How is any(flattened_params) (what we had before) any different from len([param for param in flattened_params if param is not None]) > 0? IIUC any returns True if any of its elements evaluate to True, so removing the Nones (which evaluate to False anyway) would only make a difference if the resulting list has only non-None falsy-objects (where any would have returned False but len(...) > 0 would now return True). What would be a real example of such objects? Could we capture them in a golden file? (I scanned quickly and didn't see one.)

ref: https://docs.python.org/3/library/functions.html#any

Yes, we have non-None, falsy objects. The test_nested_messages.proto that was added to fragment tests is an example of a proto where encounter this problem

There is an example in the stack trace in #2257 (comment)

>           await client.my_method(
                test_nested_messages.MethodRequest(),
                some_message=test_nested_messages.SomeMessage(another_message=None),
            )

Specifically any([test_nested_messages.SomeMessage(another_message=None)]) evaluates to False however test_nested_messages.SomeMessage(another_message=None) is not None evaluates to True

See screen capture from local debugging of the generated fragment client.

OK, I see. That's slightly surprising, but I guess the semantics are that if a message has nothing set, it evaluates as False? That would fit with what you're describing.

Thanks for the explanation!

OK, I see. That's slightly surprising, but I guess the semantics are that if a message has nothing set, it evaluates as False? That would fit with what you're describing.

Thanks for the explanation!