Raise an error if the CWD is incorrect

lib/vagrant/environment.rb

@@ -59,6 +59,7 @@ module Vagrant
       opts[:cwd] ||= ENV["VAGRANT_CWD"] if ENV.has_key?("VAGRANT_CWD")
       opts[:cwd] ||= Dir.pwd
       opts[:cwd] = Pathname.new(opts[:cwd])
+      raise Errors::EnvironmentNonExistentCWD if !opts[:cwd].directory?
 
       # Set the Vagrantfile name up. We append "Vagrantfile" and "vagrantfile" so that
       # those continue to work as well, but anything custom will take precedence.

lib/vagrant/errors.rb

@@ -173,6 +173,11 @@ module Vagrant
       error_key(:status_error, "vagrant.downloaders.http")
     end
 
+    class EnvironmentNonExistentCWD < VagrantError
+      status_code(75)
+      error_key(:environment_non_existent_cwd)
+    end
+
     class EnvironmentLockedError < VagrantError
       status_code(52)
       error_key(:environment_locked)

test/unit/vagrant/environment_test.rb

@@ -17,13 +17,19 @@ describe Vagrant::Environment do
     end
 
     it "is set to the cwd given" do
-      instance = described_class.new(:cwd => "foobarbaz")
-      instance.cwd.should == Pathname.new("foobarbaz")
+      directory = File.dirname(__FILE__)
+      instance = described_class.new(:cwd => directory)
+      instance.cwd.should == Pathname.new(directory)
     end
 
     it "is set to the environmental variable VAGRANT_CWD" do
       pending "A good temporary ENV thing"
     end
+
+    it "raises an exception if the CWD doesn't exist" do
+      expect { described_class.new(:cwd => "doesntexist") }.
+        to raise_error(Vagrant::Errors::EnvironmentNonExistentCWD)
+    end
   end
 
   describe "home path" do