This commit is related to the article BAEL-7084 (#15070)

This commit aims to add a test class "XMLStringToDocumentObjectUnitTest.java" that provides a test method to convert XML string into a Document object in Java.

xml-2/src/test/java/com/baeldung/xml/xml2document/XMLStringToDocumentObjectUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.xml2document;
+
+import org.junit.Test;
+import org.w3c.dom.*;
+import org.xml.sax.InputSource;
+import org.xml.sax.SAXException;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+
+import java.io.IOException;
+import java.io.StringReader;
+
+import static org.junit.Assert.assertEquals;
+
+public class XMLStringToDocumentObjectUnitTest {
+    @Test
+    public void givenValidXMLString_whenParsing_thenDocumentIsCorrect() throws ParserConfigurationException {
+        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
+        DocumentBuilder builder = factory.newDocumentBuilder();
+        String xmlString = "<root><element>XML Parsing Example</element></root>";
+        InputSource is = new InputSource(new StringReader(xmlString));
+        Document xmlDoc = null;
+        try {
+            xmlDoc = builder.parse(is);
+        } catch (SAXException e) {
+            throw new RuntimeException(e);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        assertEquals("root", xmlDoc.getDocumentElement().getNodeName());
+        assertEquals("element", xmlDoc.getDocumentElement().getElementsByTagName("element").item(0).getNodeName());
+        assertEquals("XML Parsing Example", xmlDoc.getDocumentElement().getElementsByTagName("element").item(0).getTextContent());
+    }
+}