add node v9 & v10 in travis & appveyor

Author: erossignon

.travis.yml

@@ -17,6 +17,7 @@ env:
   #- TRAVIS_ELECTRON_VERSION="1.4.14" TRAVIS_NODE_VERSION="6"
   - TRAVIS_NODE_VERSION="8"
   - TRAVIS_NODE_VERSION="9"
+  - TRAVIS_NODE_VERSION="10"
 
 matrix:
   exclude:

appveyor.yml

@@ -36,6 +36,12 @@ environment:
     - nodejs_version: 8
       platform: x64
 
+    - nodejs_version: 9
+      platform: x64
+  
+    - nodejs_version: 10
+      platform: x64
+
     # - electron_version: "1.4.14"
     #   nodejs_version: 6
     #   platform: x86
@@ -57,7 +63,6 @@ environment:
     #   platform: x86
 
 
-
 # clone directory
 clone_folder: c:\projects\node-occ
 

test/helpers.js

@@ -11,6 +11,8 @@ const fs = require("fs");
 
 function remove_file(filename, optional_callback) {
 
+    optional_callback = optional_callback || function() {};
+
     fs.exists(filename, function (exists) {
 
         if (exists) {