Allow to specify diff paths

lib/gitlab_git/compare.rb

@@ -7,26 +7,28 @@ def initialize(repository, from, to, limit = 100)
         @commits, @diffs = [], []
         @commit = nil
         @same = false
+        @limit = limit
+        @repository = repository
 
         return unless from && to
 
-        base = Gitlab::Git::Commit.find(repository, from.try(:strip))
-        head = Gitlab::Git::Commit.find(repository, to.try(:strip))
+        @base = Gitlab::Git::Commit.find(repository, from.try(:strip))
+        @head = Gitlab::Git::Commit.find(repository, to.try(:strip))
 
-        return unless base && head
+        return unless @base && @head
 
-        if base.id == head.id
+        if @base.id == @head.id
           @same = true
           return
         end
 
-        @commit = head
-        @commits = Gitlab::Git::Commit.between(repository, base.id, head.id)
-        @diffs = if @commits.size > limit
-                   []
-                 else
-                   Gitlab::Git::Diff.between(repository, head.id, base.id) rescue []
-                 end
+        @commit = @head
+        @commits = Gitlab::Git::Commit.between(repository, @base.id, @head.id)
+      end
+
+      def diffs(paths = nil)
+        return [] if @commits.size > @limit
+        Gitlab::Git::Diff.between(@repository, @head.id, @base.id, *paths) rescue []
       end
     end
   end

lib/gitlab_git/diff.rb

@@ -15,13 +15,13 @@ class Diff
       attr_accessor  :new_file, :renamed_file, :deleted_file
 
       class << self
-        def between(repo, head, base)
+        def between(repo, head, base, *paths)
           # Only show what is new in the source branch compared to the target branch, not the other way around.
           # The linex below with merge_base is equivalent to diff with three dots (git diff branch1...branch2)
           # From the git documentation: "git diff A...B" is equivalent to "git diff $(git-merge-base A B) B"
           common_commit = repo.merge_base_commit(head, base)
 
-          repo.diff(common_commit, head).map do |diff|
+          repo.diff(common_commit, head, *paths).map do |diff|
             Gitlab::Git::Diff.new(diff)
           end
         rescue Grit::Git::GitTimeout

lib/gitlab_git/repository.rb

@@ -200,8 +200,8 @@ def merge_base_commit(from, to)
         grit.git.native(:merge_base, {}, [to, from]).strip
       end
 
-      def diff(from, to)
-        grit.diff(from, to)
+      def diff(from, to, *paths)
+        grit.diff(from, to, *paths)
       end
 
       # Returns commits collection