Cannot capture UpdateExpression like ++foo #32

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1. falsandtru

   changed the title [-]Incorrect increment/decrement assertion messages[/-] [+]Incomplete increment/decrement assertion messages[/+] on Nov 9, 2015
2. twada commented on Nov 9, 2015

   

   twada

   on Nov 9, 2015

   Member

   More actions

   Hi, thank you for reporting.

   Unfortunately, it's a limitation of power-assert. I cannot support UpdateExpression since it causes ReferenceError.

   Let me explain. Given example.js,

   'use strict';
   
   function capt (val) {
       return val;
   }
   
   var counter = {
       count: 0
   };
   
   console.log(++counter.count); // => 1
   console.log(capt(++capt(capt(counter).count)));  // => ReferenceError

   results in ReferenceError when executed.

   $ node example.js
   1
   ~/src/github.com/power-assert-js/power-assert/example.js:12
   console.log(capt(++capt(capt(counter).count)));
                      ^
   ReferenceError: Invalid left-hand side expression in prefix operation
       at Object.<anonymous> (~/src/github.com/power-assert-js/power-assert/example.js:12:20)
       at Module._compile (module.js:460:26)
       at Object.Module._extensions..js (module.js:478:10)
       at Module.load (module.js:355:32)
       at Function.Module._load (module.js:310:12)
       at Function.Module.runMain (module.js:501:10)
       at startup (node.js:129:16)
       at node.js:814:3
   $
   

   capt function is what power-assert is doing internally, so when I tried to capture UpdateExpression like ++foo, it always result in ReferenceError.

   Since test tool should not change behavior of SUT (System Under Test), I gave up supporting UpdateExpression.

   Sorry for inconvenience. I'll write about this limitation to FAQ section in REAME. Thanks!
3. twada

   closed this as completedon Nov 9, 2015
4. twada

   added a commit that references this issue on Nov 9, 2015

   docs(README): add `Incomplete increment/decrement assertion messages?…

   ...

   6e36724
5. falsandtru commented on Nov 9, 2015

   

   falsandtru

   on Nov 9, 2015

   ContributorAuthor

   More actions

   I understand, thanks!
6. twada

   changed the title [-]Incomplete increment/decrement assertion messages[/-] [+]Cannot capture UpdateExpression like ++foo[/+] on May 28, 2016
7. twada

   added

   wontfix

   on Jun 10, 2016