Fix and improve stubbed test for WIP commit ref

spec/services/merge_requests/refresh_service_spec.rb

@@ -400,37 +400,21 @@ describe MergeRequests::RefreshService do
       end
 
       it 'references the commit that caused the Work in Progress status' do
-        refresh_service.execute(@oldrev, @newrev, 'refs/heads/master')
-        allow(refresh_service).to receive(:find_new_commits)
-        refresh_service.instance_variable_set("@commits", [
-          double(
-            id: 'aaaaaaa',
-            sha: '38008cb17ce1466d8fec2dfa6f6ab8dcfe5cf49e',
-            short_id: 'aaaaaaa',
-            title: 'Fix issue',
-            work_in_progress?: false
-          ),
-          double(
-            id: 'bbbbbbb',
-            sha: '498214de67004b1da3d820901307bed2a68a8ef6',
-            short_id: 'bbbbbbb',
-            title: 'fixup! Fix issue',
-            work_in_progress?: true,
-            to_reference: 'bbbbbbb'
-          ),
-          double(
-            id: 'ccccccc',
-            sha: '1b12f15a11fc6e62177bef08f47bc7b5ce50b141',
-            short_id: 'ccccccc',
-            title: 'fixup! Fix issue',
-            work_in_progress?: true,
-            to_reference: 'ccccccc'
-          )
-        ])
-        refresh_service.execute(@oldrev, @newrev, 'refs/heads/wip')
-        reload_mrs
-        expect(@merge_request.notes.last.note).to eq(
-          "marked as a **Work In Progress** from bbbbbbb"
+        wip_merge_request = create(:merge_request,
+                                   source_project: @project,
+                                   source_branch: 'wip',
+                                   target_branch: 'master',
+                                   target_project: @project)
+
+        commits = wip_merge_request.commits
+        oldrev = commits.last.id
+        newrev = commits.first.id
+        wip_commit = wip_merge_request.commits.find(&:work_in_progress?)
+
+        refresh_service.execute(oldrev, newrev, 'refs/heads/wip')
+
+        expect(wip_merge_request.reload.notes.last.note).to eq(
+          "marked as a **Work In Progress** from #{wip_commit.id}"
         )
       end