inspec/test/fixtures/config_dirs/input_plugin/plugins.json

{
  "plugins_config_version" : "1.0.0",
  "plugins": [
    {
      "name": "inspec-input-test-fixture",
      "installation_type": "path",
      "installation_path": "test/fixtures/plugins/inspec-input-test-fixture/lib/inspec-input-test-fixture.rb"
    }
  ]
}