### Question:
Configuration { private Configuration() { try { init(); } catch (IOException ex) { throw new RuntimeException(ex); } } private  Configuration(); static Configuration getInstance(); void loadDefaults(ConfigDefaults[] configDefaults); void init(); Map<Object,Object> getProperties(); Map<Object, Object> getAllProperties(); String getStringProperty(Enum<? extends ConfigDefaults> name); String getStringProperty(String name); String getRawStringProperty(Enum<? extends ConfigDefaults> name); String getRawStringProperty(String name); boolean containsKey(String key); int getIntegerProperty(Enum<? extends ConfigDefaults> name); int getIntegerProperty(String name); static int intFromString(String value); float getFloatProperty(Enum<? extends ConfigDefaults> name); float getFloatProperty(String name); static float floatFromString(String value); long getLongProperty(Enum<? extends ConfigDefaults> name); long getLongProperty(String name); static long longFromString(String value); boolean getBooleanProperty(Enum<? extends ConfigDefaults> name); boolean getBooleanProperty(String name); static boolean booleanFromString(String value); List<String> getListProperty(Enum<? extends ConfigDefaults> name); List<String> getListProperty(String name); static List<String> stringListFromString(String value); void setProperty(String name, String val); void setProperty(Enum<? extends ConfigDefaults> name, String value); void clearProperty(String name); void clearProperty(Enum<? extends ConfigDefaults> name);  }### Answer:
@Test public void testConfiguration() { try { Configuration config = Configuration.getInstance(); Map<Object, Object> properties = config.getProperties(); Assert.assertNotNull(properties); Assert.assertEquals("127.0.0.1:19180", config.getStringProperty(CoreConfig.CASSANDRA_HOSTS)); System.setProperty("CASSANDRA_HOSTS", "127.0.0.2"); Assert.assertEquals("127.0.0.2", config.getStringProperty(CoreConfig.CASSANDRA_HOSTS)); Assert.assertEquals(60000, config.getIntegerProperty(CoreConfig.SCHEDULE_POLL_PERIOD)); } finally { System.clearProperty("CASSANDRA_HOSTS"); } }