Fix truncated Chrome WS URL that results in intermittent Ferrum::DeadBrowserError

[francisbeaudoin]

Details

The Chrome WebSocket URL is read from the IO with the following:

ferrum/lib/ferrum/browser/process.rb

Lines 142 to 150 in a71634d

	begin
	output += read_io.read_nonblock(512)
	rescue IO::WaitReadable
	read_io.wait_readable(max_time - now)
	else
	if output.match(regexp)
	self.ws_url = output.match(regexp)[1].strip
	break
	end

As 512 bytes are read at a time, it occasionally occurs that we get a truncated WebSocket URL. For example, that is the output of the ws_url variable within a CI tests run that failed:

ws://127.0.0.1:35663/devtools/browser/a3603fc2-ed48-497d-9c1e-057b08f83aaf
ws://127.0.0.1:45503/devtools/browser/4db98447-c685-4a71-a7d5-146f2c2f24c5
...
ws://127.0.0.1:33327/devtools/browser/bab2421f-9b04-49af-8a50-e6802c21fa0c
ws://127.0.0.1:36173/devtools/browser/e1b4a3fa-c230-4422-ac82-ecf77858b33f
ws://127.0.0.1:42227/devtools/browser/907bc2f7-20ea-42e2-b1ea
ws://127.0.0.1:45059/devtools/browser/a36c4ddc-e6dc-4e65-bbe6-5d8ecbf653c5
...

As you can see, the ws://127.0.0.1:42227/devtools/browser/907bc2f7-20ea-42e2-b1ea one is truncated which eventually result in the driver raising a Ferrum::DeadBrowserError exception.

Proposed solution

The proposed fix is to enhance the regex by checking that the URL ends with a complete UUID.

Alternative solution

The logic could be changed to read the IO line by line instead of a fixed 512 bytes as Chrome is outputting with line breaks.

[route]

That's interesting, thank you Francis.