fix error messages (#3277)

lib/route.js

@@ -143,20 +143,21 @@ function buildRouting (options) {
       }
     }
 
+    const path = opts.url || opts.path
+
     if (!opts.handler) {
-      throw new Error(`Missing handler function for ${opts.method}:${opts.url} route.`)
+      throw new Error(`Missing handler function for ${opts.method}:${path} route.`)
     }
 
     if (opts.errorHandler !== undefined && typeof opts.errorHandler !== 'function') {
-      throw new Error(`Error Handler for ${opts.method}:${opts.url} route, if defined, must be a function`)
+      throw new Error(`Error Handler for ${opts.method}:${path} route, if defined, must be a function`)
     }
 
     validateBodyLimitOption(opts.bodyLimit)
 
     const prefix = this[kRoutePrefix]
 
     this.after((notHandledErr, done) => {
-      const path = opts.url || opts.path
       if (path === '/' && prefix.length && opts.method !== 'HEAD') {
         switch (opts.prefixTrailingSlash) {
           case 'slash':

test/route.test.js

@@ -1246,3 +1246,25 @@ test('Will not try to re-createprefixed HEAD route if it already exists and expo
 
   t.ok(true)
 })
+
+test('Correct error message is produced if "path" option is used', t => {
+  t.plan(2)
+
+  const fastify = Fastify()
+
+  t.throws(() => {
+    fastify.route({
+      method: 'GET',
+      path: '/test'
+    })
+  }, new Error('Missing handler function for GET:/test route.'))
+
+  t.throws(() => {
+    fastify.route({
+      method: 'POST',
+      url: '/test',
+      handler: function () {},
+      errorHandler: ''
+    })
+  }, new Error('Error Handler for POST:/test route, if defined, must be a function'))
+})