The Playwright Pie in the Sky: Solving for CI Blindspots in Microfrontend Architecture in a Crunch

At a previous job, the product team introduced a business-critical microfrontend with module federation to an already bloated tech stack. As a quality engineer, the author was both excited and apprehensive about this new challenge. The remote repo, which contained the microfrontend, was not covered by E2E Playwright tests initially, which raised concerns for the quality engineer.

The author decided to create a spike task to investigate the situation and ensure that the remote repo was properly tested before it was merged into the main codebase. The main issue with testing the microfrontend was that E2E Playwright tests needed to be run in the host app to capture the full user flow, but the host app's CI infrastructure did not support mounting the remote app.

This created a dilemma between adding the E2E tests to the host app, which would require additional infrastructure and code review, or leaving the remote app untested and potentially introducing bugs into the user flow. The author identified five major risk scenarios with this structure, including the possibility of a bug in the remote app going undetected by the host app's CI, or a bug in the host app breaking the remote app when it was deployed.

The author concluded that the tests needed to be added to the host app, as keeping them in the remote repo would result in unnecessary code review and deploy overhead.