[ci] Test source_controller#update_project_config

It is called in teh old test suite from `project_controller_tests.rb#test_updating_config_file`.

src/api/spec/controllers/source_controller_spec.rb

@@ -4,6 +4,9 @@
 # CONFIG['global_write_through'] = true
 
 RSpec.describe SourceController, vcr: true do
+  let(:user) { create(:confirmed_user, login: "tom") }
+  let(:project) { user.home_project }
+
   describe "POST #global_command_orderkiwirepos" do
     it "is accessible anonymously and forwards backend errors" do
       post :global_command_orderkiwirepos, params: { cmd: "orderkiwirepos" }
@@ -29,9 +32,6 @@
   end
 
   describe "GET #show_project_meta" do
-    let(:user) { create(:confirmed_user, login: "tom") }
-    let(:project) { user.home_project }
-
     before do
       login user
       get :show_project_meta, params: { project: project }
@@ -40,4 +40,14 @@
     it { expect(response).to be_success }
     it { expect(Xmlhash.parse(response.body)["name"]).to eq(project.name) }
   end
+
+  describe "PUT #update_project_config" do
+    before do
+      login user
+      put :update_project_config, params: { project: project, comment: 'Updated by test' }
+    end
+
+    it { expect(response).to be_success }
+    it { expect(project.config.to_s).to include('Updated', 'by', 'test') }
+  end
 end