Add test for validating git fetch.

lib/capistrano/deploy_tags.rb

@@ -2,11 +2,9 @@ module Capistrano
   module DeployTags
     def pending_git_changes?
       # Do we have any changes vs HEAD on deployment branch?
-      out = `git fetch 2>&1`
-      if $?.success?
-        ! (`git diff #{branch} --shortstat`.strip.empty?)
-      else
-        raise CommandError.new("git fetch failed:\n" + out)
+      `git fetch #{remote}`.tap do |output|
+        return !(`git diff #{branch} --shortstat`.strip.empty?) if exec_success?
+        raise "'git fetch #{remote}' failed:\n #{output}"
       end
     end
 
@@ -18,6 +16,10 @@ module Capistrano
       raise "#{args.join(" ")} failed!" unless system(*args)
     end
 
+    def exec_success?
+      $?.success?
+    end
+
     def validate_git_vars
       unless exists?(:branch) && exists?(:stage)
         logger.log Capistrano::Logger::IMPORTANT, 'Capistrano Deploytags requires that :branch and :stage be defined.'

spec/capistrano_deploy_tags_spec.rb

@@ -24,13 +24,21 @@ describe Capistrano::DeployTags do
   end
 
   context "prepare_tree" do
-    it "raises an error when not in a git tree" do
-      FileUtils.chdir '/tmp'
+    before :each do
       configuration.set(:branch, 'master')
       configuration.set(:stage, 'test')
+    end
+
+    it "raises an error when not in a git tree" do
+      FileUtils.chdir '/tmp'
       expect { configuration.find_and_execute_task('git:prepare_tree') }.to raise_error('git checkout master failed!')
     end
 
+    it "raises when unable to fetch" do
+      configuration.cdt.should_receive(:exec_success?).and_return(false)
+      expect { configuration.find_and_execute_task('git:prepare_tree') }.to raise_error(/'git fetch origin' failed/)
+    end
+
     context "with a clean git tree" do
       before :each do
         configuration.set(:branch, 'master')