6 files declare their use of OffCanvasTestBase

AccessAnnouncementTest.php in core/modules/announcements_feed/tests/src/FunctionalJavascript/AccessAnnouncementTest.php
AccessAnnouncementTest.php in core/modules/toolbar/tests/src/FunctionalJavascript/announcements_feed/AccessAnnouncementTest.php
AlertsJsonFeedTest.php in core/modules/announcements_feed/tests/src/FunctionalJavascript/AlertsJsonFeedTest.php
SettingsTrayTestBase.php in core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayTestBase.php
WorkspaceToolbarIntegrationTest.php in core/modules/workspaces_ui/tests/src/FunctionalJavascript/WorkspaceToolbarIntegrationTest.php
WorkspaceToolbarIntegrationTest.php in core/modules/toolbar/tests/src/FunctionalJavascript/workspaces_ui/WorkspaceToolbarIntegrationTest.php

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