diff --git a/tests/aggregate/test_lazy_select_expressions.py b/tests/aggregate/test_lazy_select_expressions.py
new file mode 100644
index 0000000..73b1f47
--- /dev/null
+++ b/tests/aggregate/test_lazy_select_expressions.py
@@ -0,0 +1,51 @@
+from decimal import Decimal
+import sqlalchemy as sa
+from sqlalchemy_utils.aggregates import aggregated_attr
+from tests import TestCase
+
+
+class TestLazyEvaluatedSelectExpressionsForAggregates(TestCase):
+    dns = 'postgres://postgres@localhost/sqlalchemy_utils_test'
+
+    def create_models(self):
+        class Catalog(self.Base):
+            __tablename__ = 'catalog'
+            id = sa.Column(sa.Integer, primary_key=True)
+            name = sa.Column(sa.Unicode(255))
+
+            @aggregated_attr('products')
+            def net_worth(self):
+                return sa.Column(sa.Numeric, default=0)
+
+            @net_worth.expression
+            def net_worth_expr(self):
+                return sa.func.sum(Product.price)
+
+            products = sa.orm.relationship('Product', backref='catalog')
+
+        class Product(self.Base):
+            __tablename__ = 'product'
+            id = sa.Column(sa.Integer, primary_key=True)
+            name = sa.Column(sa.Unicode(255))
+            price = sa.Column(sa.Numeric)
+
+            catalog_id = sa.Column(sa.Integer, sa.ForeignKey('catalog.id'))
+
+        self.Catalog = Catalog
+        self.Product = Product
+
+    def test_assigns_aggregates(self):
+        catalog = self.Catalog(
+            name=u'Some catalog'
+        )
+        self.session.add(catalog)
+        self.session.commit()
+        product = self.Product(
+            name=u'Some product',
+            price=Decimal('1000'),
+            catalog=catalog
+        )
+        self.session.add(product)
+        self.session.commit()
+        self.session.refresh(catalog)
+        assert catalog.net_worth == Decimal('1000')
diff --git a/tests/aggregate/test_multiple_aggregates_per_class.py b/tests/aggregate/test_multiple_aggregates_per_class.py
new file mode 100644
index 0000000..b49bc79
--- /dev/null
+++ b/tests/aggregate/test_multiple_aggregates_per_class.py
@@ -0,0 +1,77 @@
+import sqlalchemy as sa
+from sqlalchemy_utils.aggregates import aggregated_attr
+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_attr('comments')
+            def comment_count(self):
+                return sa.Column(sa.Integer, default=0)
+
+            @aggregated_attr('comments', sa.func.max)
+            def last_comment_id(self):
+                return sa.Column(sa.Integer)
+
+            comments = sa.orm.relationship(
+                'Comment',
+                backref='thread'
+            )
+
+        Thread.last_comment = sa.orm.relationship(
+            'Comment',
+            primaryjoin='Thread.last_comment_id == Comment.id',
+            foreign_keys=[Thread.last_comment_id],
+            viewonly=True
+        )
+
+        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'))
+
+        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
+        assert thread.last_comment_id == comment.id
+
+    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
+        assert thread.last_comment_id == 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
+        assert thread.last_comment_id is None