Use require.resolve to load fastify (#94)

Author: mcollina

plugin.js

@@ -3,6 +3,7 @@
 const semver = require('semver')
 const console = require('console')
 const extractPluginName = require('./stackParser')
+const { join, dirname } = require('path')
 
 function plugin (fn, options = {}) {
   if (typeof fn.default !== 'undefined') { // Support for 'export default' behaviour in transpiled ECMAScript module
@@ -58,7 +59,8 @@ function checkVersion (version, pluginName) {
 
   var fastifyVersion
   try {
-    fastifyVersion = semver.coerce(require('fastify/package.json').version)
+    const pkgPath = join(dirname(require.resolve('fastify', { paths: [require.main.filename] })), 'package.json')
+    fastifyVersion = semver.coerce(require(pkgPath).version)
   } catch (_) {
     console.info('fastify not found, proceeding anyway')
   }

test/test.js

@@ -5,6 +5,7 @@ const proxyquire = require('proxyquire')
 const test = t.test
 const fp = require('../plugin')
 const Fastify = require('fastify')
+const { join, normalize } = require('path')
 
 test('fastify-plugin is a function', t => {
   t.plan(1)
@@ -127,7 +128,7 @@ test('should not throw if fastify is not found', t => {
   t.plan(1)
 
   const fp = proxyquire('./../plugin.js', {
-    'fastify/package.json': null,
+    [normalize(join(__dirname, '..', 'node_modules', 'fastify', 'package.json'))]: null,
     console: {
       info: function (msg) {
         t.is(msg, 'fastify not found, proceeding anyway')