<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=29084) </details> <!--IssueSummary end--> We should use the dedicated schema matcher `expect ... match_schema('entities/merge_request_widget')` for excercising serialized JSON at Merge request Widget endpoint. --- The following discussion from gitlab-ce!28595 should be addressed: - [ ] @ayufan started a [discussion](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28595#note_175767044): (+2 comments) > Do we have schema matcher for these parameters? Can we ensure that they are set?