Add feature test for Rubygems uploads

This tests Workhorse uploads for both integer project IDs and encoded
forms.

spec/features/file_uploads/rubygem_package_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Upload a RubyGems package', :api, :js do
+  include_context 'file upload requests helpers'
+
+  let_it_be(:project) { create(:project) }
+  let_it_be(:user) { create(:user) }
+  let_it_be(:personal_access_token) { create(:personal_access_token, user: user) }
+
+  let(:api_path) { "/projects/#{project_id}/packages/rubygems/api/v1/gems" }
+  let(:url) { capybara_url(api(api_path)) }
+  let(:file) { fixture_file_upload('spec/fixtures/dk.png') }
+
+  subject do
+    HTTParty.post(
+      url,
+      headers: { 'Authorization' => personal_access_token.token },
+      body: { file: file }
+    )
+  end
+
+  before do
+    project.add_maintainer(user)
+  end
+
+  RSpec.shared_examples 'for a Rubygems package' do
+    it 'creates package files' do
+      expect { subject }
+        .to change { Packages::Package.rubygems.count }.by(1)
+        .and change { Packages::PackageFile.count }.by(1)
+    end
+
+    it { expect(subject.code).to eq(201) }
+  end
+
+  context 'with an integer project ID' do
+    let(:project_id) { project.id }
+
+    it_behaves_like 'handling file uploads', 'for a Rubygems package'
+  end
+
+  context 'with an encoded project ID' do
+    let(:project_id) { "#{project.namespace.path}%2F#{project.path}" }
+
+    it_behaves_like 'handling file uploads', 'for a Rubygems package'
+  end
+end