A frontend test that prints FAIL is a test that produces a bug report nobody can file. The report needs the URL, the assertion, and the observed value. Those three are enough to open an issue and start a fix.
About 1 min of reading
Add the report format to a suite
Print the three fields
Before you run it, say out loud what it will print. Then open the answer.
Collect instead of stopping
Before you run it, say out loud what it will print. Then open the answer.
Print the totals
Before you run it, say out loud what it will print. Then open the answer.
Confirm the exit code
Before you run it, say out loud what it will print. Then open the answer.
The same place as every other test run, so a frontend failure is not a different kind of thing to notice.
Do not stop on the first failure in a suite. Collect all failures and exit non-zero at the end, so one run names every breakage.
URL, expected, observed. A failure without the observed value cannot be compared to what the browser shows.
One line each, so the output can be pasted into an issue. A stack trace from a crawl names nothing actionable.
Print the pass count and the total. A suite that prints nothing on success is indistinguishable from a suite that did not run.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.