### Question:
StudyPresentation extends PresentationModel<Study> { public List<? extends Variable> getPopulationCharacteristics() { return getBean().getVariables(PopulationCharacteristic.class); } StudyPresentation(Study s, PresentationModelFactory pmf); StudyCharacteristicHolder getCharacteristicModel(Characteristic c); boolean isStudyFinished(); int getArmCount(); List<BasicArmPresentation> getArms(); int getPopulationCharacteristicCount(); List<? extends Variable> getPopulationCharacteristics(); LabeledPresentation getCharacteristicModel(BasicStudyCharacteristic c); List<OutcomeMeasure> getEndpoints(); List<OutcomeMeasure> getAdverseEvents(); PopulationCharTableModel getPopulationCharTableModel(); TableModel getEndpointTableModel(); TableModel getAdverseEventTableModel();  }### Answer:
@Test public void testGetPopulationCharacteristicsOverall() { PopulationCharacteristic age = new PopulationCharacteristic("Age", new ContinuousVariableType()); d_study.getPopulationChars().clear(); d_study.getPopulationChars().addAll(Study.wrapVariables(Collections.<PopulationCharacteristic>singletonList(age))); assertEquals(Collections.singletonList(age), d_model.getPopulationCharacteristics()); }