### Question:
WebDavMessage extends MimeMessage { @Override public void setFlag(Flag flag, boolean set) throws MessagingException { super.setFlag(flag, set); mFolder.setFlags(Collections.singletonList(this), Collections.singleton(flag), set); } WebDavMessage(String uid, Folder folder); void setUrl(String url); String getUrl(); void setSize(int size); void setFlagInternal(Flag flag, boolean set); void setNewHeaders(ParsedMessageEnvelope envelope); @Override void delete(String trashFolderName); @Override void setFlag(Flag flag, boolean set);  }### Answer:
@Test public void setFlag_asks_folder_to_set_flag() throws MessagingException { message.setFlag(Flag.FLAGGED, true); verify(mockFolder).setFlags(Collections.singletonList(message), Collections.singleton(Flag.FLAGGED), true); }