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A fake WKNavigation was killing the test host, hiding a whole suite #8633

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Merged
austinywang merged 2 commits into from
Aug 4, 2026
Merged

A fake WKNavigation was killing the test host, hiding a whole suite #8633

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a65ff73
cmuxTests: stop a fake WKNavigation from killing the test host
ejc3 Jul 22, 2026
34c2460
cmuxTests: the same suite closes a test-owned window AppKit also rele…
ejc3 Jul 22, 2026
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35 changes: 30 additions & 5 deletions cmuxTests/BrowserDiscardRestoreHealPredicateTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -202,6 +202,26 @@ struct BrowserDiscardRestoreHealPredicateTests {

}

/// WebKit constructs a `WKNavigation`'s embedded C++ `API::Navigation` itself, so an instance
/// made with a bare `WKNavigation()` carries unconstructed storage. Allocating one is harmless;
/// releasing it is not — `-[WKNavigation dealloc]` traps, which kills the whole xctest host
/// rather than failing a test, and takes every suite sharing that host down with it. Reproduced
/// directly outside the test bundle: EXC_BREAKPOINT inside CFRetain from that dealloc with WebKit
/// initialised, and SIGSEGV via WebCoreObjCScheduleDeallocateOnMainRunLoop without it.
///
/// The discard-restore bookkeeping under test only ever compares these by identity, so minting
/// them here and holding them for the run is behaviour-preserving and keeps the host alive.
@MainActor
private enum BrowserDiscardRestoreNavigationStub {
private static var retained: [WKNavigation] = []

static func make() -> WKNavigation {
let navigation = WKNavigation()
retained.append(navigation)
return navigation
}
}

private final class BrowserDiscardRestorePolicyCancelAlert: NSAlert {
var response: NSApplication.ModalResponse = .alertThirdButtonReturn

Expand Down Expand Up @@ -240,7 +260,7 @@ struct BrowserDiscardRestorePolicyCancelTests {
now: Date(timeIntervalSince1970: 100)
)
panel.hiddenWebViewDiscardManager.noteRestoreNavigationStarted(reason: "test.restore")
panel.pendingDiscardRestoreNavigation = WKNavigation()
panel.pendingDiscardRestoreNavigation = BrowserDiscardRestoreNavigationStub.make()

#expect(panel.restoreDiscardedWebViewIfNeeded(reason: "test.reveal"))

Expand Down Expand Up @@ -275,8 +295,8 @@ struct BrowserDiscardRestorePolicyCancelTests {
@Test func staleRestoreCancelDoesNotClearCurrentAttemptedRequest() throws {
let staleURL = try #require(URL(string: "https://example.com/cmux-issue-7504-stale"))
let currentURL = try #require(URL(string: "https://example.com/cmux-issue-7504-current"))
let staleNavigation = WKNavigation()
let currentNavigation = WKNavigation()
let staleNavigation = BrowserDiscardRestoreNavigationStub.make()
let currentNavigation = BrowserDiscardRestoreNavigationStub.make()
let panel = BrowserPanel(
workspaceId: UUID(),
initialURL: nil,
Expand Down Expand Up @@ -445,6 +465,11 @@ struct BrowserDiscardRestorePolicyCancelTests {
backing: .buffered,
defer: false
)
// This test owns the window through ARC, so AppKit must not release it as well when the
// deferred close runs. Leaving the default on drops the last retain while other references
// to that address are still live, which aborts the test host rather than failing a test.
// cmuxTests sets this guard at about seventy other window-closing sites.
window.isReleasedWhenClosed = false
defer {
panel.resetInsecureHTTPAlertHooksForTesting()
window.close()
Expand All @@ -465,7 +490,7 @@ struct BrowserDiscardRestorePolicyCancelTests {
now: Date(timeIntervalSince1970: 300)
)
panel.noteDiscardedWebViewRestoreNavigationStarted()
panel.pendingDiscardRestoreNavigation = WKNavigation()
panel.pendingDiscardRestoreNavigation = BrowserDiscardRestoreNavigationStub.make()
panel.navigationDelegate?.recordAttemptedRequest(URLRequest(url: url))

let alert = BrowserDiscardRestoreDeferredPolicyAlert()
Expand All @@ -477,7 +502,7 @@ struct BrowserDiscardRestorePolicyCancelTests {
let staleCompletion = try #require(alert.completionHandler)

panel.noteDiscardedWebViewRestoreNavigationDidNotCommit(reason: "test.old_cancel")
let currentNavigation = WKNavigation()
let currentNavigation = BrowserDiscardRestoreNavigationStub.make()
panel.noteDiscardedWebViewRestoreNavigationStarted()
panel.pendingDiscardRestoreNavigation = currentNavigation
panel.navigationDelegate?.recordAttemptedRequest(URLRequest(url: url))
Expand Down