core: Machine updates state cache when querying state

lib/vagrant/machine.rb

@@ -378,6 +378,19 @@ module Vagrant
     def state
       result = @provider.state
       raise Errors::MachineStateInvalid if !result.is_a?(MachineState)
+
+      # Update our state cache if we have a UUID and an entry in the
+      # master index.
+      uuid = index_uuid
+      if uuid
+        entry = @env.machine_index.get(uuid)
+        if entry
+          entry.state = result.short_description
+          @env.machine_index.set(entry)
+          @env.machine_index.release(entry)
+        end
+      end
+
       result
     end
 

test/unit/vagrant/machine_test.rb

@@ -517,7 +517,7 @@ describe Vagrant::Machine do
     end
   end
 
-  describe "state" do
+  describe "#state" do
     it "should query state from the provider" do
       state = Vagrant::MachineState.new(:id, "short", "long")
 
@@ -530,6 +530,21 @@ describe Vagrant::Machine do
       expect { instance.state }.
         to raise_error(Vagrant::Errors::MachineStateInvalid)
     end
+
+    it "should save the state with the index" do
+      allow(provider).to receive(:machine_id_changed)
+      subject.id = "foo"
+
+      state = Vagrant::MachineState.new(:id, "short", "long")
+      expect(provider).to receive(:state).and_return(state)
+
+      subject.state
+
+      entry = env.machine_index.get(subject.index_uuid)
+      expect(entry).to_not be_nil
+      expect(entry.state).to eq("short")
+      env.machine_index.release(entry)
+    end
   end
 
   describe "#with_ui" do