### Question:
XmlConfig extends Config { @Override public String getProperty(String key) { return (String) mConfiguration.getProperty(key); } XmlConfig();  XmlConfig(XmlConfig parent, HierarchicalConfiguration config);  XmlConfig(File file); @Override String getProperty(String key); @Override boolean getBoolean(String key, boolean defaultValue); @Override int getInt(String key, int defaultValue); @Override void setProperty(String key, String value); @Override boolean hasProperty(String key); @Override Config getSubconfig(String key); @Override U getComponent(Class<U> baseInterface); @Override U getComponent(String key, Class<U> baseInterface); @Override InputStream getNestedInputStream(String key); @Override OutputStream getNestedOutputStream(String key); @Override Collection<String> getCollection(String key); @Override void saveTo(OutputStream output);  }### Answer:
@Test public void testGetProperty() throws BadConfigException, FileNotFoundException { assertTrue(mConfig.hasProperty("test-property")); assertEquals("Hello world!", mConfig.getProperty("test-property")); }