Polishing contribution

Closes gh-35477

Author: bclozel

spring-web/src/test/java/org/springframework/web/util/HtmlCharacterEntityDecoderTest.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2002-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.util;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+
+/**
+ * Tests for {@link HtmlCharacterEntityDecoder}.
+ */
+class HtmlCharacterEntityDecoderTests {
+
+	@Test
+	void unescapeHandlesSupplementaryCharactersAsDecimal() {
+		String expectedCharacter = "😀";
+		String decimalEntity = "😀";
+		String actualResultFromDecimal = HtmlUtils.htmlUnescape(decimalEntity);
+		assertThat(actualResultFromDecimal).as("Decimal entity was not converted correctly.").isEqualTo(expectedCharacter);
+	}
+
+	@Test
+	void unescapeHandlesSupplementaryCharactersAsHexadecimal() {
+		String expectedCharacter = "😀";
+		String hexEntity = "😀";
+		String actualResultFromHex = HtmlUtils.htmlUnescape(hexEntity);
+		assertThat(actualResultFromHex).as("Hexadecimal entity was not converted correctly.").isEqualTo(expectedCharacter);
+	}
+
+	@Test
+	void unescapeHandlesBasicEntities() {
+		String input = "<p>Tom & Jerry's "Show"</p>";
+		String expectedOutput = "<p>Tom & Jerry's \"Show\"</p>";
+		String actualOutput = HtmlUtils.htmlUnescape(input);
+		assertThat(actualOutput).as("Basic HTML entities were not unescaped correctly.").isEqualTo(expectedOutput);
+	}
+
+}