Add spec for IssuableMetadata module

spec/lib/gitlab/issuable_metadata_spec.rb

+require 'spec_helper'
+
+describe Gitlab::IssuableMetadata, lib: true do
+  let(:user)        { create(:user) }
+  let!(:project)    { create(:project, :public, :repository, creator: user, namespace: user.namespace) }
+
+  subject { Class.new { include Gitlab::IssuableMetadata }.new }
+
+  it 'returns an empty Hash if an empty collection is provided' do
+    expect(subject.issuable_meta_data(Issue.none, 'Issue')).to eq({})
+  end
+
+  context 'issues' do
+    let!(:issue) { create(:issue, author: user, project: project) }
+    let!(:closed_issue) { create(:issue, state: :closed, author: user, project: project) }
+    let!(:downvote) { create(:award_emoji, :downvote, awardable: closed_issue) }
+    let!(:upvote) { create(:award_emoji, :upvote, awardable: issue) }
+    let!(:merge_request) { create(:merge_request, :simple, author: user, assignee: user, source_project: project, target_project: project, title: "Test") }
+    let!(:closing_issues) { create(:merge_requests_closing_issues, issue: issue, merge_request: merge_request) }
+
+    it 'aggregates stats on issues' do
+      data = subject.issuable_meta_data(Issue.all, 'Issue')
+
+      expect(data.count).to eq(2)
+      expect(data[issue.id].upvotes).to eq(1)
+      expect(data[issue.id].downvotes).to eq(0)
+      expect(data[issue.id].notes_count).to eq(0)
+      expect(data[issue.id].merge_requests_count).to eq(1)
+
+      expect(data[closed_issue.id].upvotes).to eq(0)
+      expect(data[closed_issue.id].downvotes).to eq(1)
+      expect(data[closed_issue.id].notes_count).to eq(0)
+      expect(data[closed_issue.id].merge_requests_count).to eq(0)
+    end
+  end
+
+  context 'merge requests' do
+    let!(:merge_request) { create(:merge_request, :simple, author: user, assignee: user, source_project: project, target_project: project, title: "Test") }
+    let!(:merge_request_closed) { create(:merge_request, state: "closed", source_project: project, target_project: project, title: "Closed Test") }
+    let!(:downvote) { create(:award_emoji, :downvote, awardable: merge_request) }
+    let!(:upvote) { create(:award_emoji, :upvote, awardable: merge_request) }
+    let!(:note) { create(:note_on_merge_request, author: user, project: project, noteable: merge_request, note: "a comment on a MR") }
+
+    it 'aggregates stats on merge requests' do
+      data = subject.issuable_meta_data(MergeRequest.all, 'MergeRequest')
+
+      expect(data.count).to eq(2)
+      expect(data[merge_request.id].upvotes).to eq(1)
+      expect(data[merge_request.id].downvotes).to eq(1)
+      expect(data[merge_request.id].notes_count).to eq(1)
+      expect(data[merge_request.id].merge_requests_count).to eq(0)
+
+      expect(data[merge_request_closed.id].upvotes).to eq(0)
+      expect(data[merge_request_closed.id].downvotes).to eq(0)
+      expect(data[merge_request_closed.id].notes_count).to eq(0)
+      expect(data[merge_request_closed.id].merge_requests_count).to eq(0)
+    end
+  end
+end