@Override
  public SqlType returnType() {
    return outputSchema;
  }
@Test
  public void shouldReturnSqlReturnType() {
    // When:
    final TestAggFunc aggFunc = new TestAggFunc(
        "funcName",
        Collections.singletonList(0),
        initialValueSupplier,
        SqlTypes.BIGINT,
        Collections.singletonList(new ParameterInfo("val", ParamTypes.STRING, "", false)),
        "the description"
    );

    // Then:
    assertThat(aggFunc.returnType(), is(SqlTypes.BIGINT));
  }