Fix EngineProgram.get_circuit(_async) empty code detection

[maffoo]

No description provided.

[pavoljuhas]

Should it be at the second alternative or not self._program.code.value?

The bool(any_pb2.Any()) is True so the middle expression is effectively or False or ...

Also can we add a test that would cover the fixed failure?

[maffoo]

This is mostly defense in depth because I didn't want to rely on the code attribute being set. As for whether we check type_url or value I think either is probably ok. I don't know if valid proto messages can ever have an empty byte representation, but I presume not? Do you have a particular reason to prefer value over type_url?

[pavoljuhas]

If we trust the type annotation self._program can be either None or a QuantumProgram which is guaranteed to have a .code field of the any_pb2.Any type.

I was puzzled because or not self._program.code is effectively or False and thus redundant. I wondered if the intent was to have some non-const expression there so I suggested the value field. Otherwise I have no preference, dropping or not self._program.code would be fine with me too.

[maffoo]

Yes, it's the types of QuantumProgram itself that concerns me, because the proto-plus library does some metaclass magic so it's not clear to me how its type annotations work. I'd prefer to keep this for defense in depth for now.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.57%. Comparing base (2ef9f37) to head (f5a2752).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7850   +/-   ##
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  Coverage   99.57%   99.57%           
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  Files        1104     1104           
  Lines       98988    98990    +2     
=======================================
+ Hits        98566    98569    +3     
+ Misses        422      421    -1     

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[maffoo]

Updated tests to include case with a QuantumProgram with empty code field. PTAL, @pavoljuhas

[eliottrosenberg]

Fixes b/477955102

[pavoljuhas]

LGTM with an optional inline suggestion.