Add test coverage for DomUtils

See gh-33768

spring-core/src/test/java/org/springframework/util/xml/DomUtilsTest.java

@@ -0,0 +1,129 @@
+package org.springframework.util.xml;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.xml.sax.SAXException;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class DomUtilsTest {
+
+	private Element elementWithText;
+
+	private Element elementWithComment;
+
+	private Element elementWithEntityReference;
+
+	private Element elementWithEmptyReference;
+
+	private static final String CLASS = "class";
+
+	private static final String PRINCIPAL = "principal";
+
+	private static final String HEAD_MASTER = "headMaster";
+
+	@BeforeEach
+	void setup() throws ParserConfigurationException, IOException, SAXException {
+		DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
+		DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
+		Document documentWithText = documentBuilder.parse(new File("src/test/resources/scanned-resources/resource#element-with-text.xml"));
+		Document documentWithComment = documentBuilder.parse(new File("src/test/resources/scanned-resources/resource#element-with-comment.xml"));
+		Document documentWithEntityReference = documentBuilder.parse(new File("src/test/resources/scanned-resources/resource#element-with-entity-reference.xml"));
+		Document documentWithEmptyValue = documentBuilder.parse(new File("src/test/resources/scanned-resources/resource#element-with-empty-reference.xml"));
+		elementWithText = documentWithText.getDocumentElement();
+		elementWithComment = documentWithComment.getDocumentElement();
+		elementWithEntityReference = documentWithEntityReference.getDocumentElement();
+		elementWithEmptyReference = documentWithEmptyValue.getDocumentElement();
+	}
+
+	@Test
+	void getChildElementsByTagNameTestNodeInstanceOfElementAndDesiredElementsPresent() {
+		List<Element> childElements = DomUtils.getChildElementsByTagName(elementWithText, CLASS, PRINCIPAL);
+		assertAll(
+				() -> assertEquals(3, childElements.size()),
+				() -> assertEquals(CLASS, childElements.get(0).getNodeName()),
+				() -> assertEquals(CLASS, childElements.get(1).getNodeName()),
+				() -> assertEquals(PRINCIPAL, childElements.get(2).getNodeName())
+		);
+	}
+
+	@Test
+	void getChildElementsByTagNameTestNodeInstanceOfElementAndDesiredElementsNotPresent() {
+		List<Element>  childElements = DomUtils.getChildElementsByTagName(elementWithText, HEAD_MASTER);
+		assertEquals(0, childElements.size());
+	}
+
+	@Test
+	void getChildElementByTagNameTestElementPresentInChildNodeList() {
+		Element childElement = DomUtils.getChildElementByTagName(elementWithText, PRINCIPAL);
+		assertNotNull(childElement);
+	}
+
+	@Test
+	void getChildElementByTagNameTestElementPresentInChildNodeListAndChildElementsDoNotHaveSampleTag() {
+		Element childElement = DomUtils.getChildElementByTagName(elementWithText, HEAD_MASTER);
+		assertNull(childElement);
+	}
+
+	@Test
+	void getChildElementValueByTagNameTestElementPresentInChildNodeList() {
+		assertEquals("Fox Test", DomUtils.getChildElementValueByTagName(elementWithText, "guard"));
+	}
+
+	@Test
+	void getChildElementValueByTagNameTestElementWithoutChild() {
+		assertNull(DomUtils.getChildElementValueByTagName(elementWithText, "math tutor"));
+	}
+
+	@Test
+	void getChildElementsTestWithValidChildNodes() {
+		List<Element> childElements = DomUtils.getChildElements(elementWithText);
+		assertAll(
+				() -> assertEquals(4, childElements.size())
+		);
+	}
+
+	@Test
+	void getTextValueTestWithCharacterDataNode() {
+		assertTrue(DomUtils.getTextValue(elementWithText).contains("TestSchool"));
+	}
+
+	@Test
+	void getTextValueWithCommentInXml() {
+		assertTrue(DomUtils.getTextValue(elementWithComment).isBlank());
+	}
+
+	@Test
+	void getTextValueWithEntityReferenceInXml() {
+		assertTrue(DomUtils.getTextValue(elementWithEntityReference).contains("&"));
+	}
+
+	@Test
+	void getTextValueWithEmptyReferenceInXml() {
+		assertTrue(DomUtils.getTextValue(elementWithEmptyReference).isBlank());
+	}
+
+	@Test
+	void nodeNameTestTrueCondition() {
+		assertTrue(DomUtils.nodeNameEquals(elementWithText, "school"));
+	}
+
+	@Test
+	void nodeNameTestFalseCondition() {
+		assertFalse(DomUtils.nodeNameEquals(elementWithText, "college"));
+	}
+
+	@Test
+	void createContentHandlerTest() {
+		assertNotNull(DomUtils.createContentHandler(elementWithText));
+	}
+}