Reorganized text db function tests.

tests/db_functions/text/test_lower.py

@@ -0,0 +1,42 @@
+from django.db.models import CharField
+from django.db.models.functions import Lower
+from django.test import TestCase
+
+from ..models import Author
+
+
+class LowerTests(TestCase):
+
+    def test_basic(self):
+        Author.objects.create(name='John Smith', alias='smithj')
+        Author.objects.create(name='Rhonda')
+        authors = Author.objects.annotate(lower_name=Lower('name'))
+        self.assertQuerysetEqual(
+            authors.order_by('name'), ['john smith', 'rhonda'],
+            lambda a: a.lower_name
+        )
+        Author.objects.update(name=Lower('name'))
+        self.assertQuerysetEqual(
+            authors.order_by('name'), [
+                ('john smith', 'john smith'),
+                ('rhonda', 'rhonda'),
+            ],
+            lambda a: (a.lower_name, a.name)
+        )
+
+    def test_num_args(self):
+        with self.assertRaisesMessage(TypeError, "'Lower' takes exactly 1 argument (2 given)"):
+            Author.objects.update(name=Lower('name', 'name'))
+
+    def test_transform(self):
+        try:
+            CharField.register_lookup(Lower)
+            Author.objects.create(name='John Smith', alias='smithj')
+            Author.objects.create(name='Rhonda')
+            authors = Author.objects.filter(name__lower__exact='john smith')
+            self.assertQuerysetEqual(
+                authors.order_by('name'), ['John Smith'],
+                lambda a: a.name
+            )
+        finally:
+            CharField._unregister_lookup(Lower)