Add basic unit test for CWD change warning

lib/vagrant/machine.rb

@@ -562,22 +562,23 @@ module Vagrant
       @data_dir.join("creator_uid")
     end
 
+    # Checks the current directory for a given machine
+    # and displays a warning if that machine has moved
+    # from its previous location on disk. If the machine
+    # has moved, it prints a warning to the user.
     def check_cwd
       vagrant_cwd_filepath = @data_dir.join('vagrant_cwd')
       vagrant_cwd = if File.exist?(vagrant_cwd_filepath)
         File.read(vagrant_cwd_filepath).chomp
       end
 
-      if vagrant_cwd
-        if vagrant_cwd != @env.cwd.to_s
+      if vagrant_cwd.nil?
+        File.write(vagrant_cwd_filepath, @env.cwd)
+      elsif vagrant_cwd != @env.cwd.to_s
         ui.warn(I18n.t(
           'vagrant.moved_cwd',
           old_wd:     vagrant_cwd,
           current_wd: @env.cwd.to_s))
-
-          File.write(vagrant_cwd_filepath, @env.cwd)
-        end
-      else
         File.write(vagrant_cwd_filepath, @env.cwd)
       end
     end

test/unit/vagrant/machine_test.rb

@@ -308,6 +308,23 @@ describe Vagrant::Machine do
         to raise_error(Vagrant::Errors::UnimplementedProviderAction)
     end
 
+    it 'should not warn if the machines cwd has not changed' do
+      initial_action_name  = :up
+      second_action_name  = :reload
+      callable     = lambda { |_env| }
+      original_cwd = env.cwd.to_s
+
+      allow(provider).to receive(:action).with(initial_action_name).and_return(callable)
+      allow(provider).to receive(:action).with(second_action_name).and_return(callable)
+      allow(subject.ui).to receive(:warn)
+
+      instance.action(initial_action_name)
+      expect(subject.ui).to_not have_received(:warn)
+
+      instance.action(second_action_name)
+      expect(subject.ui).to_not have_received(:warn)
+    end
+
     it 'should warn if the machine was last run under a different directory' do
       action_name  = :up
       callable     = lambda { |_env| }