refactor(core): private export token to disable `fixture.detectChange…

…s` error (#55098)

While we do want to discourage `fixture.detectChanges`, it is yet to be
determined how this should be accomplished (warning, documentation, etc.). At
the moment, not being able to disable the error at all is entirely
prohibitive for existing test suites to use zoneless change detection in
tests. We would much rather allow existing test suites to disable the
error and use the zoneless change detection than prevent them from using
it entirely until all the `detectChanges` calls have been fixed.
Calling `detectChanges` manually can hide errors related to change
detection timing, but it is even worse when the "PseudoApplication"
fixture used (since it runs change detection _only_ on the component
rather than through `ApplicationRef`).

PR Close #55098

packages/core/testing/private_export.ts

@@ -0,0 +1,9 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+export {AllowDetectChangesAndAcknowledgeItCanHideApplicationBugs as ɵAllowDetectChangesAndAcknowledgeItCanHideApplicationBugs} from './src/test_bed_common';