add test

hutool-core/src/test/java/cn/hutool/core/date/Issue3798Test.java

@@ -0,0 +1,22 @@
+package cn.hutool.core.date;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.TimeZone;
+
+public class Issue3798Test {
+	@Test
+	void parseTest() {
+		final String iso_datetime1 = "2000-01-01T12:00:00+08:00";
+		final DateTime parse1 = DateUtil.parse(iso_datetime1);
+		Assertions.assertEquals(TimeZone.getTimeZone("GMT+08:00"), parse1.getTimeZone());
+		Assertions.assertEquals("2000-01-01 12:00:00", parse1.toString());
+
+		// 伦敦时间（Greenwich Mean Time, GMT）和北京时间（China Standard Time, CST）之间的时差是8小时。北京时间比伦敦时间快8小时
+		final String iso_datetime2 = "2000-01-01T12:00:00+00:00";
+		final DateTime parse2 = DateUtil.parse(iso_datetime2);
+		Assertions.assertEquals(TimeZone.getTimeZone("GMT+00:00"), parse2.getTimeZone());
+		Assertions.assertEquals("2000-01-01 20:00:00", parse2.toString(TimeZone.getTimeZone("GMT+08:00")));
+	}
+}