feat: synchronous plugin without callback (#265)

* feat: synchronous plugin without callback

* fix README.md

README.md

@@ -151,8 +151,6 @@ Loads one or more functions asynchronously.
 
 The function **must** have the signature: `instance, options, done`
 
-However, if the function returns a `Promise` (i.e. `async`), the above function signature is not required.
-
 Plugin example:
 ```js
 function plugin (server, opts, done) {
@@ -161,8 +159,11 @@ function plugin (server, opts, done) {
 
 app.use(plugin)
 ```
-`done` should be called only once, when your plugin is ready to go.  Additional
-calls to `done` are ignored.
+`done` should be called only once, when your plugin is ready to go.  Additional calls to `done` are ignored.
+
+If your plugin is ready to go immediately after the function is evaluated, you can omit `done` from the signature.
+
+If the function returns a `Promise` (i.e. `async`), the above function signature is not required.
 
 `use` returns a thenable wrapped instance on which `use` is called, to support a chainable API that can also be awaited.
 

lib/plugin.js

@@ -130,6 +130,8 @@ Plugin.prototype.exec = function (server, callback) {
     maybePromiseLike.then(
       () => process.nextTick(done),
       (e) => process.nextTick(done, e))
+  } else if (func.length < 3) {
+    done()
   }
 }
 

test/load-plugin.test.js

@@ -31,6 +31,17 @@ test('catch an error when loading a plugin with sync function', (t) => {
   })
 })
 
+test('successfully load a plugin with sync function without done as a parameter', (t) => {
+  t.plan(1)
+  const app = boot({})
+
+  const plugin = new Plugin(fastq(app, app._loadPluginNextTick, 1), function (instance, opts) { }, false, 0)
+
+  app._loadPlugin(plugin, function (err) {
+    t.equal(err, undefined)
+  })
+})
+
 test('successfully load a plugin with async function', (t) => {
   t.plan(1)
   const app = boot({})

test/no-done.test.js

@@ -0,0 +1,18 @@
+'use strict'
+
+const { test } = require('tap')
+const boot = require('..')
+
+test('not taking done does not throw error.', (t) => {
+  t.plan(2)
+
+  const app = boot()
+
+  app.use(noDone).ready((err) => {
+    t.notOk(err, 'no error')
+  })
+
+  function noDone (s, opts) {
+    t.pass('did not throw')
+  }
+})