It's impossible to use the latest version of this gem:
In Gemfile:
test-kitchen
kitchen-inspec was resolved to 1.1.0, which depends on
test-kitchen (>= 1.6, < 3)
kitchen-nodes (~> 0.9.1) was resolved to 0.9.1, which depends on
test-kitchen (~> 1.13)
kitchen-vagrant was resolved to 1.5.2, which depends on
test-kitchen (>= 1.4, < 3)
Without setting a version, it installs the version 0.2.0.dev.1 which doesn't work with actual test-kitchen version.