public LogicalSchema resolve(final ExecutionStep<?> step, final LogicalSchema schema) {
    return Optional.ofNullable(HANDLERS.get(step.getClass()))
        .map(h -> h.handle(this, schema, step))
        .orElseThrow(() -> new IllegalStateException("Unhandled step class: " + step.getClass()));
  }
@Test
  public void shouldResolveSchemaForTableGroupByAnyKey() {
    // Given:
    final TableGroupBy<?> step = new TableGroupBy<>(
        PROPERTIES,
        tableSource,
        formats,
        ImmutableList.of(new UnqualifiedColumnReferenceExp(Optional.empty(), ORANGE_COL))
    );

    // When:
    final LogicalSchema result = resolver.resolve(step, SCHEMA);

    // Then:
    assertThat(result, is(LogicalSchema.builder()
        .keyColumn(ORANGE_COL, SqlTypes.INTEGER)
        .valueColumns(SCHEMA.value())
        .build()));
  }