Add Gitaly diff stats RPC client

This adds a basic interface to fetch diff statistics given two SHAs.
It's a requirement for #49399 #20282 and #19232.

2 files changed, 42 insertions, 0 deletions

diff --git a/spec/lib/gitlab/git/repository_spec.rb b/spec/lib/gitlab/git/repository_spec.rb
index 28c34e234f7..f89e3f70a78 100644
--- a/spec/lib/gitlab/git/repository_spec.rb
+++ b/spec/lib/gitlab/git/repository_spec.rb
@@ -1229,6 +1229,32 @@ describe Gitlab::Git::Repository, :seed_helper do
     end
   end
 
+  describe '#diff_stats' do
+    let(:left_commit_id) { 'feature' }
+    let(:right_commit_id) { 'master' }
+
+    it 'returns a DiffStatsCollection' do
+      collection = repository.diff_stats(left_commit_id, right_commit_id)
+
+      expect(collection).to be_a(Gitlab::Git::DiffStatsCollection)
+      expect(collection).to be_a(Enumerable)
+    end
+
+    it 'yields Gitaly::DiffStats objects' do
+      collection = repository.diff_stats(left_commit_id, right_commit_id)
+
+      expect(collection.to_a).to all(be_a(Gitaly::DiffStats))
+    end
+
+    it 'returns no Gitaly::DiffStats when SHAs are invalid' do
+      collection = repository.diff_stats('foo', 'bar')
+
+      expect(collection).to be_a(Gitlab::Git::DiffStatsCollection)
+      expect(collection).to be_a(Enumerable)
+      expect(collection.to_a).to be_empty
+    end
+  end
+
   describe "#ls_files" do
     let(:master_file_paths) { repository.ls_files("master") }
     let(:utf8_file_paths) { repository.ls_files("ls-files-utf8") }
diff --git a/spec/lib/gitlab/gitaly_client/commit_service_spec.rb b/spec/lib/gitlab/gitaly_client/commit_service_spec.rb
index bcdf12a00a0..d7bd757149d 100644
--- a/spec/lib/gitlab/gitaly_client/commit_service_spec.rb
+++ b/spec/lib/gitlab/gitaly_client/commit_service_spec.rb
@@ -118,6 +118,22 @@ describe Gitlab::GitalyClient::CommitService do
     end
   end
 
+  describe '#diff_stats' do
+    let(:left_commit_id) { 'master' }
+    let(:right_commit_id) { 'cfe32cf61b73a0d5e9f13e774abde7ff789b1660' }
+
+    it 'sends an RPC request' do
+      request = Gitaly::DiffStatsRequest.new(repository: repository_message,
+                                             left_commit_id: left_commit_id,
+                                             right_commit_id: right_commit_id)
+
+      expect_any_instance_of(Gitaly::DiffService::Stub).to receive(:diff_stats)
+        .with(request, kind_of(Hash)).and_return([])
+
+      described_class.new(repository).diff_stats(left_commit_id, right_commit_id)
+    end
+  end
+
   describe '#tree_entries' do
     let(:path) { '/' }