### Question:
AggregationParameters { public void setPreparationId(String preparationId) { this.preparationId = preparationId; } AggregationParameters(); String getDatasetId(); void setDatasetId(String datasetId); String getPreparationId(); void setPreparationId(String preparationId); String getStepId(); void setStepId(String stepId); List<String> getGroupBy(); void setGroupBy(List<String> groupBy); void addGroupBy(String groupBy); String getFilter(); void setFilter(String filter); List<AggregationOperation> getOperations(); void setOperations(List<AggregationOperation> operations); void addOperation(AggregationOperation operation); Long getSampleSize(); void setSampleSize(String sampleSize); @Override String toString();  }### Answer:
@Test public void invalidParametersPreparationIdNoOperations() { AggregationParameters parameters = new AggregationParameters(); parameters.setPreparationId("prep#1234"); Set<ConstraintViolation<AggregationParameters>> constraintViolations = validator.validate(parameters); Assert.assertEquals(2, constraintViolations.size()); }