These two tests don't do anything. How about:

```
      it "should raise Chef::Exceptions::ValidationFailed on an attempt to set the guard_interpreter attribute to something other than a Symbol" do
        expect { resource.guard_interpreter('command_dot_com') }.to raise_error(Chef::Exceptions::ValidationFailed)
      end

      it "should not raise an exception when setting the guard interpreter attribute to a Symbol" do
        expect { resource.guard_interpreter(:command_dot_com) }.not_to raise_error(Chef::Exceptions::ValidationFailed)
      end
```