diff --git a/hutool-core/src/test/java/cn/hutool/core/date/DateUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/date/DateUtilTest.java
index 6123d4b76..d769e06b9 100644
--- a/hutool-core/src/test/java/cn/hutool/core/date/DateUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/date/DateUtilTest.java
@@ -364,11 +364,11 @@ public class DateUtilTest {
 
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	@Test
 	public void parseTest6() {
 		String str = "Tue Jun 4 16:25:15 +0800 2019";
 		DateTime dateTime = DateUtil.parse(str);
+		assert dateTime != null;
 		Assert.assertEquals("2019-06-04 16:25:15", dateTime.toString());
 	}
 
@@ -379,12 +379,12 @@ public class DateUtilTest {
 		Assert.assertEquals("2019-06-01 19:45:43", dateTime.toString());
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	@Test
 	public void parseAndOffsetTest() {
 		// 检查UTC时间偏移是否准确
 		String str = "2019-09-17T13:26:17.948Z";
 		DateTime dateTime = DateUtil.parse(str);
+		assert dateTime != null;
 		Assert.assertEquals("2019-09-17 13:26:17", dateTime.toString());
 
 		DateTime offset = DateUtil.offsetHour(dateTime, 8);
@@ -467,7 +467,6 @@ public class DateUtilTest {
 		Assert.assertEquals(dt1, dt2);
 	}
 
-	@SuppressWarnings("ConstantConditions")
 	@Test
 	public void parseUTCTest() {
 		String dateStr1 = "2018-09-13T05:34:31Z";
@@ -497,11 +496,13 @@ public class DateUtilTest {
 
 		dateStr1 = "2018-09-13T13:34:34+0800";
 		dt = DateUtil.parse(dateStr1);
+		assert dt != null;
 		dateStr = dt.toString(TimeZone.getTimeZone("GMT+8:00"));
 		Assert.assertEquals("2018-09-13 13:34:34", dateStr);
 
 		dateStr1 = "2018-09-13T13:34:35+08:00";
 		dt = DateUtil.parse(dateStr1);
+		assert dt != null;
 		dateStr = dt.toString(TimeZone.getTimeZone("GMT+8:00"));
 		Assert.assertEquals("2018-09-13 13:34:35", dateStr);
 
@@ -519,11 +520,13 @@ public class DateUtilTest {
 
 		dateStr1 = "2018-09-13T13:34:38.999+0800";
 		dt = DateUtil.parse(dateStr1);
+		assert dt != null;
 		dateStr = dt.toString(simpleDateFormat);
 		Assert.assertEquals("2018-09-13 13:34:38.999", dateStr);
 
 		dateStr1 = "2018-09-13T13:34:39.999+08:00";
 		dt = DateUtil.parse(dateStr1);
+		assert dt != null;
 		dateStr = dt.toString(simpleDateFormat);
 		Assert.assertEquals("2018-09-13 13:34:39.999", dateStr);
 	}
@@ -563,6 +566,13 @@ public class DateUtilTest {
 		Assert.assertEquals("2019-05-16 17:57:18", Objects.requireNonNull(time).toString());
 	}
 
+	@Test
+	public void parseISOTest() {
+		String dateStr = "2020-04-23T02:31:00.000Z";
+		DateTime time = DateUtil.parse(dateStr);
+		Assert.assertEquals("2020-04-23 02:31:00", Objects.requireNonNull(time).toString());
+	}
+
 	@Test
 	public void endOfYearTest() {
 		DateTime date = DateUtil.date();