Add tests for backrefs

tests/aggregate/test_backrefs.py

@@ -0,0 +1,60 @@
+import sqlalchemy as sa
+from sqlalchemy_utils.aggregates import aggregated
+from tests import TestCase
+
+
+class TestAggregateValueGenerationForSimpleModelPaths(TestCase):
+    def create_models(self):
+        class Thread(self.Base):
+            __tablename__ = 'thread'
+            id = sa.Column(sa.Integer, primary_key=True)
+            name = sa.Column(sa.Unicode(255))
+
+            @aggregated('comments', sa.Column(sa.Integer, default=0))
+            def comment_count(self):
+                return sa.func.count('1')
+
+        class Comment(self.Base):
+            __tablename__ = 'comment'
+            id = sa.Column(sa.Integer, primary_key=True)
+            content = sa.Column(sa.Unicode(255))
+            thread_id = sa.Column(sa.Integer, sa.ForeignKey('thread.id'))
+
+            thread = sa.orm.relationship(Thread, backref='comments')
+
+        self.Thread = Thread
+        self.Comment = Comment
+
+    def test_assigns_aggregates_on_insert(self):
+        thread = self.Thread()
+        thread.name = u'some article name'
+        self.session.add(thread)
+        comment = self.Comment(content=u'Some content', thread=thread)
+        self.session.add(comment)
+        self.session.commit()
+        self.session.refresh(thread)
+        assert thread.comment_count == 1
+
+    def test_assigns_aggregates_on_separate_insert(self):
+        thread = self.Thread()
+        thread.name = u'some article name'
+        self.session.add(thread)
+        self.session.commit()
+        comment = self.Comment(content=u'Some content', thread=thread)
+        self.session.add(comment)
+        self.session.commit()
+        self.session.refresh(thread)
+        assert thread.comment_count == 1
+
+    def test_assigns_aggregates_on_delete(self):
+        thread = self.Thread()
+        thread.name = u'some article name'
+        self.session.add(thread)
+        self.session.commit()
+        comment = self.Comment(content=u'Some content', thread=thread)
+        self.session.add(comment)
+        self.session.commit()
+        self.session.delete(comment)
+        self.session.commit()
+        self.session.refresh(thread)
+        assert thread.comment_count == 0