Reorganized text db function tests.

tests/db_functions/text/test_concat.py

@@ -0,0 +1,81 @@
+from unittest import skipUnless
+
+from django.db import connection
+from django.db.models import CharField, TextField, Value as V
+from django.db.models.functions import Concat, ConcatPair, Upper
+from django.test import TestCase
+from django.utils import timezone
+
+from ..models import Article, Author
+
+lorem_ipsum = """
+    Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
+    tempor incididunt ut labore et dolore magna aliqua."""
+
+
+class ConcatTests(TestCase):
+
+    def test_basic(self):
+        Author.objects.create(name='Jayden')
+        Author.objects.create(name='John Smith', alias='smithj', goes_by='John')
+        Author.objects.create(name='Margaret', goes_by='Maggie')
+        Author.objects.create(name='Rhonda', alias='adnohR')
+        authors = Author.objects.annotate(joined=Concat('alias', 'goes_by'))
+        self.assertQuerysetEqual(
+            authors.order_by('name'), [
+                '',
+                'smithjJohn',
+                'Maggie',
+                'adnohR',
+            ],
+            lambda a: a.joined
+        )
+
+    def test_gt_two_expressions(self):
+        with self.assertRaisesMessage(ValueError, 'Concat must take at least two expressions'):
+            Author.objects.annotate(joined=Concat('alias'))
+
+    def test_many(self):
+        Author.objects.create(name='Jayden')
+        Author.objects.create(name='John Smith', alias='smithj', goes_by='John')
+        Author.objects.create(name='Margaret', goes_by='Maggie')
+        Author.objects.create(name='Rhonda', alias='adnohR')
+        authors = Author.objects.annotate(
+            joined=Concat('name', V(' ('), 'goes_by', V(')'), output_field=CharField()),
+        )
+        self.assertQuerysetEqual(
+            authors.order_by('name'), [
+                'Jayden ()',
+                'John Smith (John)',
+                'Margaret (Maggie)',
+                'Rhonda ()',
+            ],
+            lambda a: a.joined
+        )
+
+    def test_mixed_char_text(self):
+        Article.objects.create(title='The Title', text=lorem_ipsum, written=timezone.now())
+        article = Article.objects.annotate(
+            title_text=Concat('title', V(' - '), 'text', output_field=TextField()),
+        ).get(title='The Title')
+        self.assertEqual(article.title + ' - ' + article.text, article.title_text)
+        # Wrap the concat in something else to ensure that text is returned
+        # rather than bytes.
+        article = Article.objects.annotate(
+            title_text=Upper(Concat('title', V(' - '), 'text', output_field=TextField())),
+        ).get(title='The Title')
+        expected = article.title + ' - ' + article.text
+        self.assertEqual(expected.upper(), article.title_text)
+
+    @skipUnless(connection.vendor == 'sqlite', "sqlite specific implementation detail.")
+    def test_coalesce_idempotent(self):
+        pair = ConcatPair(V('a'), V('b'))
+        # Check nodes counts
+        self.assertEqual(len(list(pair.flatten())), 3)
+        self.assertEqual(len(list(pair.coalesce().flatten())), 7)  # + 2 Coalesce + 2 Value()
+        self.assertEqual(len(list(pair.flatten())), 3)
+
+    def test_sql_generation_idempotency(self):
+        qs = Article.objects.annotate(description=Concat('title', V(': '), 'summary'))
+        # Multiple compilations should not alter the generated query.
+        self.assertEqual(str(qs.query), str(qs.all().query))