Add latest changes from gitlab-org/gitlab@13-2-stable-ee

27 files changed, 361 insertions, 26 deletions

diff --git a/spec/lib/gitlab/diff/diff_refs_spec.rb b/spec/lib/gitlab/diff/diff_refs_spec.rb
index 33a7cf5ae12..c1ee34ba874 100644
--- a/spec/lib/gitlab/diff/diff_refs_spec.rb
+++ b/spec/lib/gitlab/diff/diff_refs_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::DiffRefs do
+RSpec.describe Gitlab::Diff::DiffRefs do
   let(:project) { create(:project, :repository) }
 
   describe '#==' do
diff --git a/spec/lib/gitlab/diff/file_collection/commit_spec.rb b/spec/lib/gitlab/diff/file_collection/commit_spec.rb
index 34ed22b8941..6c109e96a53 100644
--- a/spec/lib/gitlab/diff/file_collection/commit_spec.rb
+++ b/spec/lib/gitlab/diff/file_collection/commit_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::FileCollection::Commit do
+RSpec.describe Gitlab::Diff::FileCollection::Commit do
   let(:project) { create(:project, :repository) }
 
   it_behaves_like 'diff statistics' do
diff --git a/spec/lib/gitlab/diff/file_collection/compare_spec.rb b/spec/lib/gitlab/diff/file_collection/compare_spec.rb
index f330f299ac1..168d58e584e 100644
--- a/spec/lib/gitlab/diff/file_collection/compare_spec.rb
+++ b/spec/lib/gitlab/diff/file_collection/compare_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::FileCollection::Compare do
+RSpec.describe Gitlab::Diff::FileCollection::Compare do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/file_collection/merge_request_diff_batch_spec.rb b/spec/lib/gitlab/diff/file_collection/merge_request_diff_batch_spec.rb
index 7e945d1d140..bd60c24859c 100644
--- a/spec/lib/gitlab/diff/file_collection/merge_request_diff_batch_spec.rb
+++ b/spec/lib/gitlab/diff/file_collection/merge_request_diff_batch_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::FileCollection::MergeRequestDiffBatch do
+RSpec.describe Gitlab::Diff::FileCollection::MergeRequestDiffBatch do
   let(:merge_request) { create(:merge_request) }
   let(:batch_page) { 1 }
   let(:batch_size) { 10 }
diff --git a/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb b/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb
index c2b6ca4164c..a5e714c90fc 100644
--- a/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb
+++ b/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::FileCollection::MergeRequestDiff do
+RSpec.describe Gitlab::Diff::FileCollection::MergeRequestDiff do
   let(:merge_request) { create(:merge_request) }
   let(:diffable) { merge_request.merge_request_diff }
   let(:subject) { described_class.new(diffable, diff_options: nil) }
diff --git a/spec/lib/gitlab/diff/file_spec.rb b/spec/lib/gitlab/diff/file_spec.rb
index 8dbedcf26b9..94abfcf079a 100644
--- a/spec/lib/gitlab/diff/file_spec.rb
+++ b/spec/lib/gitlab/diff/file_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::File do
+RSpec.describe Gitlab::Diff::File do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb b/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb
index 3f88f39ba92..579776d44aa 100644
--- a/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb
+++ b/spec/lib/gitlab/diff/formatters/image_formatter_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Formatters::ImageFormatter do
+RSpec.describe Gitlab::Diff::Formatters::ImageFormatter do
   let(:base_attrs) do
     {
       base_sha: 123,
diff --git a/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb b/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb
index 50dd597c5a7..41877a16ebf 100644
--- a/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb
+++ b/spec/lib/gitlab/diff/formatters/text_formatter_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Formatters::TextFormatter do
+RSpec.describe Gitlab::Diff::Formatters::TextFormatter do
   let!(:base) do
     {
       base_sha: 123,
diff --git a/spec/lib/gitlab/diff/highlight_cache_spec.rb b/spec/lib/gitlab/diff/highlight_cache_spec.rb
index 3c128aad976..80cc10051c4 100644
--- a/spec/lib/gitlab/diff/highlight_cache_spec.rb
+++ b/spec/lib/gitlab/diff/highlight_cache_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::HighlightCache, :clean_gitlab_redis_cache do
+RSpec.describe Gitlab::Diff::HighlightCache, :clean_gitlab_redis_cache do
   let(:merge_request) { create(:merge_request_with_diffs) }
   let(:diff_hash) do
     { ".gitignore-false-false-false" =>
diff --git a/spec/lib/gitlab/diff/highlight_spec.rb b/spec/lib/gitlab/diff/highlight_spec.rb
index ff4ec75358e..283437e7fbd 100644
--- a/spec/lib/gitlab/diff/highlight_spec.rb
+++ b/spec/lib/gitlab/diff/highlight_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Highlight do
+RSpec.describe Gitlab::Diff::Highlight do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/inline_diff_markdown_marker_spec.rb b/spec/lib/gitlab/diff/inline_diff_markdown_marker_spec.rb
index a668bb464a4..60f7f3a103f 100644
--- a/spec/lib/gitlab/diff/inline_diff_markdown_marker_spec.rb
+++ b/spec/lib/gitlab/diff/inline_diff_markdown_marker_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::InlineDiffMarkdownMarker do
+RSpec.describe Gitlab::Diff::InlineDiffMarkdownMarker do
   describe '#mark' do
     let(:raw) { "abc 'def'" }
     let(:inline_diffs) { [2..5] }
diff --git a/spec/lib/gitlab/diff/inline_diff_marker_spec.rb b/spec/lib/gitlab/diff/inline_diff_marker_spec.rb
index 26b99870b31..6820a7df95e 100644
--- a/spec/lib/gitlab/diff/inline_diff_marker_spec.rb
+++ b/spec/lib/gitlab/diff/inline_diff_marker_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::InlineDiffMarker do
+RSpec.describe Gitlab::Diff::InlineDiffMarker do
   describe '#mark' do
     let(:inline_diffs) { [2..5] }
     let(:raw) { "abc 'def'" }
diff --git a/spec/lib/gitlab/diff/inline_diff_spec.rb b/spec/lib/gitlab/diff/inline_diff_spec.rb
index fdbee3b4230..35284e952f7 100644
--- a/spec/lib/gitlab/diff/inline_diff_spec.rb
+++ b/spec/lib/gitlab/diff/inline_diff_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::InlineDiff do
+RSpec.describe Gitlab::Diff::InlineDiff do
   describe '.for_lines' do
     let(:diff) do
       <<-EOF.strip_heredoc
diff --git a/spec/lib/gitlab/diff/line_mapper_spec.rb b/spec/lib/gitlab/diff/line_mapper_spec.rb
index 6a86f885c3b..1c1f8201a81 100644
--- a/spec/lib/gitlab/diff/line_mapper_spec.rb
+++ b/spec/lib/gitlab/diff/line_mapper_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::LineMapper do
+RSpec.describe Gitlab::Diff::LineMapper do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/line_spec.rb b/spec/lib/gitlab/diff/line_spec.rb
index 7961bec9d57..e10a50afde9 100644
--- a/spec/lib/gitlab/diff/line_spec.rb
+++ b/spec/lib/gitlab/diff/line_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Line do
+RSpec.describe Gitlab::Diff::Line do
   shared_examples 'line object initialized by hash' do
     it 'round-trips correctly with to_hash' do
       expect(described_class.safe_init_from_hash(line.to_hash).to_hash)
diff --git a/spec/lib/gitlab/diff/lines_unfolder_spec.rb b/spec/lib/gitlab/diff/lines_unfolder_spec.rb
index ebcbe1fb1a0..b891f9e8285 100644
--- a/spec/lib/gitlab/diff/lines_unfolder_spec.rb
+++ b/spec/lib/gitlab/diff/lines_unfolder_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::LinesUnfolder do
+RSpec.describe Gitlab::Diff::LinesUnfolder do
   let(:raw_diff) do
     <<-DIFF.strip_heredoc
       @@ -7,9 +7,6 @@
diff --git a/spec/lib/gitlab/diff/parallel_diff_spec.rb b/spec/lib/gitlab/diff/parallel_diff_spec.rb
index d275bf2c223..f574d7ec707 100644
--- a/spec/lib/gitlab/diff/parallel_diff_spec.rb
+++ b/spec/lib/gitlab/diff/parallel_diff_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::ParallelDiff do
+RSpec.describe Gitlab::Diff::ParallelDiff do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/parser_spec.rb b/spec/lib/gitlab/diff/parser_spec.rb
index 00a446c4e20..7448ae0b2ea 100644
--- a/spec/lib/gitlab/diff/parser_spec.rb
+++ b/spec/lib/gitlab/diff/parser_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Parser do
+RSpec.describe Gitlab::Diff::Parser do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/position_collection_spec.rb b/spec/lib/gitlab/diff/position_collection_spec.rb
index dd8434ab10b..b1478c774f1 100644
--- a/spec/lib/gitlab/diff/position_collection_spec.rb
+++ b/spec/lib/gitlab/diff/position_collection_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::PositionCollection do
+RSpec.describe Gitlab::Diff::PositionCollection do
   let(:merge_request) { build(:merge_request) }
 
   let(:text_position) do
diff --git a/spec/lib/gitlab/diff/position_spec.rb b/spec/lib/gitlab/diff/position_spec.rb
index b32a2c59bb9..a7f6ea0cbfb 100644
--- a/spec/lib/gitlab/diff/position_spec.rb
+++ b/spec/lib/gitlab/diff/position_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Position do
+RSpec.describe Gitlab::Diff::Position do
   include RepoHelpers
 
   let(:project) { create(:project, :repository) }
diff --git a/spec/lib/gitlab/diff/position_tracer/image_strategy_spec.rb b/spec/lib/gitlab/diff/position_tracer/image_strategy_spec.rb
index 900816af53a..7dceb64b776 100644
--- a/spec/lib/gitlab/diff/position_tracer/image_strategy_spec.rb
+++ b/spec/lib/gitlab/diff/position_tracer/image_strategy_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::PositionTracer::ImageStrategy do
+RSpec.describe Gitlab::Diff::PositionTracer::ImageStrategy do
   include PositionTracerHelpers
 
   let(:project) { create(:project, :repository) }
@@ -234,5 +234,118 @@ describe Gitlab::Diff::PositionTracer::ImageStrategy do
         end
       end
     end
+
+    describe 'symlink scenarios' do
+      let(:new_file) { old_file_status == :new }
+      let(:deleted_file) { old_file_status == :deleted }
+      let(:renamed_file) { old_file_status == :renamed }
+
+      let(:file_identifier) { "#{file_name}-#{new_file}-#{deleted_file}-#{renamed_file}" }
+      let(:file_identifier_hash) { Digest::SHA1.hexdigest(file_identifier) }
+      let(:old_position) { position(old_path: file_name, new_path: file_name, position_type: 'image', file_identifier_hash: file_identifier_hash) }
+
+      let(:update_file_commit) do
+        initial_commit
+
+        update_file(
+          branch_name,
+          file_name,
+          Base64.encode64('morecontent')
+        )
+      end
+
+      let(:delete_file_commit) do
+        initial_commit
+
+        delete_file(branch_name, file_name)
+      end
+
+      let(:create_second_file_commit) do
+        initial_commit
+
+        create_file(
+          branch_name,
+          second_file_name,
+          Base64.encode64('morecontent')
+        )
+      end
+
+      before do
+        stub_feature_flags(file_identifier_hash: true)
+      end
+
+      describe 'from symlink to image' do
+        let(:initial_commit) { project.commit('a19c7f9a147e35e535c797cf148d29c24dac5544') }
+        let(:symlink_to_image_commit) { project.commit('8cfca8420812e5bd7479aa32cf33e0c95a3ca576') }
+        let(:branch_name) { 'diff-files-symlink-to-image' }
+        let(:file_name) { 'symlink-to-image.png' }
+
+        context "when the old position is on the new image file" do
+          let(:old_file_status) { :new }
+
+          context "when the image file's content was unchanged between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_image_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, create_second_file_commit) }
+
+            it "returns the new position" do
+              expect_new_position(
+                old_path: file_name,
+                new_path: file_name
+              )
+            end
+          end
+
+          context "when the image file's content was changed between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_image_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, update_file_commit) }
+            let(:change_diff_refs) { diff_refs(symlink_to_image_commit, update_file_commit) }
+
+            it "returns the position of the change" do
+              expect_change_position(
+                old_path: file_name,
+                new_path: file_name
+              )
+            end
+          end
+
+          context "when the image file was removed between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_image_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, delete_file_commit) }
+            let(:change_diff_refs) { diff_refs(symlink_to_image_commit, delete_file_commit) }
+
+            it "returns the position of the change" do
+              expect_change_position(
+                old_path: file_name,
+                new_path: file_name
+              )
+            end
+          end
+        end
+      end
+
+      describe 'from image to symlink' do
+        let(:initial_commit) { project.commit('d10dcdfbbb2b59a959a5f5d66a4adf28f0ea4008') }
+        let(:image_to_symlink_commit) { project.commit('3e94fdaa60da8aed38401b91bc56be70d54ca424') }
+        let(:branch_name) { 'diff-files-image-to-symlink' }
+        let(:file_name) { 'image-to-symlink.png' }
+
+        context "when the old position is on the added image file" do
+          let(:old_file_status) { :new }
+
+          context "when the image file gets changed to a symlink between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit.parent, initial_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit.parent, image_to_symlink_commit) }
+            let(:change_diff_refs) { diff_refs(initial_commit, image_to_symlink_commit) }
+
+            it "returns the position of the change" do
+              expect_change_position(
+                old_path: file_name,
+                new_path: file_name
+              )
+            end
+          end
+        end
+      end
+    end
   end
 end
diff --git a/spec/lib/gitlab/diff/position_tracer/line_strategy_spec.rb b/spec/lib/gitlab/diff/position_tracer/line_strategy_spec.rb
index 7f4902c5b86..d9f384fb47f 100644
--- a/spec/lib/gitlab/diff/position_tracer/line_strategy_spec.rb
+++ b/spec/lib/gitlab/diff/position_tracer/line_strategy_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::PositionTracer::LineStrategy do
+RSpec.describe Gitlab::Diff::PositionTracer::LineStrategy do
   # Douwe's diary                                    New York City, 2016-06-28
   # --------------------------------------------------------------------------
   #
@@ -1801,5 +1801,143 @@ describe Gitlab::Diff::PositionTracer::LineStrategy do
         end
       end
     end
+
+    describe 'symlink scenarios' do
+      let(:new_file) { old_file_status == :new }
+      let(:deleted_file) { old_file_status == :deleted }
+      let(:renamed_file) { old_file_status == :renamed }
+
+      let(:file_identifier) { "#{file_name}-#{new_file}-#{deleted_file}-#{renamed_file}" }
+      let(:file_identifier_hash) { Digest::SHA1.hexdigest(file_identifier) }
+
+      let(:update_line_commit) do
+        update_file(
+          branch_name,
+          file_name,
+          <<-CONTENT.strip_heredoc
+            A
+            BB
+            C
+          CONTENT
+        )
+      end
+
+      let(:delete_file_commit) do
+        delete_file(branch_name, file_name)
+      end
+
+      let(:create_second_file_commit) do
+        create_file(
+          branch_name,
+          second_file_name,
+          <<-CONTENT.strip_heredoc
+            D
+            E
+          CONTENT
+        )
+      end
+
+      before do
+        stub_feature_flags(file_identifier_hash: true)
+      end
+
+      describe 'from symlink to text' do
+        let(:initial_commit) { project.commit('0e5b363105e9176a77bac94d7ff6d8c4fb35c3eb') }
+        let(:symlink_to_text_commit) { project.commit('689815e617abc6889f1fded4834d2dd7d942a58e') }
+        let(:branch_name) { 'diff-files-symlink-to-text' }
+        let(:file_name) { 'symlink-to-text.txt' }
+        let(:old_position) { position(old_path: file_name, new_path: file_name, new_line: 3, file_identifier_hash: file_identifier_hash) }
+
+        before do
+          create_branch('diff-files-symlink-to-text-test', branch_name)
+        end
+
+        context "when the old position is on the new text file" do
+          let(:old_file_status) { :new }
+
+          context "when the text file's content was unchanged between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_text_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, create_second_file_commit) }
+
+            it "returns the new position" do
+              expect_new_position(
+                new_path: old_position.new_path,
+                new_line: old_position.new_line
+              )
+            end
+          end
+
+          context "when the text file's content has change, but the line was unchanged between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_text_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, update_line_commit) }
+
+            it "returns the new position" do
+              expect_new_position(
+                new_path: old_position.new_path,
+                new_line: old_position.new_line
+              )
+            end
+          end
+
+          context "when the text file's line was changed between the old and the new diff" do
+            let(:old_position) { position(old_path: file_name, new_path: file_name, new_line: 2, file_identifier_hash: file_identifier_hash) }
+
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_text_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, update_line_commit) }
+            let(:change_diff_refs) { diff_refs(symlink_to_text_commit, update_line_commit) }
+
+            it "returns the position of the change" do
+              expect_change_position(
+                old_path: file_name,
+                new_path: file_name,
+                old_line: 2,
+                new_line: nil
+              )
+            end
+          end
+
+          context "when the text file was removed between the old and the new diff" do
+            let(:old_diff_refs) { diff_refs(initial_commit, symlink_to_text_commit) }
+            let(:new_diff_refs) { diff_refs(initial_commit, delete_file_commit) }
+            let(:change_diff_refs) { diff_refs(symlink_to_text_commit, delete_file_commit) }
+
+            it "returns the position of the change" do
+              expect_change_position(
+                old_path: file_name,
+                new_path: file_name,
+                old_line: 3,
+                new_line: nil
+              )
+            end
+          end
+        end
+
+        describe 'from text to symlink' do
+          let(:initial_commit) { project.commit('3db7bd90bab8ce8f02c9818590b84739a2e97230') }
+          let(:text_to_symlink_commit) { project.commit('5e2c2708c2e403dece5dd25759369150aac51644') }
+          let(:branch_name) { 'diff-files-text-to-symlink' }
+          let(:file_name) { 'text-to-symlink.txt' }
+
+          context "when the position is on the added text file" do
+            let(:old_file_status) { :new }
+
+            context "when the text file gets changed to a symlink between the old and the new diff" do
+              let(:old_diff_refs) { diff_refs(initial_commit.parent, initial_commit) }
+              let(:new_diff_refs) { diff_refs(initial_commit.parent, text_to_symlink_commit) }
+              let(:change_diff_refs) { diff_refs(initial_commit, text_to_symlink_commit) }
+
+              it "returns the position of the change" do
+                expect_change_position(
+                  old_path: file_name,
+                  new_path: file_name,
+                  old_line: 3,
+                  new_line: nil
+                )
+              end
+            end
+          end
+        end
+      end
+    end
   end
 end
diff --git a/spec/lib/gitlab/diff/position_tracer_spec.rb b/spec/lib/gitlab/diff/position_tracer_spec.rb
index 47d78e0b18c..fc649812b0a 100644
--- a/spec/lib/gitlab/diff/position_tracer_spec.rb
+++ b/spec/lib/gitlab/diff/position_tracer_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::PositionTracer do
+RSpec.describe Gitlab::Diff::PositionTracer do
   include PositionTracerHelpers
 
   subject do
diff --git a/spec/lib/gitlab/diff/stats_cache_spec.rb b/spec/lib/gitlab/diff/stats_cache_spec.rb
new file mode 100644
index 00000000000..8bf510c0bdd
--- /dev/null
+++ b/spec/lib/gitlab/diff/stats_cache_spec.rb
@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Diff::StatsCache, :use_clean_rails_memory_store_caching do
+  subject(:stats_cache) { described_class.new(cachable_key: cachable_key) }
+
+  let(:key) { ['diff_stats', cachable_key, described_class::VERSION].join(":") }
+  let(:cachable_key) { 'cachecachecache' }
+  let(:stat) { Gitaly::DiffStats.new(path: 'temp', additions: 10, deletions: 15) }
+  let(:stats) { Gitlab::Git::DiffStatsCollection.new([stat]) }
+  let(:cache) { Rails.cache }
+
+  describe '#read' do
+    before do
+      stats_cache.write_if_empty(stats)
+    end
+
+    it 'returns the expected stats' do
+      expect(stats_cache.read.to_json).to eq(stats.to_json)
+    end
+  end
+
+  describe '#write_if_empty' do
+    context 'when the cache already exists' do
+      before do
+        Rails.cache.write(key, true)
+      end
+
+      it 'does not write the stats' do
+        expect(cache).not_to receive(:write)
+
+        stats_cache.write_if_empty(stats)
+      end
+    end
+
+    context 'when the cache does not exist' do
+      it 'writes the stats' do
+        expect(cache)
+          .to receive(:write)
+          .with(key, stats.as_json, expires_in: described_class::EXPIRATION)
+          .and_call_original
+
+        stats_cache.write_if_empty(stats)
+
+        expect(stats_cache.read.to_a).to eq(stats.to_a)
+      end
+
+      context 'when given non utf-8 characters' do
+        let(:non_utf8_path) { '你好'.b }
+        let(:stat) { Gitaly::DiffStats.new(path: non_utf8_path, additions: 10, deletions: 15) }
+
+        it 'writes the stats' do
+          expect(cache)
+            .to receive(:write)
+            .with(key, stats.as_json, expires_in: described_class::EXPIRATION)
+            .and_call_original
+
+          stats_cache.write_if_empty(stats)
+
+          expect(stats_cache.read.to_a).to eq(stats.to_a)
+        end
+      end
+
+      context 'when given empty stats' do
+        let(:stats) { nil }
+
+        it 'does not write the stats' do
+          expect(cache).not_to receive(:write)
+
+          stats_cache.write_if_empty(stats)
+        end
+      end
+    end
+  end
+
+  describe '#clear' do
+    it 'clears cache' do
+      expect(cache).to receive(:delete).with(key)
+
+      stats_cache.clear
+    end
+  end
+end
diff --git a/spec/lib/gitlab/diff/suggestion_diff_spec.rb b/spec/lib/gitlab/diff/suggestion_diff_spec.rb
index 0d4fe33bc47..9546c581112 100644
--- a/spec/lib/gitlab/diff/suggestion_diff_spec.rb
+++ b/spec/lib/gitlab/diff/suggestion_diff_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::SuggestionDiff do
+RSpec.describe Gitlab::Diff::SuggestionDiff do
   describe '#diff_lines' do
     let(:from_content) do
       <<-BLOB.strip_heredoc
diff --git a/spec/lib/gitlab/diff/suggestion_spec.rb b/spec/lib/gitlab/diff/suggestion_spec.rb
index d7ca0e0a522..5a5c5555818 100644
--- a/spec/lib/gitlab/diff/suggestion_spec.rb
+++ b/spec/lib/gitlab/diff/suggestion_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::Suggestion do
+RSpec.describe Gitlab::Diff::Suggestion do
   shared_examples 'correct suggestion raw content' do
     it 'returns correct raw data' do
       expect(suggestion.to_hash).to include(from_content: expected_lines.join,
diff --git a/spec/lib/gitlab/diff/suggestions_parser_spec.rb b/spec/lib/gitlab/diff/suggestions_parser_spec.rb
index 1f2af42f6e7..5efce414dc8 100644
--- a/spec/lib/gitlab/diff/suggestions_parser_spec.rb
+++ b/spec/lib/gitlab/diff/suggestions_parser_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Diff::SuggestionsParser do
+RSpec.describe Gitlab::Diff::SuggestionsParser do
   describe '.parse' do
     let(:merge_request) { create(:merge_request) }
     let(:project) { merge_request.project }