Developing plugins

Plugins

You can develop your own plugins for the Mocks Server to provide more interfaces, add more ways of defining fixtures, etc.

Naming plugins

It is recommended that plugins are published with the "mocks-server-plugin-[name]" name format in order to facilitate the search. Plugins should also contain the "mocks-server-plugin" tag in the package.json.

Plugins lifecycle

Plugins should contain four main methods, which will receive the instance of the Mocks Server core and a second argument with extra methods explicitly created for each different plugin. Please read the programmatic usage chapter to know how to interact with the core.

register(core, pluginMethods)

This method will be called for registering the plugin during the Mocks Server initialization, before options have been initialized.

Here you should register your own custom options using the core.addSetting method, register your own custom express routers using the core.addRouter method, etc.

You should never access here to the core.settings methods, are they are not still ready in this phase, which was designed with the intention of letting the plugins to add their own settings.

If you define your plugin as a Class, the constructor will be equivalent to defining a register method. If you define your plugin as a function, it will be called during the plugins registration, so you could also omit the register method.

init(core, pluginMethods)

This method will be called when Mocks Server settings are ready. Here you already can access to the core.settings to get the user options, and act in consequence. Here you should also add your listeners to the core events, such as core.onChangeSettings, core.onChangeMocks, etc.

start(core, pluginMethods)

When this method is called, the Mocks Server is already started and listening to requests, and the files watcher is observing for changes too.

stop(core, pluginMethods)

This method will be called when the Mocks Server stop method is called. Here you should stop all the plugin processes.

Plugins should also contain a displayName property or getter, which will be used by the core for debugging purposes.

Plugin methods

Apart of the core instance containing all methods and getters described in the programmatic usage chapter, plugins will receive methods explicitly created for each plugin instance as a second argument. This object contains next methods:

• loadMocks(definitions) - Loads "behaviors" and "fixtures" definitions. Each time this method is called, all previously loaded behaviors and fixtures will be replaced by the new ones, but only those added by this plugin. Definitions loaded by the core or by other plugins will remain.
  • definitions - <Array> Array containing fixtures or behaviors defined as described in the "fixtures" and "behaviors" chapters.
• addAlert(context, message, error) - Adds an alert, so mocks-server and other plugins can know about it. Use alerts to inform the user about deprecated methods or other warning messages, or about current errors. For example, when an error happens loading files, mocks-server adds automatically an alert in order to let the user know about the error.
  • context - <String> Use context to inform about different alerts contexts. Alerts are unique for each different context, so if you add another alert using the same context, the previous one will be removed. You can define different context levels (it is recommended to separate levels using :), as in deprecated:method, which is useful when using the removeAlerts method.
• removeAlerts([context]) - Removes alerts. All alerts starting by the provided context will be removed, so you can use context when adding alerts to define different levels that can be handled together. If no context is provided all alerts previously added by the plugin will be removed.

Example

Here you have an example of how a plugin is defined. Consult the Mocks Server programmatic usage chapter for further info:

class Plugin {
  constructor(core) {
    core.addSetting({
      name: "traceMocks",
      type: "boolean",
      description: "Trace mocks changes",
      default: true
    });

    this._core = core;
    this._onChangeMocks = this._onChangeMocks.bind(this);
    this._onChangeSettings = this._onChangeSettings.bind(this);
  }

  get displayName() {
    return "trace-mocks";
  }

  init(core) {
    this._enabled = core.settings.get("traceMocks");
    this._removeChangeMocksListener = core.onChangeMocks(this._onChangeMocks);
    this._removeChangeSettingsListener = core.onChangeSettings(this._onChangeSettings);
    core.tracer.debug(`traceMocks initial value is ${core.settings.get("traceMocks")}`);
  }

  traceBehaviors() {
    if (this._enabled && this._started) {
      this._core.tracer.info(`There are ${this._core.behaviors.count} behaviors available`);
    }
  }

  start(core) {
    this._started = true;
    core.tracer.debug("traceMocks plugin started");
    this.traceBehaviors();
  }

  stop(core) {
    this._started = false;
    core.tracer.debug("traceMocks plugin stopped");
  }

  _onChangeSettings(settings) {
    if (settings.hasOwnProperty("traceMocks")) {
      this._enabled = settings.traceMocks;
    }
  }

  _onChangeMocks() {
    this.traceBehaviors();
  }
}

module.exports = Plugin;

Plugins formats

The methods can be defined in a plain object, as methods of a Class or even using a function returning an object containing them.

Next examples show how each format should be defined:

Plugin as a Class

export default class Plugin {
  constructor(core, pluginMethods) {
    // Do your register stuff here
  }

  get displayName() {
    return "foo-plugin-name"
  }

  register(core, pluginMethods) {
    // You should omit this method if you already did your register stuff in the constructor
  }

  init(core, pluginMethods) {
    // Do your initialization stuff here
  }

  start(core, pluginMethods) {
    // Do your start stuff here
  }

  stop(core, pluginMethods) {
    // Do your stop stuff here
  }
}

Plugin as a function

const plugin = core => {
  // Do your register stuff here
  return {
    displayName: "foo-plugin-name",
    register: (core, pluginMethods) => {
      // You should omit this method if you already did your register stuff
    },
    init: (core, pluginMethods) => {
      // Do your initialization stuff here
    },
    start: (core, pluginMethods) => {
      // Do your start stuff here
    },
    stop: (core, pluginMethods) => {
      // Do your stop stuff here
    }
  };
};

export default plugin;

Plugin as an object

const plugin = {
  displayName: "foo-plugin-name",
  register: (core, pluginMethods) => {
    // Do your register stuff here
  },
  init: (core, pluginMethods) => {
    // Do your initialization stuff here
  },
  start: (core, pluginMethods) => {
    // Do your start stuff here
  },
  stop: (core, pluginMethods) => {
    // Do your stop stuff here
  }
};

export default plugin;

Adding plugins

Plugins can be added programmatically before the initialization of the server, or using the configuration file. Read the adding plugins chapter for further info.