From f5e38a4a14daa7e2c792592913ea650237cb2dd8 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 6 Jul 2015 14:58:48 -0600
Subject: [PATCH] kernel/v2: not an error if synced folder guest path is empty
 [GH-4833]

---
 plugins/kernel_v2/config/vm.rb                | 18 ++++++++++--------
 test/unit/plugins/kernel_v2/config/vm_test.rb |  6 ++++++
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/plugins/kernel_v2/config/vm.rb b/plugins/kernel_v2/config/vm.rb
index 9f41ce184..d71dd0c17 100644
--- a/plugins/kernel_v2/config/vm.rb
+++ b/plugins/kernel_v2/config/vm.rb
@@ -603,16 +603,18 @@ module VagrantPlugins
           guestpath = Pathname.new(options[:guestpath])
           hostpath  = Pathname.new(options[:hostpath]).expand_path(machine.env.root_path)
 
-          if guestpath.relative? && guestpath.to_s !~ /^\w+:/
-            errors << I18n.t("vagrant.config.vm.shared_folder_guestpath_relative",
-                             path: options[:guestpath])
-          else
-            if used_guest_paths.include?(options[:guestpath])
-              errors << I18n.t("vagrant.config.vm.shared_folder_guestpath_duplicate",
+          if guestpath.to_s != ""
+            if guestpath.relative? && guestpath.to_s !~ /^\w+:/
+              errors << I18n.t("vagrant.config.vm.shared_folder_guestpath_relative",
                                path: options[:guestpath])
-            end
+            else
+              if used_guest_paths.include?(options[:guestpath])
+                errors << I18n.t("vagrant.config.vm.shared_folder_guestpath_duplicate",
+                                 path: options[:guestpath])
+              end
 
-            used_guest_paths.add(options[:guestpath])
+              used_guest_paths.add(options[:guestpath])
+            end
           end
 
           if !hostpath.directory? && !options[:create]
diff --git a/test/unit/plugins/kernel_v2/config/vm_test.rb b/test/unit/plugins/kernel_v2/config/vm_test.rb
index 50f185c9c..3d9b01213 100644
--- a/test/unit/plugins/kernel_v2/config/vm_test.rb
+++ b/test/unit/plugins/kernel_v2/config/vm_test.rb
@@ -480,6 +480,12 @@ describe VagrantPlugins::Kernel_V2::VMConfig do
       expect(sf["/vagrant"][:disabled]).to be_false
       expect(sf["/vagrant"][:foo]).to eq(:bar)
     end
+
+    it "is not an error if guest path is empty" do
+      subject.synced_folder(".", "")
+      subject.finalize!
+      assert_valid
+    end
   end
 
   describe "#usable_port_range" do