SyncEmitter produce output in debug mode

[cadic]

Describe the bug

Initially reported in Mather-Sophi/sp-debug-bar-for-sophi#13

Happens when

sophi_tracker_emitter_debug is true (f.e. using Debug Bar for Sophi plugin)
AND
The directory vendor/snowplow/snowplow-tracker/debug isn't writable

When the SyncEmitter being created with $debug = true attribute, it will also try to write logs in the hardcoded path:

https://github.com/snowplow/snowplow-php-tracker/blob/32a08e9a7c25d1c51621751e1cdfcffcdef6cfe5/src/Emitter.php#L377-L379

If the path is not writable, Emitter will print the debug information

https://github.com/snowplow/snowplow-php-tracker/blob/32a08e9a7c25d1c51621751e1cdfcffcdef6cfe5/src/Emitter.php#L60-L65

Steps to Reproduce

Refer to the initial report: Mather-Sophi/sp-debug-bar-for-sophi#13

Screenshots, screen recording, code snippet

No response

Environment information

No response

WordPress information

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[cadic]

I see 2 possible solutions:

1. Extend SyncEmitter

class SophiEmitter extends Snowplow\Tracker\Emitters\SyncEmitter {
    const DEBUG_LOG_FILES = false;
}

then replace SyncEmitter with SophiEmitter here:

https://github.com/globeandmail/sophi-for-wordpress/blob/93e5495bae6b0222ef0034c3af18e761f39680ca/includes/functions/content-sync.php#L214

2. Suppress all output in debug mode

Add a conditional ob_start / ob_end_clean wrapper for $tracker->trackUnstructEvent in:

https://github.com/globeandmail/sophi-for-wordpress/blob/93e5495bae6b0222ef0034c3af18e761f39680ca/includes/functions/content-sync.php#L148

[cadic]

Solution 1 will not work: the Snowplow\Tracker\Emitter is using self::DEBUG_LOG_FILES to read the const, in this case it always be true, as it was initially set in the parent class declaration

if (self::DEBUG_LOG_FILES) {
	if ($this->initDebug($type) !== true) {
		$this->write_perms = false;
		print_r("Unable to create debug log files: invalid write permissions.");
	}
}

[cadic]

Looks like it's still possible to extend SyncEmitter and overload it's makeDir and other file methods to fake write failure since we don't want any uncontrolled logging from the 3rd party.

[cadic]

So, as the result, we need to combine both solutions:

1. Extending SyncEmitter with overloaded file methods will suppress writing log files if the vendor/snowplow/snowplow-tracker/debug is writable
2. Adding ob_start / ob_end_clean wrapper for $tracker->trackUnstructEvent() will suppress stdout if the directory is not writable.

[jeffpaul]

@cadic great triage on this, similarly confirming this also impacts publishing (not just updating as Mather-Sophi/sp-debug-bar-for-sophi#13 notes)