+    def test_clearable(self):
+        """
+        FileField.save_form_data() will clear its instance attribute value if
+        passed False.
+        """
+        d = Document(myfile='something.txt')
+        self.assertEqual(d.myfile, 'something.txt')
+        field = d._meta.get_field('myfile')
+        field.save_form_data(d, False)
+        self.assertEqual(d.myfile, '')
+
+    def test_unchanged(self):
+        """
+        FileField.save_form_data() considers None to mean "no change" rather
+        than "clear".
+        """
+        d = Document(myfile='something.txt')
+        self.assertEqual(d.myfile, 'something.txt')
+        field = d._meta.get_field('myfile')
+        field.save_form_data(d, None)
+        self.assertEqual(d.myfile, 'something.txt')
+
+    def test_changed(self):
+        """
+        FileField.save_form_data(), if passed a truthy value, updates its
+        instance attribute.
+        """
+        d = Document(myfile='something.txt')
+        self.assertEqual(d.myfile, 'something.txt')
+        field = d._meta.get_field('myfile')
+        field.save_form_data(d, 'else.txt')
+        self.assertEqual(d.myfile, 'else.txt')
+
+    def test_delete_when_file_unset(self):
+        """
+        Calling delete on an unset FileField should not call the file deletion
+        process, but fail silently (#20660).
+        """
+        d = Document()
+        d.myfile.delete()
+
+    def test_refresh_from_db(self):
+        d = Document.objects.create(myfile='something.txt')
+        d.refresh_from_db()
+        self.assertIs(d.myfile.instance, d)