suggestion: await engine to support inline engine import in options

.taprc

@@ -5,4 +5,4 @@ coverage: true
 nyc-arg: [--exclude=out]
 
 files:
-  - test/**/*.js
+  - test/**/*.{js,mjs}

index.js

@@ -32,7 +32,7 @@ async function fastifyView (fastify, opts) {
   }
   const charset = opts.charset || 'utf-8'
   const propertyName = opts.propertyName || 'view'
-  const engine = opts.engine[type]
+  const engine = await opts.engine[type]
   const globalOptions = opts.options || {}
   const templatesDir = resolveTemplateDir(opts)
   const includeViewExtension = opts.includeViewExtension || false

test/test-import-engine.mjs

@@ -0,0 +1,32 @@
+import t from 'tap'
+import get from 'simple-get'
+import Fastify from 'fastify'
+import fs from 'node:fs'
+const test = t.test
+const sget = get.concat
+
+test('using an imported engine as a promise', t => {
+  t.plan(3)
+  const fastify = Fastify()
+  const data = { text: 'text' }
+  const ejs = import('ejs')
+
+  fastify.register(import('../index.js'), { engine: { ejs }, templates: 'templates' })
+
+  fastify.get('/', (req, reply) => {
+    reply.view('index.ejs', data)
+  })
+
+  fastify.listen({ port: 0 }, err => {
+    t.error(err)
+
+    sget({
+      method: 'GET',
+      url: 'http://localhost:' + fastify.server.address().port
+    }, async (err, response, body) => {
+      t.error(err)
+      t.equal((await ejs).render(fs.readFileSync('./templates/index.ejs', 'utf8'), data), body.toString())
+      fastify.close()
+    })
+  })
+})