anchor.diff:    }
   
     test_ifNull() async {
  -    await assertNoErrorsInCode(r'''
  -f(int a, double b) {
  +    var question = typeToStringWithNullability ? '?' : '';
  +    await assertNoErrorsInCode('''
  +f(int$question a, double b) {
     a ?? b;
   }
   ''');
  
positive.code: 
  @reflectiveTest
  class BinaryExpressionResolutionWithNullSafetyTest
      extends PubPackageResolutionTest with WithNullSafetyMixin {
    test_ifNull_left_nullableContext() async {
      await assertNoErrorsInCode(r'''
  T f<T>(T t) => t;
  
negative.code: }
  
  @reflectiveTest
  class BinaryExpressionResolutionTest extends PubPackageResolutionTest
      with BinaryExpressionResolutionTestCases {}
  
  mixin BinaryExpressionResolutionTestCases on PubPackageResolutionTest {
    test_bangEq() async {
      await assertNoErrorsInCode(r'''
  f(int a, int b) {
  