Add package files API endpoint

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

doc/api/packages.md

@@ -41,3 +41,58 @@ Example response:
 ```
 
 By default, the `GET` request will return 20 results, since the API is [paginated](README.md#pagination).
+
+## List package files
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9305) in GitLab 11.8.
+
+Get a list of package files of a single package. 
+
+```
+GET /projects/:id/packages/:package_id/package_files
+```
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `id`      | integer/string | yes | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user. |
+| `package_id`      | integer | yes | The ID of a package. |
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/1/packages/4/package_files
+```
+
+Example response:
+
+```json
+[
+  {
+    "id": 25,
+    "package_id": 4,
+    "created_at": "2018-11-07T15:25:52.199Z",
+    "file_name": "my-app-1.5-20181107.152550-1.jar",
+    "size": 2421,
+    "file_md5": "58e6a45a629910c6ff99145a688971ac",
+    "file_sha1": "ebd193463d3915d7e22219f52740056dfd26cbfe"
+  },
+  {
+    "id": 26,
+    "package_id": 4,
+    "created_at": "2018-11-07T15:25:56.776Z",
+    "file_name": "my-app-1.5-20181107.152550-1.pom",
+    "size": 1122,
+    "file_md5": "d90f11d851e17c5513586b4a7e98f1b2",
+    "file_sha1": "9608d068fe88aff85781811a42f32d97feb440b5"
+  },
+  {
+    "id": 27,
+    "package_id": 4,
+    "created_at": "2018-11-07T15:26:00.556Z",
+    "file_name": "maven-metadata.xml",
+    "size": 767,
+    "file_md5": "6dfd0cce1203145a927fef5e3a1c650c",
+    "file_sha1": "d25932de56052d320a8ac156f745ece73f6a8cd2"
+  }
+]
+```
+
+By default, the `GET` request will return 20 results, since the API is [paginated](README.md#pagination).

ee/app/finders/packages/package_finder.rb

+# frozen_string_literal: true
+module Packages
+  class PackageFinder
+    def initialize(project, package_id)
+      @project = project
+      @package_id = package_id
+    end
+
+    def execute
+      @project.packages.find(@package_id)
+    end
+  end
+end

ee/changelogs/unreleased/dz-package-files-api.yml

+---
+title: Add package files API endpoint
+merge_request: 9305
+author:
+type: added

ee/lib/api/package_files.rb

+# frozen_string_literal: true
+
+module API
+  class PackageFiles < Grape::API
+    include PaginationParams
+
+    before do
+      require_packages_enabled!
+      authorize_packages_feature!
+      authorize_read_package!
+    end
+
+    helpers ::API::Helpers::PackagesHelpers
+
+    params do
+      requires :id, type: String, desc: 'The ID of a project'
+      requires :package_id, type: Integer, desc: 'The ID of a package'
+    end
+    resource :projects, requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
+      desc 'Get all package files' do
+        detail 'This feature was introduced in GitLab 11.8'
+        success EE::API::Entities::PackageFile
+      end
+      params do
+        use :pagination
+      end
+      get ':id/packages/:package_id/package_files' do
+        package = ::Packages::PackageFinder
+          .new(user_project, params[:package_id]).execute
+
+        present paginate(package.package_files), with: EE::API::Entities::PackageFile
+      end
+    end
+  end
+end

ee/lib/ee/api/endpoints.rb

@@ -23,6 +23,7 @@ module EE
         mount ::API::MavenPackages
         mount ::API::NpmPackages
         mount ::API::Packages
+        mount ::API::PackageFiles
       end
     end
   end

ee/lib/ee/api/entities.rb

@@ -507,6 +507,12 @@ module EE
         expose :version
         expose :package_type
       end
+
+      class PackageFile < Grape::Entity
+        expose :id, :package_id, :created_at
+        expose :file_name, :size
+        expose :file_md5, :file_sha1
+      end
     end
   end
 end

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

+{
+  "type": "array",
+  "items": {
+    "type": "object",
+    "required" : ["id", "package_id", "file_name"],
+    "properties" : {
+      "id": { "type": "integer" },
+      "package_id": { "type": "integer" },
+      "file_name": { "type": "string" },
+      "file_sha1": { "type": "string" }
+    }
+  }
+}

ee/spec/requests/api/package_files_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe API::PackageFiles do
+  let(:user) { create(:user) }
+  let(:project) { create(:project, :public) }
+  let(:package) { create(:maven_package, project: project) }
+
+  before do
+    project.add_developer(user)
+  end
+
+  describe 'GET /projects/:id/packages/:package_id/package_files' do
+    let(:url) { "/projects/#{project.id}/packages/#{package.id}/package_files" }
+
+    context 'packages feature enabled' do
+      before do
+        stub_licensed_features(packages: true)
+      end
+
+      context 'project is public' do
+        it 'returns 200' do
+          get api(url)
+
+          expect(response).to have_gitlab_http_status(200)
+        end
+
+        it 'returns 404 if package does not exist' do
+          get api("/projects/#{project.id}/packages/0/package_files")
+
+          expect(response).to have_gitlab_http_status(404)
+        end
+      end
+
+      context 'project is private' do
+        let(:project) { create(:project, :private) }
+
+        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/package_files', dir: 'ee')
+        end
+      end
+
+      context 'with pagination params' do
+        let(:per_page) { 2 }
+        let!(:package_file_1) { package.package_files[0] }
+        let!(:package_file_2) { package.package_files[1] }
+        let!(:package_file_3) { package.package_files[2] }
+
+        before do
+          stub_licensed_features(packages: true)
+        end
+
+        context 'when viewing the first page' do
+          it 'returns first 2 packages' do
+            get api(url, user), params: { page: 1, per_page: per_page }
+
+            expect_paginated_array_response([package_file_1.id, package_file_2.id])
+          end
+        end
+
+        context 'viewing the second page' do
+          it 'returns the last package' do
+            get api(url, user), params: { page: 2, per_page: per_page }
+
+            expect_paginated_array_response([package_file_3.id])
+          end
+        end
+      end
+    end
+
+    context 'packages feature 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
+  end
+end