Add api for packages index

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

ee/changelogs/unreleased/8681-api-endpoint-for-package-repositories.yml

+---
+title: Add API endpoint for project packages
+merge_request: 9259
+author:
+type: added

ee/lib/api/packages.rb

+# frozen_string_literal: true
+
+module API
+  class Packages < Grape::API
+    include PaginationParams
+
+    before do
+      require_packages_enabled!
+      authorize_packages_feature!
+      authorize_download_package!
+    end
+
+    helpers ::API::Helpers::PackagesHelpers
+
+    params do
+      requires :id, type: String, desc: 'The ID of a project'
+    end
+    resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      desc 'Get all project packages' do
+        success EE::API::Entities::Package
+      end
+      params do
+        use :pagination
+      end
+      get ':id/packages' do
+        packages = user_project.packages
+
+        present paginate(packages), with: EE::API::Entities::Package
+      end
+    end
+  end
+end

ee/lib/ee/api/endpoints.rb

@@ -22,6 +22,7 @@ module EE
         mount ::API::ProjectPushRule
         mount ::API::MavenPackages
         mount ::API::NpmPackages
+        mount ::API::Packages
       end
     end
   end

ee/lib/ee/api/entities.rb

@@ -499,6 +499,13 @@ module EE
         expose :name
         expose :versions
       end
+
+      class Package < Grape::Entity
+        expose :id
+        expose :name
+        expose :version
+        expose :package_type
+      end
     end
   end
 end

ee/spec/fixtures/api/schemas/public_api/v4/packages/packages.json

+{
+  "type": "array",
+  "items": {
+    "type": "object",
+    "required" : ["name", "version", "packages_type"],
+    "properties" : {
+      "name": { "type": "string" },
+      "version": { "type": "string" },
+      "packages_type": { "type": "string" }
+    }
+  }
+}

ee/spec/requests/api/packages_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe API::Packages do
+  let(:user) { create(:user) }
+  let(:project) { create(:project, :public) }
+  let(:package) { create(:npm_package, project: project) }
+  let(:params) { nil }
+
+  before do
+    project.add_developer(user)
+    stub_licensed_features(packages: true)
+  end
+
+  describe 'GET /projects/:id/packages' do
+    let(:url) { "/projects/#{project.id}/packages" }
+
+    context 'when packages feature is disabled' do
+      before do
+        stub_licensed_features(packages: false)
+      end
+
+      it 'returns 403' do
+        get api(url, user)
+
+        expect(response).to have_gitlab_http_status(403)
+      end
+    end
+
+    context 'when packages feature is enabled' do
+      context 'project is public' do
+        it 'returns 200' do
+          get api(url)
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+      end
+
+      context 'project is private' do
+        before do
+          project.update(visibility_level: Gitlab::VisibilityLevel::PRIVATE)
+        end
+
+        it 'returns 404 for non authenticated user' do
+          get api(url)
+
+          expect(response).to have_gitlab_http_status(404)
+        end
+
+        it 'returns 404 for a user without access to the project' do
+          project.team.truncate
+
+          get api(url, user)
+
+          expect(response).to have_gitlab_http_status(404)
+        end
+
+        it 'returns 200 and valid response schema' do
+          get api(url, user)
+
+          expect(response).to have_gitlab_http_status(200)
+          expect(response).to match_response_schema('public_api/v4/packages/packages', dir: 'ee')
+        end
+      end
+    end
+
+    context 'with pagination params' do
+      let(:per_page) { 2 }
+      let!(:package1) { create(:npm_package, project: project) }
+      let!(:package2) { create(:npm_package, project: project) }
+      let!(:package3) { create(:maven_package, project: project) }
+
+      before do
+        stub_licensed_features(packages: true)
+      end
+
+      context 'when viewing the first page' do
+        let(:expected) { [package1.id, package2.id] }
+
+        it 'returns first 2 packages' do
+          get api(url, user), params: { page: 1, per_page: per_page }
+
+          expect_paginated_array_response(expected)
+        end
+      end
+
+      context 'viewing the second page' do
+        let(:expected) { [package3.id] }
+
+        it 'returns the last package' do
+          get api(url, user), params: { page: 2, per_page: per_page }
+
+          expect_paginated_array_response(expected)
+        end
+      end
+    end
+  end
+end