@Test
  public void linearFillTest() {
    String[] retArray =
        new String[] {
          "1,null,1,null,1.0,null,t1,",
          "2,2,2,2.0,2.0,true,t2,",
          "3,3,3,3.0,3.0,false,null,",
          "4,4,4,4.0,4.0,null,t4,",
          "5,5,5,5.0,5.0,false,t5,",
          "6,6,6,6.0,6.0,null,t6,",
          "8,8,8,8.0,8.0,true,t8,",
          "9,9,null,9.0,null,true,null,"
        };
    resultSetEqualWithDescOrderTest(
        "select s1, s2, s3, s4, s5, s6 from root.sg1.d1 fill(linear)", expectedHeader, retArray);
  }
[root.sg1.d1 (aligned)]

<p>Time, s1[INT32], s2[INT64], s3[FLOAT], s4[DOUBLE], s5[BOOLEAN], s6[TEXT]<br>
1, null, 1, null, 1.0, null, t1<br>
2, 2, 2, 2.0, 2.0, true, t2<br>
3, 3, null, 3.0, null, false, null<br>
4, null, 4, null, 4.0, null, t4<br>
5, 5, 5, 5.0, 5.0, false, t5<br>
6, null, 6, null, 6.0, false, null<br>
7, null, null, null, null, null, null<br>
8, 8, 8, 8.0, 8.0, true, t8<br>
9, 9, null, 9.0, null, true, null

<p>[root.sg1.d2 (non-aligned)]

<p>Time, s1[INT32], s2[INT64], s3[FLOAT], s4[DOUBLE], s5[BOOLEAN], s6[TEXT]<br>
1, 1, null, 1.0, null, true, null<br>
2, 2, 2, 2.0, 2.0, true, t2<br>
3, null, 3, null, 3.0, null, t3<br>
4, 4, null, 4.0, null, false, null<br>
5, 5, 5, 5.0, 5.0, false, t5<br>
6, 6, null, 6.0, null, false, null<br>
7, null, null, null, null, null, null<br>
8, 8, 8, 8.0, 8.0, true, t8<br>
9, null, 9, null, 9.0, null, t9
integration-test/src/test/java/org/apache/iotdb/db/it/query/IoTDBNullValueFillIT.java