Add pagination to dependencies API

Issue: https://gitlab.com/gitlab-org/gitlab/-/issues/335146

Changelog: security
EE: true

doc/api/dependencies.md

@@ -11,6 +11,9 @@ This API is in an alpha stage and considered unstable.
 The response payload may be subject to change or breakage
 across GitLab releases.
 
+> - Introduced in GitLab 12.1.
+> - Pagination introduced in 14.4.
+
 Every call to this endpoint requires authentication. To perform this call, user should be authorized to read repository.
 To see vulnerabilities in response, user should be authorized to read
 [Project Security Dashboard](../user/application_security/security_dashboard/index.md#project-security-dashboard).
@@ -60,3 +63,10 @@ Example response:
     }
 ]
 ```
+
+## Dependencies pagination
+
+By default, `GET` requests return 20 results at a time because the API results
+are paginated.
+
+Read more on [pagination](index.md#pagination).

ee/lib/api/dependencies.rb

@@ -2,6 +2,8 @@
 
 module API
   class Dependencies < ::API::Base
+    include PaginationParams
+
     feature_category :dependency_scanning
 
     helpers do
@@ -31,6 +33,7 @@ module API
                  coerce_with: Validations::Types::CommaSeparatedToArray.coerce,
                  desc: "Returns dependencies belonging to specified package managers: #{::Security::DependencyListService::FILTER_PACKAGE_MANAGERS_VALUES.join(', ')}.",
                  values: ::Security::DependencyListService::FILTER_PACKAGE_MANAGERS_VALUES
+        use :pagination
       end
 
       get ':id/dependencies' do
@@ -39,7 +42,7 @@ module API
         ::Gitlab::Tracking.event(self.options[:for].name, 'view_dependencies', project: user_project, user: current_user, namespace: user_project.namespace)
 
         dependency_params = declared_params(include_missing: false).merge(project: user_project)
-        dependencies = dependencies_by(dependency_params)
+        dependencies = paginate(::Gitlab::ItemsCollection.new(dependencies_by(dependency_params)))
 
         present dependencies, with: ::EE::API::Entities::Dependency, user: current_user, project: user_project
       end

ee/spec/requests/api/dependencies_spec.rb

@@ -28,11 +28,12 @@ RSpec.describe API::Dependencies do
         request
       end
 
-      it 'returns all dependencies' do
+      it 'returns paginated dependencies' do
         expect(response).to have_gitlab_http_status(:ok)
         expect(response).to match_response_schema('public_api/v4/dependencies', dir: 'ee')
+        expect(response).to include_pagination_headers
 
-        expect(json_response.length).to eq(21)
+        expect(json_response.length).to eq(20)
       end
 
       it 'returns vulnerabilities info' do
@@ -71,6 +72,17 @@ RSpec.describe API::Dependencies do
           end
         end
       end
+
+      context 'with pagination params' do
+        let(:params) { { per_page: 5, page: 5 } }
+
+        it 'returns paginated dependencies' do
+          expect(response).to match_response_schema('public_api/v4/dependencies', dir: 'ee')
+          expect(response).to include_pagination_headers
+
+          expect(json_response.length).to eq(1)
+        end
+      end
     end
 
     context 'without permissions to see vulnerabilities' do