Move diff_line preparation into presenter

Update spec

app/controllers/projects/blob_controller.rb

@@ -91,51 +91,20 @@ class Projects::BlobController < Projects::ApplicationController
     apply_diff_view_cookie!
     @form = Blobs::UnfoldPresenter.new(blob, params.to_unsafe_h)
-    @lines = @form.lines
-    @match_line = @form.match_line_text
-    # We can keep only 'render_diff_lines' from this conditional when
+    # keep only json rendering when
     # https://gitlab.com/gitlab-org/gitlab-ce/issues/44988 is done
     if rendered_for_merge_request?
-      render_diff_lines
+      render json: DiffLineSerializer.new.represent(@form.diff_lines)
     else
+      @lines = @form.lines
+      @match_line = @form.match_line_text
       render layout: false
     end
   end
   private
-  # Converts a String array to Gitlab::Diff::Line array
-  def render_diff_lines
-    @lines.map! do |line|
-      diff_line = Gitlab::Diff::Line.new(line, nil, nil, nil, nil)
-      diff_line.rich_text = line
-      diff_line
-    end
-
-    add_match_line
-
-    render json: DiffLineSerializer.new.represent(@lines)
-  end
-
-  def add_match_line
-    return unless @form.unfold?
-
-    if @form.bottom? && @form.to < @blob.lines.size
-      old_pos = @form.to - @form.offset
-      new_pos = @form.to
-    elsif @form.since != 1
-      old_pos = new_pos = @form.since
-    end
-
-    # Match line is not needed when it reaches the top limit or bottom limit of the file.
-    return unless new_pos
-
-    @match_line = Gitlab::Diff::Line.new(@match_line, 'match', nil, old_pos, new_pos)
-
-    @form.bottom? ? @lines.push(@match_line) : @lines.unshift(@match_line)
-  end
-
   def blob
     @blob ||= @repository.blob_at(@commit.id, @path)

app/presenters/blobs/unfold_presenter.rb

@@ -25,6 +25,17 @@ module Blobs
       end
     end
+    # Converts a String array to Gitlab::Diff::Line array, with match line added
+    def diff_lines
+      diff_lines = lines.map do |line|
+        Gitlab::Diff::Line.new(line, nil, nil, nil, nil, rich_text: line)
+      end
+
+      add_match_line(diff_lines)
+
+      diff_lines
+    end
+
     def lines
       strong_memoize(:lines) do
         lines = @all_lines
@@ -40,5 +51,25 @@ module Blobs
       line = [since, lines_length].join(',')
       "@@ -#{line}+#{line} @@"
     end
+
+    private
+
+    def add_match_line(diff_lines)
+      return unless unfold?
+
+      if bottom? && to < @all_lines.size
+        old_pos = to - offset
+        new_pos = to
+      elsif since != 1
+        old_pos = new_pos = since
+      end
+
+      # Match line is not needed when it reaches the top limit or bottom limit of the file.
+      return unless new_pos
+
+      match_line = Gitlab::Diff::Line.new(match_line_text, 'match', nil, old_pos, new_pos)
+
+      bottom? ? diff_lines.push(match_line) : diff_lines.unshift(match_line)
+    end
   end
 end

spec/controllers/projects/blob_controller_spec.rb

@@ -144,66 +144,34 @@ describe Projects::BlobController do
       end
       context 'when rendering for merge request' do
-        it 'renders diff context lines Gitlab::Diff::Line array' do
-          do_get(since: 1, to: 5, offset: 10, from_merge_request: true)
-
-          lines = JSON.parse(response.body)
-
-          expect(lines.first).to have_key('type')
-          expect(lines.first).to have_key('rich_text')
-          expect(lines.first).to have_key('rich_text')
+        let(:presenter) { double(:presenter, diff_lines: diff_lines) }
+        let(:diff_lines) do
+          Array.new(3, Gitlab::Diff::Line.new('plain', nil, nil, nil, nil, rich_text: 'rich'))
         end
-        context 'when rendering match lines' do
-          it 'adds top match line when "since" is less than 1' do
-            do_get(since: 5, to: 10, offset: 10, from_merge_request: true)
-
-            match_line = JSON.parse(response.body).first
-
-            expect(match_line['type']).to eq('match')
-            expect(match_line['meta_data']).to have_key('old_pos')
-            expect(match_line['meta_data']).to have_key('new_pos')
-          end
-
-          it 'does not add top match line when "since" is equal 1' do
-            do_get(since: 1, to: 10, offset: 10, from_merge_request: true)
-
-            match_line = JSON.parse(response.body).first
-
-            expect(match_line['type']).to be_nil
-          end
-
-          it 'adds bottom match line when "to" is less than blob size' do
-            do_get(since: 1, to: 5, offset: 10, from_merge_request: true, bottom: true)
-
-            match_line = JSON.parse(response.body).last
-
-            expect(match_line['type']).to eq('match')
-            expect(match_line['meta_data']).to have_key('old_pos')
-            expect(match_line['meta_data']).to have_key('new_pos')
-          end
-          it 'does not add bottom match line when "to" is equal to blob size' do
-            commit_id = project.repository.commit('master').id
-            blob = project.repository.blob_at(commit_id, 'CHANGELOG')
-            do_get(since: 1, to: blob.lines.count, offset: 10, from_merge_request: true, bottom: true)
-            match_line = JSON.parse(response.body).last
-            expect(match_line['type']).to be_nil
+        before do
+          allow(Blobs::UnfoldPresenter).to receive(:new).and_return(presenter)
+        end
+        it 'renders diff context lines Gitlab::Diff::Line array' do
+          do_get(since: 1, to: 2, offset: 0, from_merge_request: true)
+          lines = JSON.parse(response.body)
+          expect(lines.size).to eq(diff_lines.size)
+          lines.each do |line|
+            expect(line).to have_key('type')
+            expect(line['text']).to eq('plain')
+            expect(line['rich_text']).to eq('rich')
           end
-          it 'returns all lines if "full" is true' do
-            commit_id = project.repository.commit('master').id
-            blob = project.repository.blob_at(commit_id, 'CHANGELOG')
-            do_get(full: true, from_merge_request: true, bottom: true)
-            match_lines = JSON.parse(response.body)
-            expect(match_lines.size).to eq(blob.lines.count - 1)
-            expect(match_lines.last['type']).to be_nil
-            expect(match_lines.last['text']).to include(blob.lines.last)
-          end
+        end
+        it 'handles full being true' do
+          do_get(full: true, from_merge_request: true)
+          lines = JSON.parse(response.body)
+          expect(lines.size).to eq(diff_lines.size)
         end
       end
     end

spec/presenters/blobs/unfold_presenter_spec.rb

@@ -41,6 +41,81 @@ describe Blobs::UnfoldPresenter do
     end
   end
+  describe '#diff_lines' do
+    let(:total_lines) { 50 }
+    let(:blob) { fake_blob(path: 'foo', data: (1..total_lines).to_a.join("\n")) }
+
+    context 'when "full" is true' do
+      let(:params) { { full: true } }
+
+      it 'returns all lines' do
+        lines = subject.diff_lines
+
+        expect(lines.size).to eq(total_lines)
+
+        lines.each.with_index do |line, index|
+          expect(line.text).to include("LC#{index + 1}")
+          expect(line.text).to eq(line.rich_text)
+          expect(line.type).to be_nil
+        end
+      end
+
+      context 'when last line is empty' do
+        let(:blob) { fake_blob(path: 'foo', data: "1\n2\n") }
+
+        it 'disregards last line' do
+          lines = subject.diff_lines
+
+          expect(lines.size).to eq(2)
+        end
+      end
+    end
+
+    context 'when "since" is equal to 1' do
+      let(:params) { { since: 1, to: 10, offset: 10 } }
+
+      it 'does not add top match line' do
+        line = subject.diff_lines.first
+
+        expect(line.type).to be_nil
+      end
+    end
+
+    context 'when since is greater than 1' do
+      let(:params) { { since: 5, to: 10, offset: 10 } }
+
+      it 'adds top match line' do
+        line = subject.diff_lines.first
+
+        expect(line.type).to eq('match')
+        expect(line.old_pos).to eq(5)
+        expect(line.new_pos).to eq(5)
+      end
+    end
+
+    context 'when "to" is less than blob size' do
+      let(:params) { { since: 1, to: 5, offset: 10, bottom: true } }
+
+      it 'adds bottom match line' do
+        line = subject.diff_lines.last
+
+        expect(line.type).to eq('match')
+        expect(line.old_pos).to eq(-5)
+        expect(line.new_pos).to eq(5)
+      end
+    end
+
+    context 'when "to" is equal to blob size' do
+      let(:params) { { since: 1, to: total_lines, offset: 10, bottom: true } }
+
+      it 'does not add bottom match line' do
+        line = subject.diff_lines.last
+
+        expect(line.type).to be_nil
+      end
+    end
+  end
+
   describe '#lines' do
     context 'when scope is specified' do
       let(:params) { { since: 2, to: 3 } }