anchor.diff:  }
   ''');
   
  -    assertConstraint([decoratedTypeAnnotation('C c').node.nullable],
  -        checkExpression('c.m').nullCheck);
  +    assertNullCheck(
  +        checkExpression('c.m'), decoratedTypeAnnotation('C c').node);
     }
   
     test_methodInvocation_target_demonstrates_non_null_intent() async {
  
positive.code: int f(int i, int j) => i + j;
  ''');
  
      assertConstraint([decoratedTypeAnnotation('int i').node.nullable],
          checkExpression('i +').nullCheck);
    }
  
    test_binaryExpression_add_left_check_custom() async {
  
negative.code:     var nullable_i = decoratedTypeAnnotation('int i').node.nullable;
      var nullable_j = decoratedTypeAnnotation('int j').node.nullable;
      var nullable_i_or_nullable_j = _either(nullable_i, nullable_j);
      var nullable_conditional = decoratedExpressionType('(b ?').node;
      var nullable_return = decoratedTypeAnnotation('int f').node;
      assertConstraint([nullable_i], nullable_conditional.nullable);
      assertConstraint([nullable_j], nullable_conditional.nullable);
      assertConstraint([nullable_conditional.nullable], nullable_i_or_nullable_j);
      assertNullCheck(checkExpression('(b ? i : j)'), nullable_conditional,
          contextNode: nullable_return);
    }
  
    test_conditionalExpression_left_non_null() async {
  