@Test
public void shouldUsedHeadPreparation() throws IOException {

    // Given
    final ExportParameters parameters = new ExportParameters();
    parameters.setExportType("JSON");
    parameters.setPreparationId("prep-1234");
    parameters.setStepId("head");
    final PreparationDTO preparation = new PreparationDTO();
    preparation.getSteps().add(Step.ROOT_STEP.id());
    preparation.setId("prep-1234");
    preparation.setHeadId("head");
    configurePreparation(preparation, "prep-1234", "head");
    // When
    final StreamingResponseBody body = strategy.execute(parameters);
    body.writeTo(new NullOutputStream());
    // Then
    final ArgumentCaptor<Configuration> captor = ArgumentCaptor.forClass(Configuration.class);
    verify(transformer).buildExecutable(any(), captor.capture());
    assertEquals("prep-1234", captor.getValue().getPreparationId());
    assertEquals("head", captor.getValue().getPreparation().getHeadId());
}