From efc1bf50dd9a8439f9dafae43ee340891c131792 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Sat, 8 Feb 2014 14:03:31 -0800
Subject: [PATCH] core: Machine#with_ui

---
 lib/vagrant/machine.rb            | 17 +++++++++++++++++
 test/unit/vagrant/machine_test.rb | 14 ++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/lib/vagrant/machine.rb b/lib/vagrant/machine.rb
index e0728aafb..3f084caba 100644
--- a/lib/vagrant/machine.rb
+++ b/lib/vagrant/machine.rb
@@ -1,3 +1,5 @@
+require "thread"
+
 require "log4r"
 
 module Vagrant
@@ -103,6 +105,7 @@ module Vagrant
       @provider_name   = provider_name
       @provider_options = provider_options
       @ui              = Vagrant::UI::Prefixed.new(@env.ui, @name)
+      @ui_mutex        = Mutex.new
 
       # Read the ID, which is usually in local storage
       @id = nil
@@ -337,5 +340,19 @@ module Vagrant
       raise Errors::MachineStateInvalid if !result.is_a?(MachineState)
       result
     end
+
+    # Temporarily changes the machine UI. This is useful if you want
+    # to execute an {#action} with a different UI.
+    def with_ui(ui)
+      @ui_mutex.synchronize do
+        begin
+          old_ui = @ui
+          @ui    = ui
+          yield
+        ensure
+          @ui = old_ui
+        end
+      end
+    end
   end
 end
diff --git a/test/unit/vagrant/machine_test.rb b/test/unit/vagrant/machine_test.rb
index 8e48dd511..1c723166f 100644
--- a/test/unit/vagrant/machine_test.rb
+++ b/test/unit/vagrant/machine_test.rb
@@ -445,4 +445,18 @@ describe Vagrant::Machine do
         to raise_error(Vagrant::Errors::MachineStateInvalid)
     end
   end
+
+  describe "#with_ui" do
+    it "temporarily changes the UI" do
+      ui = Object.new
+      changed_ui = nil
+
+      subject.with_ui(ui) do
+        changed_ui = subject.ui
+      end
+
+      expect(changed_ui).to equal(ui)
+      expect(subject.ui).to_not equal(ui)
+    end
+  end
 end