Bugfix: Issue #813 — GitHub connect button always reports "OAuth not configured" on a fresh install

Summary

On a fresh TestLink 2.0.1 install the GitHub connect button on the Issue Trackers screen (gui/templates/issuetracker/issuetrackerView.html) always alerted:

GitHub OAuth is not configured (missing oauth_client_id/oauth_client_secret)

The GitHub issue/BTS integration was unreachable out of the box: the required OAuth credentials were never collected anywhere and no local config file was produced by the installer.

Root Cause

1. api/issuetracker/index.php:151-171 — gh_oauth_config() is the single source of truth for GitHub OAuth credentials for the Issue Tracker. It returns null whenever cfg/oauth_github_local.inc.php is missing, not loadable, or holds empty/CHANGE_* placeholder values.
2. api/issuetracker/index.php:255-260 (GET /oauth/start) and :279-284 (/oauth/callback) short-circuit to HTTP 503 with the "not configured" message whenever gh_oauth_config() is null.
3. gui/templates/issuetracker/issuetrackerView.html:263-281 — githubOAuthStart() alert()s the server message on the error path.
4. The config file was never produced: the 1.9.20-era installer (install/installDbInput.php / install/installNewDB.php) had no GitHub OAuth fields and never wrote cfg/oauth_github_local.inc.php. So every fresh install ran with null config and the button hard-failed.

Blast radius: the affected code is confined to the GitHub-OAuth paths of api/issuetracker/index.php and its only modernized client (gui/templates/issuetracker/issuetrackerView.html). The login-page OAuth subsystem (login.php, api/auth/index.php, lib/functions/oauth_api.php) reads the same $tlCfg->OAuthServers map for authentication providers but is independent: an absent local config file changes nothing there.

Fix

Issue #813 was implemented by commit b767d45c0 (feat(install): collect GitHub OAuth credentials at install time and generate local config, already on the default branch). No backend change was needed — gh_oauth_config() already reads cfg/oauth_github_local.inc.php:

1. Installer form (install/installDbInput.php:215-242, gated on new installs $_SESSION['isNew']): optional "GitHub OAuth" section with an enable checkbox, oauth_client_id and oauth_client_secret fields, plus a hint showing the required Authorization callback URL (/api/issuetracker/index.php/oauth/callback).
2. Config generation (install/installNewDB.php:679-713, write_oauth_github_config(), invoked at :570): copies the POSTed values through $_SESSION (installNewDB.php:46-53), validates them (rejects CHANGE_* placeholders, skips silently when disabled/empty), and writes cfg/oauth_github_local.inc.php with mode 0600.
3. Documentation (cfg/oauth_github_local.inc.php.example): documents the manual path (copy to cfg/oauth_github_local.inc.php, replace placeholders) and where to create the OAuth App.
4. Because the local file is gitignored (.gitignore:54), secrets can never be committed.

Verification (measured)

Reproduced on http://localhost:8082 (admin session, fresh DB import):

• Pre-config: GET /api/issuetracker/index.php/oauth/start → HTTP 503 {"status":"error","message":"GitHub OAuth is not configured (missing oauth_client_id/oauth_client_secret)"}; clicking GitHub alerts the same.
• Post-config (config file in the exact format write_oauth_github_config() emits): GET /oauth/start → HTTP 200 {"status":"ok","url":"https://github.com/login/oauth/authorize?client_id=…"} and the UI button opens a real GitHub authorize popup (no alert).

• Generated-file format validated standalone: php -l clean; loads into $tlCfg->OAuthServers['github'] exactly as gh_oauth_config() expects; file mode 600.
• Event Viewer: no new Error/Warning rows from the flow.

When credentials are genuinely missing the button still warns — that is the intended behaviour after the fix.

Commits: b767d45c0 (fix, default branch). Regression suite: tmp/TLU_Test_Cases.md Suite 818 (12/12 PASS).