ci(appveyor.yml): Squelch Growl-related spawn errors

Installed GfW package needed for Windows desktop notification support.

#3483

appveyor.yml

@@ -1,27 +1,72 @@
-platform:
-  - x64
+###
+### appveyor.yml
+###
+
+## General configuration
+version: '{build}'
+skip_commits:
+  message: /\[ci\s+skip\]/
+
+## Environment configuration
+shallow_clone: true
+clone_depth: 1
 environment:
   matrix:
     - nodejs_version: '10'
     - nodejs_version: '9'
     - nodejs_version: '8'
     - nodejs_version: '6'
+matrix:
+  fast_finish: true
 install:
+  ## Manual Growl install
+  - ps: Add-AppveyorMessage "Installing Growl..."
+  - ps: $exePath = "$($env:USERPROFILE)\GrowlInstaller.exe"
+  - ps: (New-Object Net.WebClient).DownloadFile('http://www.growlforwindows.com/gfw/downloads/GrowlInstaller.exe', $exePath)
+  - ps: mkdir C:\GrowlInstaller | out-null
+  - ps: 7z x $exePath -oC:\GrowlInstaller | out-null
+  - ps: cmd /c start /wait msiexec /i C:\GrowlInstaller\Growl_v2.0.msi /quiet
+  - ps: $env:path = "C:\Program Files (x86)\Growl for Windows;$env:path"
+  ## Node-related installs
+  - ps: Add-AppveyorMessage "Installing Node..."
+  - set PATH=%APPDATA%\npm;C:\MinGW\bin;%PATH%
   - ps: Install-Product node $env:nodejs_version x64
-  - set CI=true
-  - set PATH=%APPDATA%\npm;c:\MinGW\bin;%PATH%
+  - ps: Add-AppveyorMessage "Installing npm..."
   - npm install -g npm@^5
+  ## Mocha-related package installs
+  - ps: Add-AppveyorMessage "Installing Mocha dependencies..."
   - npm ci --ignore-scripts
-matrix:
-  fast_finish: true
-build: off
-version: '{build}'
-shallow_clone: true
-clone_depth: 1
+
+## Build configuration
+platform:
+  - x64
+build: script
+before_build:
+  ## Growl requires some time before it's ready to handle notifications
+  - ps: Start-Process -NoNewWindow Growl
+  - ps: Add-AppveyorMessage "Started Growl service..."
+  - ps: Start-Sleep -Milliseconds 2000
+build_script:
+  ## Placeholder command
+  - ps: Start-Sleep -Milliseconds 0
+  #- ps: Add-AppveyorMessage "Verify Growl responding..."
+  #- ps: growlnotify test
+
+## Test configuration
+before_test:
+  - set CI=true
 test_script:
+  - ps: Add-AppveyorMessage "Displaying version information"
   - node --version
   - npm --version
+  - ps: Add-AppveyorMessage "Running tests..."
   - npm start test.node
-skip_commits:
-  message: /\[ci\s+skip\]/
+  - ps: Add-AppveyorMessage "Done"
+
+## Notifications
+notifications:
+  - provider: Email
+    on_build_success: false
+    on_build_failure: false
+    on_build_status_changed: false