Added more complicated columns to Issues CSV

Milestone and Labels columns needed ruby code to build instead of using `pluck` directly on the relation.
Instead it now calls a lambda for every value in a row.
This approach can be less efficient especially if data isn’t eager loaded.

app/views/projects/issues/index.csv.ruby

@@ -3,17 +3,28 @@ columns = {
   'Title' => 'title',
   'State' => 'state',
   'Description' => 'description',
-  'Author Id' => 'author_id',
-  'Assignee Id' => 'assignee_id',
+  'Author' => 'author_name',
+  'Assignee' => 'assignee_name',
+  'Confidential' => 'confidential',
   'Due Date' => 'due_date',
   'Created At' => 'created_at',
-  'Updated At' => 'updated_at'
+  'Updated At' => 'updated_at',
+  'Milestone' => -> (issue) { issue.milestone&.title },
+  'Labels' => -> (issue) { issue.label_names.join(',').presence },
 }
 
 CSV.generate do |csv|
   csv << columns.keys
 
-  @issues.pluck(*columns.values).each do |row|
+  @issues.each do |issue|
+    row = columns.values.map do |attribute|
+      if attribute.respond_to?(:call)
+        attribute.call(issue)
+      else
+        issue.send(attribute)
+      end
+    end
+
     csv << row
   end
 end

spec/features/issues/csv_spec.rb

@@ -5,10 +5,7 @@ describe 'Issues csv', feature: true do
   let(:project) { create(:project, :public) }
   let!(:issue)  { create(:issue, project: project) }
 
-  before do
-    login_as(user)
-    visit namespace_project_issues_path(project.namespace, project, format: :csv)
-  end
+  before { login_as(user) }
 
   it "downloads from a project's issue index" do
     visit namespace_project_issues_path(project.namespace, project)
@@ -16,11 +13,49 @@ describe 'Issues csv', feature: true do
     expect(page.response_headers['Content-Type']).to include('csv')
   end
 
-  it 'includes title' do
+  context 'includes' do
+    let(:label1)    { create(:label, project: project, title: 'Feature') }
+    let(:label2)    { create(:label, project: project, title: 'labels') }
+    let(:milestone) { create(:milestone, title: "v1.0", project: project) }
+
+    before do
+      issue.update!(milestone: milestone, assignee: user, description: 'Issue with details', labels: [label1, label2])
+      visit namespace_project_issues_path(project.namespace, project, format: :csv)
+    end
+
+    specify 'title' do
       expect(csv[0]['Title']).to eq issue.title
     end
 
-  it 'includes description' do
+    specify 'description' do
       expect(csv[0]['Description']).to eq issue.description
     end
+
+    specify 'author name' do
+      expect(csv[0]['Author']).to eq issue.author_name
+    end
+
+    specify 'assignee name' do
+      expect(csv[0]['Assignee']).to eq issue.assignee_name
+    end
+
+    specify 'confidential' do
+      expect(csv[0]['Confidential']).to eq 'false'
+    end
+
+    specify 'milestone' do
+      expect(csv[0]['Milestone']).to eq issue.milestone.title
+    end
+
+    specify 'labels' do
+      expect(csv[0]['Labels']).to eq 'Feature,labels'
+    end
+  end
+
+  context 'with minimal details' do
+    it 'renders labels as nil' do
+      visit namespace_project_issues_path(project.namespace, project, format: :csv)
+      expect(csv[0]['Labels']).to eq nil
+    end
+  end
 end