Problem with using arrow functions

Dear community, am having bit of an issue using arrow function defined in another file. Code snippet is below.  Looking forward to any hints.

Test1.JS
-------------
const str = 'xyz';
const getStr = () => str;

Test2.JS
-------------
//USEUNIT Test1
function test() {
  Log.Message(Test1.getStr());
}

I get an error at the statement where Test1.getStr() is called.
  JavaScript runtime error.
  TypeError: Test1.getStr is not a function

If I modify Test1.JS to the below lines, it then starts working.
const str = 'xyz';
getStr = () => str;  //notice that I have removed const

Any idea what am missing? Did I hit a limitation in TestComplete?  BTW, if the arrow function and the caller are in the same JS file, it works with no issues.

Best Regards,
Madhu