Regression unit test for frozen string literal fix (#1393)

Add a unit test for the prepare nfs settings action to act as a
regression test for the recent fix to avoiding modifying a frozen string
literal.

As part of this fix how the communicator is returned via a call to a
machine for testing purposes and remove an obsolete expect from the
wait till up tests as the code that would result in the communicator
being called has been removed.

Ensure that nfsd is not required to run the tests by mocking out the
host capability check.

lib/vagrant-libvirt/util/nfs.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'vagrant/action/builtin/mixin_synced_folders'
+
 module VagrantPlugins
   module ProviderLibvirt
     module Util

spec/support/sharedcontext.rb

@@ -36,6 +36,6 @@ shared_context 'unit' do
 
   before (:each) do
     allow(machine).to receive(:guest).and_return(guest)
-    allow(machine).to receive(:communicator).and_return(communicator)
+    allow(machine).to receive(:communicate).and_return(communicator)
   end
 end

spec/unit/action/prepare_nfs_settings_spec.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'support/sharedcontext'
+
+require 'vagrant-libvirt/action/prepare_nfs_settings'
+
+
+describe VagrantPlugins::ProviderLibvirt::Action::PrepareNFSSettings do
+  subject { described_class.new(app, env) }
+
+  include_context 'unit'
+
+  describe '#call' do
+    before do
+      # avoid requiring nfsd installed to run tests
+      allow(machine.env.host).to receive(:capability?).with(:nfs_installed).and_return(true)
+      allow(machine.env.host).to receive(:capability).with(:nfs_installed).and_return(true)
+    end
+
+    context 'when enabled' do
+      let(:vagrantfile) do
+        <<-EOF
+        Vagrant.configure('2') do |config|
+          config.vm.box = "vagrant-libvirt/test"
+          config.vm.define :test
+          config.vm.synced_folder ".", "/vagrant", type: "nfs"
+          config.vm.provider :libvirt do |libvirt|
+            #{vagrantfile_providerconfig}
+          end
+        end
+        EOF
+      end
+      let(:socket) { double('socket') }
+
+      before do
+        allow(::TCPSocket).to receive(:new).and_return(socket)
+        allow(socket).to receive(:close)
+      end
+
+      it 'should retrieve the guest IP address' do
+        times_called = 0
+        expect(::TCPSocket).to receive(:new) do
+          # force reaching later code
+          times_called += 1
+          times_called < 2 ? raise("StandardError") : socket
+        end
+        expect(machine).to receive(:ssh_info).and_return({:host => '192.168.1.2'})
+        expect(communicator).to receive(:execute).and_yield(:stdout, "192.168.1.2\n192.168.2.2")
+
+        expect(subject.call(env)).to be_nil
+      end
+    end
+  end
+end

spec/unit/action/wait_till_up_spec.rb

@@ -62,7 +62,6 @@ describe VagrantPlugins::ProviderLibvirt::Action::WaitTillUp do
           expect(app).to_not receive(:call)
           expect(ui).to receive(:info).with('Waiting for domain to get an IP address...')
           expect(ui).to_not receive(:info).with('Waiting for SSH to become available...')
-          expect(env[:machine].communicate).to_not receive(:ready?)
           expect {subject.call(env) }.to raise_error(::Fog::Errors::TimeoutError)
         end
       end