2019592 - NimbusTestUtils._testSuite retains test scope through shutdown, causing window leaks

Status: RESOLVED FIXED

(Firefox :: Nimbus Desktop Client, defect)

Description

[Florian Quèze [:florian]]

NimbusTestUtils.init(this) stores a reference to the test's global scope in a module-level _testSuite variable. Since var declarations in browser chrome tests become properties of the global object, any window references stored in vars are kept alive through shutdown via the chain: ModuleLoaderBase → NimbusTestUtils.sys.mjs → _testSuite → (test global) → window.

This causes shutdown leaks for any test that both uses NimbusTestUtils (via head.js) and stores window references in global vars. For example, browser_site_login_exceptions_policy.js leaks its subdialog windows this way.

The fix is to have NimbusTestUtils.init() register a cleanup function on the test scope that nulls out _testSuite when the test finishes.

Comment 1

[Florian Quèze [:florian]]

The reference paths are visible when hovering the "FAIL" markers in this profile produced with the patches from bug 2019756.

Comment 2

[Florian Quèze [:florian]]

Attachment: Bug 2019592 - Fix shutdown leak in NimbusTestUtils by not retaining test scope, r=#nimbus-reviewers.

NimbusTestUtils.init() stored the entire test global scope in _testSuite,
which retained all var declarations (including window references) through
shutdown. Instead, capture only the Assert instance directly.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/a94ea6683c31
https://hg.mozilla.org/integration/autoland/rev/8bfabdb43012
Fix shutdown leak in NimbusTestUtils by not retaining test scope, r=nimbus-reviewers,beth.

Comment 4

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/8bfabdb43012