Feature: delegate all open discussions to Issue

When a merge request can only be merged when all discussions are
resolved. This feature allows to easily delegate those discussions to a
new issue, while marking them as resolved in the merge request.

The user is presented with a new issue, prepared with mentions of all
unresolved discussions, including the first unresolved note of the
discussion, time and link to the note.

When the issue is created, the discussions in the merge request will get
a system note directing the user to the newly created issue.

2 files changed, 173 insertions, 0 deletions

diff --git a/spec/services/issues/build_service_spec.rb b/spec/services/issues/build_service_spec.rb
new file mode 100644
index 00000000000..4cfba35c830
--- /dev/null
+++ b/spec/services/issues/build_service_spec.rb
@@ -0,0 +1,130 @@
+require 'spec_helper.rb'
+
+describe Issues::BuildService, services: true do
+  let(:project) { create(:project) }
+  let(:user) { create(:user) }
+
+  before do
+    project.team << [user, :developer]
+  end
+
+  context 'for discussions in a merge request' do
+    let(:merge_request) { create(:merge_request_with_diff_notes, source_project: project) }
+    let(:issue) { described_class.new(project, user, merge_request_for_resolving_discussions: merge_request).execute }
+
+    def position_on_line(line_number)
+      Gitlab::Diff::Position.new(
+        old_path: "files/ruby/popen.rb",
+        new_path: "files/ruby/popen.rb",
+        old_line: nil,
+        new_line: line_number,
+        diff_refs: merge_request.diff_refs
+      )
+    end
+
+    describe '#items_for_discussions' do
+      it 'has an item for each discussion' do
+        create(:diff_note_on_merge_request, noteable: merge_request, project: merge_request.source_project, position: position_on_line(13))
+        service = described_class.new(project, user, merge_request_for_resolving_discussions: merge_request)
+
+        service.execute
+
+        expect(service.items_for_discussions.size).to eq(2)
+      end
+    end
+
+    describe '#item_for_discussion' do
+      let(:service) { described_class.new(project, user, merge_request_for_resolving_discussions: merge_request) }
+
+      it 'mentions the author of the note' do
+        discussion = Discussion.new([create(:diff_note_on_merge_request, author: create(:user, username: 'author'))])
+        expect(service.item_for_discussion(discussion)).to include('@author')
+      end
+
+      it 'wraps the note in a blockquote' do
+        note_text = "This is a string\n"\
+                    ">>>\n"\
+                    "with a blockquote\n"\
+                    "> That has a quote\n"\
+                    ">>>\n"
+        note_result = "This is a string\n"\
+                    "> with a blockquote\n"\
+                    "> > That has a quote\n"
+        discussion = Discussion.new([create(:diff_note_on_merge_request, note: note_text)])
+        expect(service.item_for_discussion(discussion)).to include(">>>\n#{note_result}\n>>>")
+      end
+    end
+
+    describe '#execute' do
+      it 'has the merge request reference in the title' do
+        expect(issue.title).to include(merge_request.title)
+      end
+
+      it 'has the reference of the merge request in the description' do
+        expect(issue.description).to include(merge_request.to_reference)
+      end
+
+      it 'does not assign title when a title was given' do
+        issue = described_class.new(project, user,
+                                    merge_request_for_resolving_discussions: merge_request,
+                                    title: 'What an issue').execute
+
+        expect(issue.title).to eq('What an issue')
+      end
+
+      it 'does not assign description when a description was given' do
+        issue = described_class.new(project, user,
+                                    merge_request_for_resolving_discussions: merge_request,
+                                    description: 'Fix at your earliest conveignance').execute
+
+        expect(issue.description).to eq('Fix at your earliest conveignance')
+      end
+
+      describe 'with multiple discussions' do
+        before do
+          create(:diff_note_on_merge_request, noteable: merge_request, project: merge_request.target_project, position: position_on_line(15))
+        end
+
+        it 'mentions all the authors in the description' do
+          authors = merge_request.diff_discussions.map(&:author)
+
+          expect(issue.description).to include(*authors.map(&:to_reference))
+        end
+
+        it 'has a link for each unresolved discussion in the description' do
+          notes = merge_request.diff_discussions.map(&:first_note)
+          links = notes.map { |note| Gitlab::UrlBuilder.build(note) }
+
+          expect(issue.description).to include(*links)
+        end
+
+        it 'mentions additional notes' do
+          create_list(:diff_note_on_merge_request, 2, noteable: merge_request, project: merge_request.target_project, position: position_on_line(15))
+
+          expect(issue.description).to include('(+2 comments)')
+        end
+      end
+    end
+  end
+
+  context 'For a merge request without discussions' do
+    let(:merge_request) { create(:merge_request, source_project: project) }
+
+    describe '#execute' do
+      it 'mentions the merge request in the description' do
+        issue = described_class.new(project, user, merge_request_for_resolving_discussions: merge_request).execute
+
+        expect(issue.description).to include("Review the conversation in #{merge_request.to_reference}")
+      end
+    end
+  end
+
+  describe '#execute' do
+    it 'builds a new issues with given params' do
+      issue = described_class.new(project, user, title: 'Issue #1', description: 'Issue description').execute
+
+      expect(issue.title).to eq('Issue #1')
+      expect(issue.description).to eq('Issue description')
+    end
+  end
+end
diff --git a/spec/services/issues/create_service_spec.rb b/spec/services/issues/create_service_spec.rb
index 5c0331ebe66..8bde61ee336 100644
--- a/spec/services/issues/create_service_spec.rb
+++ b/spec/services/issues/create_service_spec.rb
@@ -136,5 +136,48 @@ describe Issues::CreateService, services: true do
     end
 
     it_behaves_like 'new issuable record that supports slash commands'
+
+    context 'for a merge request' do
+      let(:discussion) { Discussion.for_diff_notes([create(:diff_note_on_merge_request)]).first }
+      let(:merge_request) { discussion.noteable }
+      let(:project) { merge_request.source_project }
+      let(:opts) { { merge_request_for_resolving_discussions: merge_request } }
+
+      before do
+        project.team << [user, :master]
+      end
+
+      it 'resolves the discussion for the merge request' do
+        described_class.new(project, user, opts).execute
+        discussion.first_note.reload
+
+        expect(discussion.resolved?).to be(true)
+      end
+
+      it 'added a system note to the discussion' do
+        described_class.new(project, user, opts).execute
+
+        reloaded_discussion = MergeRequest.find(merge_request.id).discussions.first
+
+        expect(reloaded_discussion.last_note.system).to eq(true)
+      end
+
+      it 'assigns the title and description for the issue' do
+        issue = described_class.new(project, user, opts).execute
+
+        expect(issue.title).not_to be_nil
+        expect(issue.description).not_to be_nil
+      end
+
+      it 'can set nil explicityly to the title and description' do
+        issue = described_class.new(project, user,
+                                    merge_request_for_resolving_discussions: merge_request,
+                                    description: nil,
+                                    title: nil).execute
+
+        expect(issue.description).to be_nil
+        expect(issue.title).to be_nil
+      end
+    end
   end
 end