@Test
  public void testNullEmptyCmdArg() throws Throwable {
    final String SCRIPT_TEXT = "set hive.support.concurrency = false;\n" +
        "select 'abc',null,'def' from " + tableName + " limit 1 ;\n";
    final String EXPECTED_PATTERN = "'abc','','def'";

    List<String> argList = getBaseArgs(miniHS2.getBaseJdbcURL());
    argList.add("--nullemptystring=true");
    argList.add("--outputformat=csv");

    testScriptFile(SCRIPT_TEXT, argList, EXPECTED_PATTERN, true);
  }
Select null from table , check if setting null to empty string works - Using beeling cmd line
 argument.
Original beeline/sqlline used to print nulls as empty strings
Print PASSED or FAILED
itests/hive-unit/src/test/java/org/apache/hive/beeline/TestBeeLineWithArgs.java