chore(package): lots of comments

packages/xo-server-test-plugin/index.js

@@ -1,17 +1,10 @@
-exports.default = function (opts) {
-  return {
-    configure: function (configuration) {
-      console.log('stub configured', configuration)
-    },
-    load: function () {
-      console.log('stub loaded')
-    },
-    unload: function () {
-      console.log('stub unloaded')
-    }
-  }
-}
+// This is one of the simplest xo-server's plugin than can be created.
 
+// This (optional) schema is used to describe the expected
+// configuration of the plugin.
+//
+// It will be used to generate a configuration UI (xo-web) and to
+// validate the provided configuration.
 exports.configurationSchema = {
   type: 'object',
   properties: {
@@ -21,3 +14,44 @@ exports.configurationSchema = {
   },
   required: ['foo']
 }
+
+// The default export is just a factory function which will create an
+// instance of the plugin.
+// Usually it will be called only once, at startup.
+//
+// Its only parameter is an object which currently only contains a
+// `xo` property: the instance of the currently running xo-server.
+exports.default = function (opts) {
+
+  // For simplicity's sake, this plugin returns a plain object, but
+  // usually it returns a new instance of an existing class.
+  return {
+
+    // This (optional) method is called each time the plugin is
+    // (re-)configured.
+    //
+    // Note: before being called, the configuration is validated
+    // against the provided configuration schema.
+    configure: function (configuration) {
+      console.log('stub configured', configuration)
+    },
+
+    // This method is called to load the plugin.
+    //
+    // Note 1: will only be called if the plugin is currently
+    // unloaded.
+    //
+    // Note 2: if the plugin is configurable, will only be called if
+    // the plugin has been successfully configured.
+    load: function () {
+      console.log('stub loaded')
+    },
+
+    // This (optional) method is called to unload the plugin.
+    //
+    // Note: will only be called if the plugin is currently loaded.
+    unload: function () {
+      console.log('stub unloaded')
+    }
+  }
+}