bug(trace-viewer): update trace file on trace viewer when test completes

[ruifigueira]

Fixes microsoft/playwright#31314

[pavelfeldman]

I don't think the error that you see in console is related to the behavior that you are changing. What's the idea behind this change, could you verbalize it?

[ruifigueira]

This change updates the trace displayed in the trace viewer when a test in a multiple test run completes (basically, it replaces the live json trace file, which is being polled during live mode, with the final zip trace file). Otherwise, VSCode TraceViewer instance doesn't send the new trace file to _traceViewerProcess, which will continue to send loadTraceRequested messages via websocket to the traceviewer webapp with the old json trace path.

In my tests, it fixed the issue.

[ruifigueira]

BTW, the reason why it works with one single test running and fails with more than one is because enqueuedSingleTest is true and so it calls the showTrace:

https://github.com/microsoft/playwright-vscode/blob/main/src/extension.ts#L486-L487

The check I added there is just to ensure that the trace viewer is showing the trace for the right test item. If they are the same, the trace viewer must be displaying the old trace value that is now being updated.

[pavelfeldman]

Otherwise, VSCode TraceViewer instance doesn't send the new trace file to _traceViewerProcess, which will continue to send loadTraceRequested messages via websocket to the traceviewer webapp with the old json trace path

That's normal behavior for the case of live traces - we race with the trace provider here, so it is Ok for the files to not be there. I understand that you are removing a case where update is hammering against the missing file, but the JSON error will still be happening in other cases. I'd suggest that you change the title of the PR to reflect the actual change.