Merge branch 'gitaly-fetch-remote' into 'master'

Add `Gitlab::Git::Repository#fetch` command

Closes gitaly#586

See merge request gitlab-org/gitlab-ce!14772

lib/gitlab/git/repository.rb

@@ -1086,6 +1086,12 @@ module Gitlab
         @has_visible_content = has_local_branches?
       end
+      def fetch(remote = 'origin')
+        args = %W(#{Gitlab.config.git.bin_path} fetch #{remote})
+
+        popen(args, @path).last.zero?
+      end
+
       def gitaly_repository
         Gitlab::GitalyClient::Util.repository(@storage, @relative_path, @gl_repository)
       end

spec/lib/gitlab/git/repository_spec.rb

@@ -1510,6 +1510,21 @@ describe Gitlab::Git::Repository, seed_helper: true do
     end
   end
+  describe '#fetch' do
+    let(:git_path) { Gitlab.config.git.bin_path }
+    let(:remote_name) { 'my_remote' }
+
+    subject { repository.fetch(remote_name) }
+
+    it 'fetches the remote and returns true if the command was successful' do
+      expect(repository).to receive(:popen)
+        .with(%W(#{git_path} fetch #{remote_name}), repository.path)
+        .and_return(['', 0])
+
+      expect(subject).to be(true)
+    end
+  end
+
   def create_remote_branch(repository, remote_name, branch_name, source_branch_name)
     source_branch = repository.branches.find { |branch| branch.name == source_branch_name }
     rugged = repository.rugged