Fixes #10869: Remove excludes if array is empty

Prior to this commit, if a user specified that their `rsync__excludes`
option was an empty array, Vagrant would treat that as if it included
options inside the array rather than ignoring it. This commit fixes that
by only adding the excludes option when it exists and is not empty.

plugins/synced_folders/rsync/default_unix_cap.rb

@@ -29,7 +29,7 @@ module VagrantPlugins
 
       def build_rsync_chown(opts)
         guest_path = Shellwords.escape(opts[:guestpath])
-        if(opts[:exclude])
+        if(opts[:exclude] && !Array(opts[:exclude]).empty?)
           exclude_base = Pathname.new(opts[:guestpath])
           exclusions = Array(opts[:exclude]).map do |ex_path|
             ex_path = ex_path.slice(1, ex_path.size) if ex_path.start_with?(File::SEPARATOR)

test/unit/plugins/synced_folders/rsync/default_unix_cap_test.rb

@@ -0,0 +1,87 @@
+require_relative "../../../base"
+
+require Vagrant.source_root.join("plugins/synced_folders/rsync/default_unix_cap")
+
+describe VagrantPlugins::SyncedFolderRSync::DefaultUnixCap do
+  include_context "unit"
+
+  let(:iso_env) do
+    # We have to create a Vagrantfile so there is a root path
+    env = isolated_environment
+    env.vagrantfile("")
+    env.create_vagrant_env
+  end
+
+  let(:guest)   { double("guest") }
+  let(:machine) { iso_env.machine(iso_env.machine_names[0], :dummy) }
+
+  let(:subject) { Class.new { extend VagrantPlugins::SyncedFolderRSync::DefaultUnixCap } }
+
+  describe "#rsync_installed" do
+    it "tests if rsync is on the path" do
+      expect(machine.communicate).to receive(:test).with("which rsync").
+        and_return(true)
+
+      subject.rsync_installed(machine)
+    end
+  end
+
+
+  describe "#rsync_command" do
+    it "returns the rsync command" do
+      expect( subject.rsync_command(machine) ).to eq("sudo rsync")
+    end
+  end
+
+  describe "#rsync_post" do
+    let(:opts) {{:type=>:rsync,
+                 :guestpath=>"/vagrant",
+                 :hostpath=>"/home/user/syncfolder",
+                 :disabled=>false,
+                 :__vagrantfile=>true,
+                 :exclude=>[".vagrant"],
+                 :owner=>"vagrant",
+                 :group=>"vagrant"}}
+
+    let(:cmd) { "find /vagrant -path /vagrant/.vagrant -prune -o '!' -type l -a '(' ! -user vagrant -or ! -group vagrant ')' -exec chown vagrant:vagrant '{}' +" }
+
+    it "executes the rsync post command" do
+      expect(machine.communicate).to receive(:sudo).
+        with(cmd)
+      subject.rsync_post(machine, opts)
+    end
+  end
+
+  describe "#build_rsync_chown" do
+    let(:opts) {{:type=>:rsync,
+                 :guestpath=>"/vagrant",
+                 :hostpath=>"/home/user/syncfolder",
+                 :disabled=>false,
+                 :__vagrantfile=>true,
+                 :exclude=>[".vagrant"],
+                 :owner=>"vagrant",
+                 :group=>"vagrant"}}
+
+    let(:cmd) { "find /vagrant -path /vagrant/.vagrant -prune -o '!' -type l -a '(' ! -user vagrant -or ! -group vagrant ')' -exec chown vagrant:vagrant '{}' +" }
+    let(:no_exclude_cmd) { "find /vagrant '!' -type l -a '(' ! -user vagrant -or ! -group vagrant ')' -exec chown vagrant:vagrant '{}' +" }
+
+    let(:empty_opts) {{:type=>:rsync,
+                 :guestpath=>"/vagrant",
+                 :hostpath=>"/home/user/syncfolder",
+                 :disabled=>false,
+                 :__vagrantfile=>true,
+                 :exclude=>[],
+                 :owner=>"vagrant",
+                 :group=>"vagrant"}}
+
+    it "builds up a command to properly chown folders" do
+      command = subject.build_rsync_chown(opts)
+      expect(command).to eq(cmd)
+    end
+
+    it "does not include any excludes if the array is empty" do
+      command = subject.build_rsync_chown(empty_opts)
+      expect(command).to eq(no_exclude_cmd)
+    end
+  end
+end