### Question:
SimpleDataSource implements DataSource { @Override public boolean isWrapperFor(Class<?> iface) throws SQLException { return iface != null && iface.isAssignableFrom(getClass()); }  String getUrl(); void setUrl(String url); String getUser(); void setUser(String user); String getPassword(); void setPassword(String password); void addProperty(String key, String value); @Override int getLoginTimeout(); @Override void setLoginTimeout(int seconds); @Override Connection getConnection(); @Override Connection getConnection(String user, String password); @Override PrintWriter getLogWriter(); @Override void setLogWriter(PrintWriter out); @Override boolean isWrapperFor(Class<?> iface); @SuppressWarnings("unchecked") @Override T unwrap(Class<T> iface); Logger getParentLogger();  }### Answer:
@Test public void testIsWrapperFor() throws Exception { DataSource dataSource = new SimpleDataSource(); assertTrue(dataSource.isWrapperFor(SimpleDataSource.class)); assertFalse(dataSource.isWrapperFor(Runnable.class)); }