If the expect assertion fails, the test execution will halt immediately, and handle.dispose() at the end of the test will not be called. This leaves the global semantics state enabled, which can cause side effects or failures in subsequent tests. Registering the disposal with addTearDown immediately after creation ensures it is always cleaned up properly.

    final SemanticsHandle handle = tester.ensureSemantics();
    addTearDown(handle.dispose);

This is how the test was previously structured, no addTearDown was previously used. Also explanation from gemini below as to why the test fails if we do use addTearDown(handle.dispose).

From gemini:

Flutter's TestWidgetsFlutterBinding runs its end-of-test leak verifications (specifically _verifySemanticsHandlesWereDisposed) inside the test body execution flow, immediately after your test callback completes, but before returning control to the Dart test runner:

1. [Test Runner] Starts test
2.   [Flutter Binding] Runs test body (your async callback)
3.     Your test code executes...
4.     Your test code completes.
5.   [Flutter Binding] Runs _endOfTestVerifications()  <-- CRITICAL POINT
6.     Checking active SemanticsHandles... 
       ERROR: "A SemanticsHandle was active at the end of the test."
7. [Test Runner] Runs addTearDown callbacks            <-- TOO LATE!
8.   handle.dispose() is called here.

Because the verification (Step 5) happens before the test runner runs the teardown callbacks (Step 7), the binding sees that the SemanticsHandle is still active and throws a FlutterError, failing the test.

Since handle.dispose() is now registered via addTearDown right after creation, this manual call at the end of the test is redundant and can be removed.

#11980 (comment)

If the expect assertion fails, the test execution will halt immediately, and handle.dispose() at the end of the test will not be called. This leaves the global semantics state enabled, which can cause side effects or failures in subsequent tests. Registering the disposal with addTearDown immediately after creation ensures it is always cleaned up properly.

    final SemanticsHandle handle = tester.ensureSemantics();
    addTearDown(handle.dispose);

#11980 (comment)

Since handle.dispose() is now registered via addTearDown right after creation, this manual call at the end of the test is redundant and can be removed.

#11980 (comment)

If the expect assertion fails, the test execution will halt immediately, and handle.dispose() at the end of the test will not be called. This leaves the global semantics state enabled, which can cause side effects or failures in subsequent tests. Registering the disposal with addTearDown immediately after creation ensures it is always cleaned up properly.

    final SemanticsHandle handle = tester.ensureSemantics();
    addTearDown(handle.dispose);

#11980 (comment)

Since handle.dispose() is now registered via addTearDown right after creation, this manual call at the end of the test is redundant and can be removed.

#11980 (comment)