### Question:
PropertiesUtil extends PropertyPlaceholderConfigurer { public static String[] getPropertyStringList(String key) { if (key == null) { return null; } String value = propertiesMap.get(key); if (value != null) { String[] splitValues = value.split(","); String[] returnValues = new String[splitValues.length]; for (int i = 0; i < splitValues.length; i++) { returnValues[i] = splitValues[i].trim(); } return returnValues; } else { return new String[0]; } } private  PropertiesUtil(); static String getProperty(String key, String defaultValue); static String getProperty(String key); static String[] getPropertyStringList(String key); static Integer getIntProperty(String key, int defaultValue); static Integer getIntProperty(String key); static boolean getBooleanProperty(String key, boolean defaultValue); static Map<String, String> getPropertiesMap(); static Properties getProps();  }### Answer:
@Test public void testGetPropertyStringList(){ String key = null; PropertiesUtil.getPropertyStringList(key); Assert.assertNull(key); }