added test case and bug fix for (next|previous)(Elements|Siblings) methods

libraries/stdlib/src/kotlin/dom/Dom.kt

@@ -202,23 +202,26 @@ fun Node.nextSiblings() : Iterator<Node> = NextSiblingIterator(this)
 class NextSiblingIterator(var node: Node) : AbstractIterator<Node>() {
 
     override fun computeNext(): Unit {
-        val next = node.getNextSibling()
-        if (next != null) {
-            setNext(next)
+        val nextValue = node.getNextSibling()
+        if (nextValue != null) {
+            setNext(nextValue)
+            node = nextValue
         } else {
             done()
         }
     }
 }
+
 /** Returns an [[Iterator]] over the next siblings of this node */
 fun Node.previousSiblings() : Iterator<Node> = PreviousSiblingIterator(this)
 
 class PreviousSiblingIterator(var node: Node) : AbstractIterator<Node>() {
 
     override fun computeNext(): Unit {
-        val next = node.getPreviousSibling()
-        if (next != null) {
-            setNext(next)
+        val nextValue = node.getPreviousSibling()
+        if (nextValue != null) {
+            setNext(nextValue)
+            node = nextValue
         } else {
             done()
         }

libraries/stdlib/test/dom/NextSiblingTest.kt

@@ -0,0 +1,50 @@
+package test.dom
+
+import kotlin.*
+import kotlin.dom.*
+import kotlin.util.*
+import kotlin.test.*
+import org.w3c.dom.*
+import org.junit.Test as test
+
+class NextSiblingTest {
+
+    test fun nextSibling() {
+        val doc = createDocument()
+
+        doc.addElement("foo") {
+            id = "id1"
+            style = "bold"
+            classes = "bar"
+            addElement("child") {
+                id = "id2"
+                classes = "another"
+                addElement("grandChild") {
+                    id = "id3"
+                    classes = " bar tiny"
+                    addText("Hello World!")
+                // TODO support neater syntax sugar for adding text?
+                // += "Hello World!"
+                }
+                addElement("grandChild2") {
+                    id = "id4"
+                    classes = "tiny thing bar "
+                    addText("Hello World!")
+                // TODO support neater syntax sugar for adding text?
+                // += "Hello World!"
+                }
+            }
+        }
+
+        println("builder document: ${doc.toXmlString()}")
+
+
+        val elems = doc["#id3"]
+        val element = elems.first()
+        val elements = element.nextElements().toList()
+        val nodes = element.nextSiblings().toList()
+
+        assertEquals(1, elements.size())
+        assertEquals(1, nodes.size())
+    }
+}