Could Vault.java please have these two constructors added? They allow MockBukkit to work and load the plugin as a dependency for others that you wish to test. In my case, I have Vault as a dependency for my plugin that I would like to test with MockBukkit.

public Vault()
    {
        super();
    }

    protected Vault(JavaPluginLoader loader, PluginDescriptionFile description, File dataFolder, File file)
    {
        super(loader, description, dataFolder, file);
    }

Thank you for your time and for considering this. Thanks!

MockBukkit should be made compatible with the built-in ways bukkit plugins are constructed, not force plugins to be made compatible with it.