public DdlCommandResult execute(
      final String sql,
      final DdlCommand ddlCommand,
      final boolean withQuery,
      final Set<SourceName> withQuerySources
  ) {
    return execute(sql, ddlCommand, withQuery, withQuerySources, false);
  }
@Test
  public void shouldThrowOnMismatchedDatasourceType() {
    // Given:
    alterSource = new AlterSourceCommand(EXISTING_STREAM, DataSourceType.KTABLE.getKsqlType(), NEW_COLUMNS);

    // When:
    final KsqlException e = assertThrows(KsqlException.class,
        () -> cmdExec.execute(SQL_TEXT, alterSource, false, NO_QUERY_SOURCES));

    // Then:
    assertThat(e.getMessage(), is("Incompatible data source type is STREAM, but statement was ALTER TABLE"));
  }