Forum Discussion

ryank's avatar
ryank
Occasional Contributor
9 years ago

Cross-Unit JScript Exceptions

I read in the SmartBear documentation here: Handling Exceptions in Scripts that TestComplete handles cross-unit exceptions in JScript except in certain cases. I followed another link to JScript Speci...
joseph_michaud's avatar
joseph_michaud
Moderator

Well, this is still part the same kind of problem:  You are defining an anonymous function in UnitA and trying to call it from UnitB (func.apply).  You can see this if you try defining similar anonymous functions in the two units:

 

 

// UnitA:
function anonA() { throw new Error("anonA"); }

// UnitB:
function anonB() { throw new Error("anonB"); }

 

 

and then call them from main

 

function main()
{
  doSomething(anonB);
  doSomething(anonA);
}

 

Edit:

To finish the thought...  the exception handling for anonB() works because the function is defined in UnitB and you're calling it from UnitB.  The exception handling for anonA() fails because the function is defined in UnitA and you're calling it from unitB  . . . the exception handling crosses unit boundaries.

 

ryank's avatar
ryank
Occasional Contributor
9 years ago

To continue this though, it seems like sometimes exception handling will work across multiple units for instance, if I did the following:

 

Unit A:

//USEUNIT UnitB

function main(){
  try{
    doSomething();
  }catch(e){
    Log.Message(e.description)
  }
}

Unit B:

function doSomething(func){
    throw new Error("Test");
}

The error is caught properly again. The exception is thrown across the script unit boundary but still gets caught. So I was wondering what exactly gets caught between scripts and what does not

  • joseph_michaud's avatar
    joseph_michaud
    Moderator
    9 years ago

    Ah! I remember now... I had worked a case previously.  The issue seems to be that we can handle exception propagation with direct calls to remote functions but not through copies or references.  So while this would work:

     

    //USEUNIT UnitB
function main()
{
  try {
    doSomething();  // This is direct
  } catch(e) {
    Log.Message(e.message);
  }
}

     

    this would not:

     

    //USEUNIT UnitB
function main()
{
  try {
    var fn = doSomething;  // indirect
    fn();  // Microsoft JScript runtime error
  } catch(e) {
    Log.Message(e.message);
  }
}

     

    The only workaround I could come up with at the time was to make the call to the remote function in a try/catch from within the remote unit (assuming you know where it is...) and provide callbacks to the handle the catching code.

     

     

    //USEUNIT UnitB
function main()
{
  var fn = doSomething;
  remotecall( fn, catchfunc );  // call the function from its own unit
}

function catchfunc(e) { Log.Message(e.description); }


//UnitB
function remotecall( fn, catchfunc )
{
  try {
    fn();
  } catch(e) {
    catchfunc();
  }
}

function doSomething()
{
  throw new Error("doSomething");
}

     

    Not a pretty hack.

     

    I urge you to submit a feature request or add your vote to any existing feature request to see if the developers can get this fixed.