Bugfix Issue 1863 tcEdit Absent Tcase List Warning

Bugfix Issue #1863 — tcEdit.php: absent tcase_id logged 4 E_WARNING from buildDirectWebLink() list() destructure

Class of defect: an unguarded PHP 8 list() destructure over the empty array that testcase::getExternalID() contractually returns for a test case that does not exist. The page itself was healthy (HTTP 200, 0 bytes); the only symptom was Event-Viewer pollution — 4 E_WARNING rows per request, forever, for any absent id.

Symptom

Opening the test-case editor for an absent tcase_id (GET /lib/testcases/tcEdit.php?tcase_id=999999) returned HTTP 200 with an empty body but wrote 4 rows to the events table, all at log_level=2:

E_WARNING  Undefined array key 0 - in .../lib/functions/testcase.class.php - Line 5700
E_WARNING  Undefined array key 1 - in .../lib/functions/testcase.class.php - Line 5700
E_WARNING  Undefined array key 2 - in .../lib/functions/testcase.class.php - Line 5700
E_WARNING  Undefined array key 3 - in .../lib/functions/testcase.class.php - Line 5700

Root cause

1. lib/testcases/tcEdit.php:647-652 — whenever $argsObj->tcase_id > 0, the editor builds a context object and calls $tcaseMgr->buildDirectWebLink($webLinkContext).
2. lib/functions/testcase.class.php:5692 buildDirectWebLink() → :5700 list($external_id,$prefix,$glue,$tc_number) = $this->getExternalID($id,$tproject_id); — a 4-element list() destructure with no guard on the returned array.
3. lib/functions/testcase.class.php:5717 getExternalID() → :5734-5735 if (is_null($info)) { return []; } — a test case that does not exist has no get_last_version_info(), so the method deliberately returns an empty array.
4. PHP 8 raises one E_WARNING "Undefined array key N" per missing list() element (4 keys → 4 warnings); TestLink's error handler logs each at log_level=2.

This is latent and independent of the page logic: the empty-array contract of getExternalID() is long-standing, but PHP 7 reported the missing keys only as a notice, whereas PHP 8 reports each as an E_WARNING.

Fix (minimal, 1 site)

lib/functions/testcase.class.php:5700-5707 — capture the array and return '' when it is not a full 4-tuple before destructuring:

$ext = $this->getExternalID($id,$tproject_id);
// getExternalID() returns an empty array for a test case that does not exist;
// destructuring it with list() would emit E_WARNING 'Undefined array key 0..3'
// on PHP 8 (issue #1863). There is no link to build in that case.
if (!isset($ext[3])) {
  return '';
}
list($external_id,$prefix,$glue,$tc_number) = $ext;

This mirrors the guard already used by lib/functions/markdown_tc_export.class.php:322 (isset($arr[3]) && intval($arr[3]) > 0), the repository convention for this contract.

Alternative rejected: making getExternalID() always return a 4-tuple would change the empty-detection semantics its direct [0] consumers rely on (testcase.class.php:10439/10548, testcaseCommands.class.php:213, xmlrpc.class.php:3647/3950, containerEdit.php:1343) — a larger blast radius than the reported defect warrants.

Verification (fresh DB, fixture php tmp/fixtures_1859.php)

#	Step	Expected	Observed	Verdict
1	pre-fix (guard reverted): GET tcEdit.php?tcase_id=999999 then scan events	4 × E_WARNING Undefined array key 0..3 @ line 5700	exactly 4 rows @ 5700	PASS
2	post-fix: same request	HTTP 200, 0 bytes, 0 new events	http=200 bytes=0, 0 rows	PASS
3	GET tcEdit.php?tcase_id=3 (no active version)	200, 0 new events	200 0, 0 rows	PASS
4	GET tcEdit.php?edit_tc=1&tcase_id=6 (active)	200, renders TC1859-ACTIVE, 0 new events	200 18686, name present	PASS
5	buildDirectWebLink(id=6,tp=1)	valid link	/linkto.php?tprojectPrefix=TC1859&item=testcase&id=TC1859-2	PASS
6	buildDirectWebLink(id=999999,tp=1)	''	''	PASS
7	php -l lib/functions/testcase.class.php	no syntax errors	No syntax errors detected	PASS

Gate: TLU_REQUIRE_SUITE="Issue #1863" bash ai/verify_test_suites.sh → 7 PASS / 0 FAIL. Suite: Regression — Issue #1863 in tmp/TLU_Test_Cases.md (9 cases).

Files changed

• lib/functions/testcase.class.php — guard in buildDirectWebLink() (landed as e89fd57c0).
• tmp/TLU_Test_Cases.md — regression suite (append-only).
• docs/ mirror + GitHub Wiki page + CHANGELOG line.

Screenshot

Event Viewer after the fix and after re-issuing GET /lib/testcases/tcEdit.php?tcase_id=999999: no new Error/Warning rows (the pre-fix run wrote 4 E_WARNING Undefined array key 0..3).