Allow hidden pacakge files to be downloaded

Modify installable status.
Enable gitlab api to return the hidden package files.

Changelog: changed

app/models/packages/package.rb

@@ -7,7 +7,7 @@ class Packages::Package < ApplicationRecord
   include Gitlab::Utils::StrongMemoize
 
   DISPLAYABLE_STATUSES = [:default, :error].freeze
-  INSTALLABLE_STATUSES = [:default].freeze
+  INSTALLABLE_STATUSES = [:default, :hidden].freeze
 
   enum package_type: {
     maven: 1,

spec/finders/packages/go/package_finder_spec.rb

@@ -59,7 +59,7 @@ RSpec.describe Packages::Go::PackageFinder do
       let(:version_name) { version.name }
 
       before do
-        package.update_column(:status, 1)
+        package.update_column(:status, :error)
       end
 
       it { is_expected.to eq(nil) }

spec/finders/packages/maven/package_finder_spec.rb

@@ -39,7 +39,7 @@ RSpec.describe ::Packages::Maven::PackageFinder do
         let(:param_path) { package.maven_metadatum.path }
 
         before do
-          package.update_column(:status, 1)
+          package.update_column(:status, :error)
         end
 
         it { expect { subject }.to raise_error(ActiveRecord::RecordNotFound) }

spec/finders/packages/npm/package_finder_spec.rb

@@ -52,7 +52,7 @@ RSpec.describe ::Packages::Npm::PackageFinder do
 
       context 'with an uninstallable package' do
         before do
-          package.update_column(:status, 1)
+          package.update_column(:status, :error)
         end
 
         it { is_expected.to be_empty }

spec/finders/packages/nuget/package_finder_spec.rb

@@ -36,7 +36,7 @@ RSpec.describe Packages::Nuget::PackageFinder do
 
       context 'with an uninstallable package' do
         before do
-          package1.update_column(:status, 1)
+          package1.update_column(:status, :error)
         end
 
         it { is_expected.to contain_exactly(package2) }

spec/models/packages/package_spec.rb

@@ -839,6 +839,7 @@ RSpec.describe Packages::Package, type: :model do
     end
 
     context 'status scopes' do
+      let_it_be(:default_package) { create(:maven_package, :default) }
       let_it_be(:hidden_package) { create(:maven_package, :hidden) }
       let_it_be(:processing_package) { create(:maven_package, :processing) }
       let_it_be(:error_package) { create(:maven_package, :error) }
@@ -856,11 +857,15 @@ RSpec.describe Packages::Package, type: :model do
       describe '.installable' do
         subject { described_class.installable }
 
-        it 'does not include non-displayable packages', :aggregate_failures do
+        it 'does not include non-installable packages', :aggregate_failures do
           is_expected.not_to include(error_package)
-          is_expected.not_to include(hidden_package)
           is_expected.not_to include(processing_package)
         end
+
+        it 'includes installable packages', :aggregate_failures do
+          is_expected.to include(default_package)
+          is_expected.to include(hidden_package)
+        end
       end
 
       describe '.with_status' do

spec/requests/api/generic_packages_spec.rb

@@ -574,6 +574,27 @@ RSpec.describe API::GenericPackages do
       end
     end
 
+    context 'with package status' do
+      where(:package_status, :expected_status) do
+        :default      | :success
+        :hidden       | :success
+        :error        | :not_found
+      end
+
+      with_them do
+        before do
+          project.add_developer(user)
+          package.update!(status: package_status)
+        end
+
+        it "responds with #{params[:expected_status]}" do
+          download_file(personal_access_token_header)
+
+          expect(response).to have_gitlab_http_status(expected_status)
+        end
+      end
+    end
+
     context 'event tracking' do
       let(:snowplow_gitlab_standard_context) { { project: project, namespace: project.namespace, user: user } }