### Question:
FilePluginManager implements PluginManager { @Override public AlertPlugin findOne(String pluginId) { return pluginMap.get(pluginId); } FilePluginManager(String dirPath, String[] whitePrefixes, String[] excludePrefixes); @Override AlertPlugin findOne(String pluginId); @Override Map<String, AlertPlugin> findAll(); @Override void addPlugin(AlertPlugin plugin);  }### Answer:
@Test public void findOne() { filePluginManager.addPlugin(alertPlugin); assertEquals(alertPlugin, filePluginManager.findOne(alertPlugin.getId())); }