diff --git a/space/data_test.go b/space/data_test.go
new file mode 100644
index 0000000..b15c33b
--- /dev/null
+++ b/space/data_test.go
@@ -0,0 +1,58 @@
+package space
+
+import (
+	"runtime"
+	"testing"
+	"unsafe"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/outofforest/quantum/types"
+)
+
+func TestDataNode(t *testing.T) {
+	requireT := require.New(t)
+	node := make([]byte, types.NodeLength)
+	defer runtime.KeepAlive(node)
+
+	nodeP := unsafe.Pointer(&node[0])
+
+	dataNode, err := NewDataNodeAssistant[uint32, uint16]()
+	requireT.NoError(err)
+
+	keyHashes := dataNode.KeyHashes(nodeP)
+	requireT.Equal(dataNode.NumOfItems(), uint64(len(keyHashes)))
+	requireT.Equal(nodeP, unsafe.Pointer(&keyHashes[0]))
+
+	requireT.GreaterOrEqual(uintptr(nodeP)+types.NodeLength,
+		uintptr(unsafe.Pointer(dataNode.Item(nodeP, dataNode.ItemOffset(dataNode.NumOfItems())))))
+
+	for i := range dataNode.NumOfItems() {
+		item := dataNode.Item(nodeP, dataNode.ItemOffset(i))
+		item.Key = uint32(i)
+		item.Value = uint16(i)
+	}
+
+	itemP := unsafe.Add(nodeP, dataNode.NumOfItems()*types.UInt64Length)
+	for i := range dataNode.NumOfItems() {
+		requireT.Equal(uint32(i), *(*uint32)(itemP))                //nolint:testifylint
+		requireT.Equal(uint16(i), *(*uint16)(unsafe.Add(itemP, 4))) //nolint:testifylint
+
+		itemP = unsafe.Add(itemP, 8)
+	}
+}
+
+func TestMaxDataNode(t *testing.T) {
+	requireT := require.New(t)
+
+	dataNode, err := NewDataNodeAssistant[uint64, [4080]byte]()
+	requireT.NoError(err)
+	requireT.Equal(uint64(1), dataNode.NumOfItems())
+}
+
+func TestTooBigNode(t *testing.T) {
+	requireT := require.New(t)
+
+	_, err := NewDataNodeAssistant[uint64, [4081]byte]()
+	requireT.Error(err)
+}