[PyTorch FE] Bug: _is_testing() always returns True for truthy inputs due to missing .lower() call

[rishi-sangare]

Problem

In backend_utils.py:86, the _is_testing() function compares a method reference instead of calling it:

def _is_testing(options) -> Optional[Any]:
    if options is not None and "testing" in options:
        is_testing = options["testing"]
        if bool(is_testing) and str(is_testing).lower not in ["false", "0"]:
            return True
    return False

str(is_testing).lower is a bound method object — it's never equal to "false" or "0", so the not in check always evaluates to True. This means any truthy value of options["testing"], including the string "false" or "0", will cause the function to return True.

Impact

_is_testing() is used in partition.py:138 to set allow_single_node_partition. Because the flag check is broken, passing {"testing": "false"} or {"testing": "0"} still enables testing mode, which changes partitioning behavior unexpectedly.

Fix

- if bool(is_testing) and str(is_testing).lower not in ["false", "0"]:
+ if bool(is_testing) and str(is_testing).lower() not in ["false", "0"]:

I can submit a PR for this.

[rishi-sangare]

.take