anchor.diff:  }
   
   @reflectiveTest
  -class _InstrumentationTest extends AbstractContextTest {
  +class _InstrumentationTest extends _InstrumentationTestBase {
  +  @override
  +  bool get useFixBuilder => false;
  +}
  +
  +abstract class _InstrumentationTestBase extends AbstractContextTest {
     NullabilityNodeInfo always;
   
     final Map<TypeAnnotation, NullabilityNodeInfo> explicitTypeNullability = {};
  
positive.code: main() {
    defineReflectiveSuite(() {
      defineReflectiveTests(_InstrumentationTest);
    });
  }
  
  class _InstrumentationClient implements NullabilityMigrationInstrumentation {
    final _InstrumentationTest test;
  
    _InstrumentationClient(this.test);
  
  
negative.code:         (e) => e.sourceNode == node && e.destinationNode == never && e.isHard);
    }
  }
  
  @reflectiveTest
  class _InstrumentationTestWithFixBuilder extends _InstrumentationTestBase {
    @override
    bool get useFixBuilder => true;
  
    @override
    @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/38472')
    Future<void> test_fix_reason_edge() => super.test_fix_reason_edge();
  
    @override
    @FailingTest(issue: 'https://github.com/dart-lang/sdk/issues/38472')
    Future<void> test_fix_reason_node() => super.test_fix_reason_node();
  }
  