Investigate Cypress failure PR comment

[GCHQ-Developer-530]

Summary

At the moment, no matter how the Cypress tests fail, it comments on the PR saying "Visual tests failed". However, in some cases the visual tests haven't failed and the PR comment links to pages that don't exist.

💬 Description

This ticket would be to see if there's a way to determine what the error message is for the failed Cypress tests and only add the PR comment if it talks about test thresholds etc.

Why do we need it?

It would just be nice to have so we don't have redundant PR comments lying about.

Additional notes

Also not sure if this is possible, but it would be good if the PR comment alerting to the failed visual tests deleted itself after a push (or when the cypress tests run again)

[GCHQ-Developer-530]

It does seem that this might be possible, I've found this example -

- name: Run Cypress tests
        id: run_cypress_tests
        run: |
          set -o pipefail
          npm run cypress:run 2>&1 | tee cypress_output.txt || exit 1

      - name: Check for specific error message
        id: check_error_message
        run: |
          if grep -q "specific error message" cypress_output.txt; then
            echo "::set-output name=error_message::true"
          else
            echo "::set-output name=error_message::false"
          fi

And then we'd just need a check for steps.check_error_message.outputs.error_message == 'true'

"specific error message" here would presumably be about test thresholds
and error_message would probably be visual_tests_failed