anchor.diff:  Int f(Int i, Int j) => i + j/*check*/;
   ''');
   
  -    assertConstraint(
  -        [decoratedTypeAnnotation('Int j').node.nullable],
  -        _either(decoratedTypeAnnotation('Int other').node.nullable,
  -            checkExpression('j/*check*/').nullCheck));
  +    assertNullCheck(
  +        checkExpression('j/*check*/'), decoratedTypeAnnotation('Int j').node,
  +        contextNode: decoratedTypeAnnotation('Int other').node);
     }
   
     test_binaryExpression_equal() async {
  
positive.code:     var int_1 = decoratedTypeAnnotation('int/*1*/');
      var int_2 = decoratedTypeAnnotation('int/*2*/');
      var i_3 = checkExpression('i/*3*/');
      assertConstraint(
          [int_2.node.nullable], _either(int_1.node.nullable, i_3.nullCheck));
      assertConstraint(
          [int_2.node.nullable, int_1.node.nonNullIntent], i_3.nullCheck);
      assertConstraint([int_1.node.nonNullIntent], int_2.node.nonNullIntent);
    }
  
  
negative.code: }
  ''');
  
      var nullable_b = decoratedTypeAnnotation('bool b').node;
      var check_b = checkExpression('b ?');
      assertNullCheck(check_b, nullable_b);
    }
  
    test_conditionalExpression_general() async {
  