fix code

hutool-poi/src/test/java/cn/hutool/poi/excel/ExcelFileUtilTest.java

@@ -0,0 +1,33 @@
+package cn.hutool.poi.excel;
+
+import cn.hutool.core.io.FileUtil;
+import cn.hutool.core.io.IoUtil;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.InputStream;
+
+public class ExcelFileUtilTest {
+
+	@Test
+	public void xlsTest(){
+		InputStream in = FileUtil.getInputStream("aaa.xls");
+		try{
+			Assert.assertTrue(ExcelFileUtil.isXls(in));
+			Assert.assertFalse(ExcelFileUtil.isXlsx(in));
+		} finally {
+			IoUtil.close(in);
+		}
+	}
+
+	@Test
+	public void xlsxTest(){
+		InputStream in = FileUtil.getInputStream("aaa.xlsx");
+		try{
+			Assert.assertFalse(ExcelFileUtil.isXls(in));
+			Assert.assertTrue(ExcelFileUtil.isXlsx(in));
+		} finally {
+			IoUtil.close(in);
+		}
+	}
+}