@Test
  public void testDruidObjectSerializerwithNullTimestamp() throws Exception {
    // Create, initialize, and test the SerDe
    DruidSerDe serDe = new DruidSerDe();
    Configuration conf = new Configuration();
    Properties tbl;
    // Mixed source (all types)
    tbl = createPropertiesSource(COLUMN_NAMES, COLUMN_TYPES);
    serDe.initialize(conf, tbl, null);
    Object[] row = new Object[]{
        null,
        new Text("dim1_val"),
        new HiveCharWritable(new HiveChar("dim2_v", 6)),
        new HiveVarcharWritable(new HiveVarchar("dim3_val", 8)),
        new DoubleWritable(10669.3D),
        new FloatWritable(10669.45F),
        new LongWritable(1113939),
        new IntWritable(1112123),
        new ShortWritable((short) 12),
        new ByteWritable((byte) 0),
        null
        // granularity
    };
    expectedEx.expect(NullPointerException.class);
    expectedEx.expectMessage("Timestamp column cannot have null value");
    // should fail as timestamp is null
    serializeObject(tbl, serDe, row, DRUID_WRITABLE);
  }
Basic tests for Druid SerDe. The examples are taken from Druid 0.9.1.1
documentation.
druid-handler/src/test/org/apache/hadoop/hive/druid/serde/TestDruidSerDe.java