Added Repo#commit_deltas_from as a (fairly expensive and lazy) way of getting

the commits that differ between two different repositories

.gitignore

@@ -1 +1,2 @@
 pkg
+.DS_Store

lib/grit/repo.rb

@@ -209,6 +209,20 @@ module Grit
       Commit.find_all(self, id, options).first
     end
     
+    # Returns a list of commits that is in +other_repo+ but not in self
+    #
+    # Returns Grit::Commit[]
+    def commit_deltas_from(other_repo, ref = "master", other_ref = "master")
+      # TODO: we should be able to figure out the branch point, rather than
+      # rev-list'ing the whole thing
+      repo_refs       = self.git.rev_list({}, ref).strip.split("\n")
+      other_repo_refs = other_repo.git.rev_list({}, other_ref).strip.split("\n")
+      
+      (other_repo_refs - repo_refs).map do |ref|
+        Commit.find_all(other_repo, ref, {:max_count => 1}).first
+      end
+    end
+    
     # The Tree object for the given treeish reference
     #   +treeish+ is the reference (default 'master')
     #   +paths+ is an optional Array of directory paths to restrict the tree (deafult [])

test/fixtures/rev_list_delta_a

@@ -0,0 +1,8 @@
+e34590b7a2d186b3bb9a1170d02d52b36c791c78
+8977833d74f8681aa0d9a5e84b0dd3d81519774d
+6f5561530cb3a94e4c86454e84732197325be172
+ee419e04a961543444be6db66aef52e6e37936d6
+d845de9d438e1a249a0c2fcb778e8ea3b7e06cef
+0bba4a6c10060405a94d52533af2f9bdacd4f29c
+77711c0722964ead965e0ba2ee9ed4a03cb3d292
+501d23cac6dd911511f15d091ee031a15b90ebde

test/fixtures/rev_list_delta_b

@@ -0,0 +1,11 @@
+4c8124ffcf4039d292442eeccabdeca5af5c5017
+634396b2f541a9f2d58b00be1a07f0c358b999b3
+ab25fd8483882c3bda8a458ad2965d2248654335
+e34590b7a2d186b3bb9a1170d02d52b36c791c78
+8977833d74f8681aa0d9a5e84b0dd3d81519774d
+6f5561530cb3a94e4c86454e84732197325be172
+ee419e04a961543444be6db66aef52e6e37936d6
+d845de9d438e1a249a0c2fcb778e8ea3b7e06cef
+0bba4a6c10060405a94d52533af2f9bdacd4f29c
+77711c0722964ead965e0ba2ee9ed4a03cb3d292
+501d23cac6dd911511f15d091ee031a15b90ebde

test/test_repo.rb

@@ -318,4 +318,30 @@ class TestRepo < Test::Unit::TestCase
     Git.any_instance.expects(:log).with({:pretty => 'raw', :max_count => 1}, 'master', '--', 'file.rb').returns(fixture('rev_list'))
     @r.log('master', 'file.rb', :max_count => 1)
   end
+  
+  # commit_deltas_from
+  
+  def test_commit_deltas_from_nothing_new
+    other_repo = Repo.new(GRIT_REPO)
+    @r.git.expects(:rev_list).with({}, "master").returns(fixture("rev_list_delta_b"))
+    other_repo.git.expects(:rev_list).with({}, "master").returns(fixture("rev_list_delta_a"))
+    
+    delta_commits = @r.commit_deltas_from(other_repo)
+    assert_equal 0, delta_commits.size
+  end
+  
+  def test_commit_deltas_from_when_other_has_new
+    other_repo = Repo.new(GRIT_REPO)
+    @r.git.expects(:rev_list).with({}, "master").returns(fixture("rev_list_delta_a"))
+    other_repo.git.expects(:rev_list).with({}, "master").returns(fixture("rev_list_delta_b"))
+    %w[
+      4c8124ffcf4039d292442eeccabdeca5af5c5017
+      634396b2f541a9f2d58b00be1a07f0c358b999b3
+      ab25fd8483882c3bda8a458ad2965d2248654335
+    ].each do |ref|
+      Commit.expects(:find_all).with(other_repo, ref, :max_count => 1).returns([stub()])
+    end
+    delta_commits = @r.commit_deltas_from(other_repo)
+    assert_equal 3, delta_commits.size
+  end
 end