In IntelliJ IDEA:

1. Under File > Settings > Editor > Code style
2. Press 'Manage' button
3. Import GoogleStyle+Spock.xml file
4. Select 'Copy to project' to make it the project default

Also installing this IntelliJ IDEA plugin is recommended:
Spock Enhancements Plugin

1. Under File > Settings > Plugins
2. Press 'Browse repositories...' button
3. Search for 'spock'
4. Press 'Install' button