Issue 649 — codeTrackerInterface truthiness check falsely treats empty-root XML config as parse failure

Issue: #649 Branch: fix/issue-649 · Commits: cb7238aa3 (fix), 0aead081a (regression suite) Status: FIXED & VERIFIED (2026-08-23)

Symptom

A code tracker saved with a valid but childless-root config (<codetracker></codetracker>, savable since the #432 identity-check fix) produced a spurious ERROR on every interface instantiation and left the integration disconnected:

setCfg() returned: false        ← valid XML reported as failure
connected flag:    false

events table:
id=1 log_level=1(ERROR) source=GUI :: codeTrackerInterface::setCfg - Failure loading XML STRING
id=2 log_level=1(ERROR) source=GUI :: codeTrackerInterface::setCfg - Failure loading XML STRING

Note no libxml error text was appended — because there WAS no parse error.

Root cause chain

1. lib/codetrackerintegration/codeTrackerInterface.class.php:105 — $this->cfg = simplexml_load_string($xmlCfg);
2. :106 — if (!$this->cfg) used TRUTHINESS. PHP casts a SimpleXMLElement wrapping a childless root element to boolean FALSE (measured: (bool)$x === false, $x === false === false). A SUCCESSFUL parse entered the failure branch.
3. :107-113 — $msg = "...Failure loading XML STRING" set with zero libxml errors.
4. :121-124 — !($retval = is_null($msg)) → returns false → tLog(...,'ERROR').
5. Constructor :60-69 — else branch sets $this->connected = false; every code-integration lookup via tlCodeTracker::getInterfaceObject() runs disconnected.

Why now: #432 fixed only the save-time validator tlCodeTracker::checkXMLCfg (lib/functions/tlCodeTracker.class.php:694, $cfg === false). Empty-root configs became savable, making this runtime-side copy of the same latent 1.9.20 pattern reachable for the first time. #432 exposed it; it did not introduce it.

Blast radius

• Direct: every concrete subclass constructor — currently stashrestInterface (the only subclass of codeTrackerInterface). All entry points through tlCodeTracker::getInterfaceObject(): execSetResults.php:753, scriptAdd.php:303, scriptDelete.php:121, archiveData.php:199, print.inc.php:2369, plus BFF paths.
• Same-pattern siblings found during investigation, filed separately as #650: issueTrackerInterface.class.php:117, reqMgrSystemInterface.class.php:81.

Approach — mirror the proven identity check

Chosen fix (one condition + comment):

// was:  if (!$this->cfg)
if ($this->cfg === false)

Identity comparison is the ONLY change that distinguishes "parse failed" (simplexml_load_string returns literal false) from "parsed object that happens to be falsey" (childless root). Rejected alternatives: is_null($this->cfg) (wrong — never null), wrapping in try/catch only (libxml failures return false rather than throwing), or suppressing the log at handler level (hides real failures).

Post-fix behavior for <codetracker></codetracker>: parse succeeds → connect() silently skips (no credentials configured — by design) → no events written.

Files changed

File	Change
lib/codetrackerintegration/codeTrackerInterface.class.php	:106 truthiness → $this->cfg === false (+ explanatory comment)
tmp/TLU_Test_Cases.md	Suite 649 regression entry (5 cases incl. pre-fix repro)

Verification (regression matrix, CLI against live DB)

Case	cfg	setCfg()	connected	new events
R1	<codetracker></codetracker>	true (was false)	false (silent credential skip — by design)	NO bogus ERROR; 3 WARNINGs from unguarded stashrest property reads → pre-existing class filed as #651
R2	full config with children	true	false*	none — unchanged (*unreachable host fails cleanly)
R3	<codetracker< malformed	false (correctly)	false	ERROR WITH libxml detail text ✓

Suite 649: 5/5 PASS (tmp/TLU_Test_Cases.md).

Related issues

• #650 — identical truthiness pattern in issue-tracker and reqmgr sibling interfaces (FIXED).
• #651 — unguarded cfg property reads (stashrestInterface.class.php:47/99/100) warn for incomplete configs; pre-existing, surfaced by this fix's verification matrix (open).