core: MachineIndex valid test is better

lib/vagrant/machine_index.rb

@@ -444,10 +444,7 @@ module Vagrant
         end
 
         # Refresh the machine state
-        machine.state
-
-        # If the machine doesn't have an ID, it is invalid
-        return false if !machine.id
+        return false if machine.state.id == MachineState::NOT_CREATED_ID
 
         true
       end

test/unit/support/dummy_provider.rb

@@ -11,6 +11,26 @@ module VagrantTests
   end
 
   class DummyProvider < Vagrant.plugin("2", :provider)
-    # No-op
+    def initialize(machine)
+      @machine = machine
+    end
+
+    def state=(id)
+      state_file.open("w+") do |f|
+        f.write(id.to_s)
+      end
+    end
+
+    def state
+      state_id = :running
+      state_id = state_file.read.to_sym if state_file.file?
+      Vagrant::MachineState.new(state_id, state_id.to_s, state_id.to_s)
+    end
+
+    protected
+
+    def state_file
+      @machine.data_dir.join("dummy_state")
+    end
   end
 end

test/unit/vagrant/machine_index_test.rb

@@ -308,6 +308,12 @@ describe Vagrant::MachineIndex::Entry do
       expect(subject).to_not be_valid(env.home_path)
     end
 
+    it "should be invalid if machine is not created" do
+      machine.id = "foo"
+      machine.provider.state = Vagrant::MachineState::NOT_CREATED_ID
+      expect(subject).to_not be_valid(env.home_path)
+    end
+
     context "with another active machine" do
       let(:vagrantfile) do
         <<-VF