inspec/test/unit/mock/config_dirs/test-fixture-1-float

This test fixture is a user config dir setup as though the inspec-test-fixture v1 was already installed, and it has no version constraint.

This was accomplished by executing (without bundler) the following commands:

mkdir -p test/unit/mock/config_dirs/test-fixture-1-float/gems/{2.3.0,2.4.0,2.5.0}
# Here I'm running a ruby 2.4.x binary with rbenv
gem install -l -N -i test/unit/mock/config_dirs/test-fixture-1-float/gems/2.4.0 test/unit/mock/plugins/inspec-test-fixture/pkg/inspec-test-fixture-0.1.0.gem

Note that we will need to add an installation tree each time we support a new minor or major version of the Ruby VM.