First attempt on fetching

lib/multi_git/git_backend/remote.rb

@@ -37,6 +37,11 @@ def initialize( repo, url, push_url = url )
         @push_urls  = Array(push_url)
       end
 
+      def fetch(*refspecs)
+        rs = parse_fetch_refspec(*refspecs)
+        repository.__backend__['fetch',fetch_urls.first,*rs.map(&:to_s)]
+      end
+
     end
   end
 end

lib/multi_git/jgit_backend/remote.rb

@@ -27,6 +27,9 @@ def name
       FETCH_URL_KEY = 'url'.to_java
       PUSH_URL_KEY = 'pushurl'.to_java
 
+      FETCH = Java::OrgEclipseJgitTransport::Transport::Operation::FETCH
+      PUSH  = Java::OrgEclipseJgitTransport::Transport::Operation::PUSH
+
       def initialize( repository, url, push_url = url )
         @repository = repository
         conf = Java::OrgEclipseJgitLib::Config.new
@@ -44,10 +47,28 @@ def push_urls
         pu.any? ? pu : fetch_urls
       end
 
+      def fetch( *refspecs )
+        rs = parse_fetch_refspec(*refspecs).map{|refspec| Java::OrgEclipseJgitTransport::RefSpec.new(refspec.to_s) }
+        use_transport( FETCH ) do | transport |
+          transport.fetch( transport_monitor, rs )
+        end
+      end
+
     private
 
       attr :java_config
 
+      def use_transport( op )
+        tr = Java::OrgEclipseJgitTransport::Transport.open(repository.__backend__, java_config, op)
+        yield tr
+      ensure
+        tr.close
+      end
+
+      def transport_monitor
+        Java::OrgEclipseJgitLib::NullProgressMonitor::INSTANCE
+      end
+
     end
   end
 end

lib/multi_git/refspec.rb

@@ -34,6 +34,10 @@ def inspect
       ['#<',self.class,' ',forced ? '+':'',from,':',to,'>'].join
     end
 
+    def to_s
+      [forced ? '+':'',from,':',to].join
+    end
+
     class Parser
 
       REF = %r{\A(\+?)([a-zA-Z/0-9_*]+)?(?:(:)([a-zA-Z/0-9_*]+)?)?\z}

lib/multi_git/remote.rb

@@ -42,6 +42,23 @@ module Persistent
       #   @param name [String]
       #   @return [Persistent]
       abstract :save
+
+    protected
+
+      def refspec_parser
+        RefSpec::Parser.new("refs/remotes/#{name}/")
+      end
+
+    end
+
+  protected
+
+    def parse_fetch_refspec(*refspecs)
+      refspec_parser[*refspecs]
+    end
+
+    def refspec_parser
+      RefSpec::Parser.new("refs/remotes//")
     end
 
   end

lib/multi_git/rugged_backend/remote.rb

@@ -42,6 +42,19 @@ class Persistent < self
 
       end
 
+      def fetch(*refspecs)
+        rs = parse_fetch_refspec(*refspecs)
+        cl = Rugged::Remote.new(repository.__backend__, fetch_urls.first)
+        cl.clear_refspecs
+        rs.each do |spec|
+          cl.add_fetch(spec.to_s)
+        end
+        cl.connect(:fetch) do |r|
+          r.download
+        end
+        cl.update_tips!
+      end
+
     end
   end
 end

spec/shared/remote.rb

@@ -46,3 +46,54 @@
 
 end
 
+describe '#remote#fetch', remote: true do
+
+  let(:repository){ subject.open(tempdir, init: true) }
+
+  let(:remote_tempdir){ Dir.mktmpdir }
+
+  before(:each) do
+    remote = MultiGit.open(remote_tempdir, init:true, bare:true)
+    remote.branch('master').update do
+      MultiGit::Commit::Builder.new do
+        tree.file "foo", "bar"
+        at Time.new(2010,1,1,12,0,0)
+      end
+    end
+    remote['HEAD'].update do
+      remote.branch('master')
+    end
+  end
+
+  after(:each) do
+    FileUtils.rm_rf(remote_tempdir)
+  end
+
+  context 'by url' do
+
+    let(:remote){ repository.remote(remote_tempdir) }
+
+    it "can fetch stuff" do
+      remote.fetch('master:foo/master')
+      repository.branch('foo/master').target.oid.should == 'f1df07b6610bd7135015e8c00e7531f861f9c5bc'
+    end
+
+  end
+
+  context 'by existing name' do
+
+    before(:each) do
+      `cd #{tempdir}; git init --bare ; git remote add origin #{remote_tempdir}`
+    end
+
+    let(:remote){ repository.remote('origin') }
+
+    it "can fetch stuff" do
+      remote.fetch('master')
+      repository.branch('origin/master').target.oid.should == 'f1df07b6610bd7135015e8c00e7531f861f9c5bc'
+    end
+
+  end
+
+end
+