Rails5: fix artifacts controller download spec

Rails5 has params[:file_type] as '' if file_type is included as nil
in the request

changelogs/unreleased/rails5-fix-artifacts-controller-spec.yml

+---
+title: 'Rails5: fix artifacts controller download spec Rails5 has params[:file_type]
+  as '''' if file_type is included as nil in the request'
+merge_request: 22123
+author: Jasper Maes
+type: other

spec/controllers/projects/artifacts_controller_spec.rb

@@ -19,15 +19,17 @@ describe Projects::ArtifactsController do
   end
 
   describe 'GET download' do
-    subject { get :download, namespace_id: project.namespace, project_id: project, job_id: job, file_type: file_type }
+    def download_artifact(extra_params = {})
+      params = { namespace_id: project.namespace, project_id: project, job_id: job }.merge(extra_params)
 
-    context 'when no file type is supplied' do
-      let(:file_type) { nil }
+      get :download, params
+    end
 
+    context 'when no file type is supplied' do
       it 'sends the artifacts file' do
         expect(controller).to receive(:send_file).with(job.artifacts_file.path, hash_including(disposition: 'attachment')).and_call_original
 
-        subject
+        download_artifact
       end
     end
 
@@ -36,7 +38,7 @@ describe Projects::ArtifactsController do
         let(:file_type) { 'invalid' }
 
         it 'returns 404' do
-          subject
+          download_artifact(file_type: file_type)
 
           expect(response).to have_gitlab_http_status(404)
         end
@@ -52,7 +54,7 @@ describe Projects::ArtifactsController do
         it 'sends the codequality report' do
           expect(controller).to receive(:send_file).with(job.job_artifacts_codequality.file.path, hash_including(disposition: 'attachment')).and_call_original
 
-          subject
+          download_artifact(file_type: file_type)
         end
       end
     end