anchor.diff:      expect(actual.nullabilitySuffix, NullabilitySuffix.none);
     }
   }
  -
  -abstract class _NullableBase with ElementsTypesMixin {
  -  @override
  -  TypeProvider typeProvider;
  -
  -  TypeSystemImpl typeSystem;
  -
  -  FeatureSet get testFeatureSet {
  -    return FeatureSet.forTesting();
  -  }
  -
  -  void setUp() {
  -    var analysisContext = TestAnalysisContext(
  -      featureSet: testFeatureSet,
  -    );
  -    typeProvider = analysisContext.typeProviderLegacy;
  -    typeSystem = analysisContext.typeSystemLegacy;
  -  }
  -}
  
positive.code: }
  
  @reflectiveTest
  class IsPotentiallyNullableTest extends _NullableBase {
    void isNotPotentiallyNullable(DartType type) {
      expect(typeSystem.isPotentiallyNullable(type), isFalse);
    }
  
negative.code: }
  
  @reflectiveTest
  class IsStrictlyNonNullableTest extends AbstractTypeSystemNullSafetyTest {
    void isNotStrictlyNonNullable(DartType type) {
      expect(typeSystem.isStrictlyNonNullable(type), isFalse);
    }
  