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 shouldAlterStream() {
    // Given:
    alterSource = new AlterSourceCommand(EXISTING_STREAM, DataSourceType.KSTREAM.getKsqlType(), NEW_COLUMNS);

    // When:
    final DdlCommandResult result = cmdExec.execute(SQL_TEXT, alterSource, false, NO_QUERY_SOURCES);

    // Then:
    assertThat(result.isSuccess(), is(true));
    assertThat(metaStore.getSource(EXISTING_STREAM).getSchema().columns().size(), is(10));
    assertThat(metaStore.getSource(EXISTING_STREAM).getSqlExpression(), is("sqlexpression\nsome ksql"));
  }