add option to encapsulate

README.md

@@ -96,6 +96,31 @@ module.exports = fp(plugin, {
 })
 ```
 
+#### Encapsulate
+You can optionally keep the plugin encapsulated, which is the default behavior if you weren't using `fastify-plugin`.
+This allows you to set the plugin's name and validate its dependencies without making the plugin accessible.
+Read more about encapsulation [here](https://github.com/fastify/fastify/blob/main/docs/Reference/Encapsulation.md).
+```js
+const fp = require('fastify-plugin')
+
+function plugin (fastify, opts, next) {
+  // the decorator is not accessible outside this plugin
+  fastify.decorate('util', function() {})
+  next()
+}
+
+module.exports = fp(plugin, {
+  name: 'my-encapsulated-plugin',
+  fastify: '4.x',
+  decorators: {
+    fastify: ['plugin1', 'plugin2'],
+    reply: ['compress']
+  },
+  dependencies: ['plugin1-name', 'plugin2-name'],
+  encapsulate: true
+})
+```
+
 #### Bundlers and Typescript
 `fastify-plugin` adds a `.default` and `[name]` property to the passed in function.
 The type definition would have to be updated to leverage this.

plugin.d.ts

@@ -65,7 +65,8 @@ export interface PluginMetadata {
     request?: (string | symbol)[]
   },
   /** The plugin dependencies */
-  dependencies?: string[]
+  dependencies?: string[],
+  encapsulate?: boolean
 }
 
 // Exporting PluginOptions for backward compatibility after renaming it to PluginMetadata

plugin.js

@@ -18,10 +18,6 @@ function plugin (fn, options = {}) {
     )
   }
 
-  fn[Symbol.for('skip-override')] = true
-
-  const pluginName = (options && options.name) || checkName(fn)
-
   if (typeof options === 'string') {
     options = {
       fastify: options
@@ -42,9 +38,10 @@ function plugin (fn, options = {}) {
 
   if (!options.name) {
     autoName = true
-    options.name = pluginName + '-auto-' + count++
+    options.name = checkName(fn) + '-auto-' + count++
   }
 
+  fn[Symbol.for('skip-override')] = options.encapsulate !== true
   fn[Symbol.for('fastify.display-name')] = options.name
   fn[Symbol.for('plugin-meta')] = options
 

plugin.test-d.ts

@@ -29,7 +29,8 @@ expectAssignable<FastifyPluginCallback>(fp(pluginCallback, {
     reply: [ '', testSymbol ],
     request: [ '', testSymbol ]
   },
-  dependencies: [ '' ]
+  dependencies: [ '' ],
+  encapsulate: true
 }))
 
 const pluginCallbackWithOptions: FastifyPluginCallback<Options> = (fastify, options, next) => {
@@ -66,7 +67,8 @@ expectAssignable<FastifyPluginAsync>(fp(pluginAsync, {
     reply: [ '', testSymbol ],
     request: [ '', testSymbol ]
   },
-  dependencies: [ '' ]
+  dependencies: [ '' ],
+  encapsulate: true
 }))
 
 const pluginAsyncWithOptions: FastifyPluginAsync<Options> = async (fastify, options) => {

test/test.js

@@ -237,3 +237,38 @@ test('should check fastify dependency graph - decorateReply', t => {
     t.equal(err.message, "The decorator 'plugin2' required by 'test' is not present in Reply")
   })
 })
+
+test('should accept an option to encapsulate', t => {
+  t.plan(4)
+  const fastify = Fastify()
+
+  fastify.register(fp((fastify, opts, next) => {
+    fastify.decorate('accessible', true)
+    next()
+  }, {
+    name: 'accessible-plugin'
+  }))
+
+  fastify.register(fp((fastify, opts, next) => {
+    fastify.decorate('alsoAccessible', true)
+    next()
+  }, {
+    name: 'accessible-plugin2',
+    encapsulate: false
+  }))
+
+  fastify.register(fp((fastify, opts, next) => {
+    fastify.decorate('encapsulated', true)
+    next()
+  }, {
+    name: 'encapsulated-plugin',
+    encapsulate: true
+  }))
+
+  fastify.ready(err => {
+    t.notOk(err)
+    t.ok(fastify.hasDecorator('accessible'))
+    t.ok(fastify.hasDecorator('alsoAccessible'))
+    t.notOk(fastify.hasDecorator('encapsulated'))
+  })
+})