Add couple more tests.

data/data_test.go

diff --git a/data/data_test.go b/data/data_test.go
index a538d54..7d45038 100644
--- a/data/data_test.go
+++ b/data/data_test.go
@@ -105,6 +105,7 @@
 
 		for i := 0; i < count+1; i++ {
 			<-finished
+			Expect(db.Stats().OpenConnections).Should(BeNumerically("<=", 10))
 		}
 		Expect(db.Stats().OpenConnections).To(Equal(10))
 	}, 10)
@@ -126,6 +127,7 @@
 
 		for i := 0; i < count; i++ {
 			<-finished
+			Expect(db.Stats().OpenConnections).To(Equal(1))
 		}
 		// Only one connection should get opened, as connections are serialized.
 		Expect(db.Stats().OpenConnections).To(Equal(1))