Make sure we always start in a microtick (#189)

Signed-off-by: Matteo Collina <hello@matteocollina.com>
Fixes: fastify/fastify#4125

boot.js

@@ -334,7 +334,7 @@ Boot.prototype.ready = function (func) {
       throw new AVV_ERR_CALLBACK_NOT_FN('ready', typeof func)
     }
     this._readyQ.push(func)
-    this.start()
+    queueMicrotask(this.start.bind(this))
     return
   }
 

test/await-use.test.js

@@ -270,3 +270,25 @@ test('await use - mix of same and future tick callbacks', async (t) => {
   record += 'ready'
   t.equal(record, 'plugin0|plugin1|plugin2|ready')
 })
+
+test('await use - fork the promise chain', { only: true }, (t) => {
+  t.plan(3)
+  const app = {}
+  boot(app, { autostart: false })
+
+  async function setup () {
+    let set = false
+    await app.use(async function plugin0 () {
+      t.pass('plugin0 init')
+      await sleep(500)
+      set = true
+    })
+    t.equal(set, true)
+  }
+  setup()
+
+  app.ready((err, done) => {
+    t.error(err)
+    done()
+  })
+})

test/chainable.test.js

@@ -63,7 +63,7 @@ test('chainable automatically binded', (t) => {
     expose[key] = 'muahah'
 
     boot(app, {
-      expose: expose
+      expose
     })
 
     t.end()