test: add channel random circuit coverage

[arnavnagzirkar]

Adds regression coverage for random circuit generation with include_channels=True.\n\nThe new tests assert that generated random circuits contain at least one supported channel operation and remain serializable via util.convert_to_tensor.

[gemini-code-assist]

Code Review

This pull request adds two new unit tests, test_random_circuit_resolver_batch_channels_present and test_random_symbol_circuit_resolver_batch_channels_present, to verify that channel operations are included in generated circuits when include_channels=True and that the resulting circuits are serializable. The reviewer recommends strengthening the serialization checks in both tests by performing a full round-trip serialization and deserialization verification instead of only asserting that the serialized output is not null.

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[gemini-code-assist]

Asserting assertIsNotNone on the result of util.convert_to_tensor only verifies that the serialization function does not raise an exception. It does not guarantee that the channels are correctly serialized and can be deserialized back without data loss or corruption. Performing a round-trip serialization and deserialization check provides a much stronger correctness guarantee.

Suggested change

	# Verify circuits containing channels are serializable.
	self.assertIsNotNone(util.convert_to_tensor(circuits))
	# Verify circuits containing channels are correctly serializable round-trip.
	serialized = util.convert_to_tensor(circuits, deterministic_proto_serialize=True)
	deserialized = util.from_tensor(serialized)
	self.assertAllEqual(
	serialized,
	util.convert_to_tensor(deserialized, deterministic_proto_serialize=True))

[gemini-code-assist]

Asserting assertIsNotNone on the result of util.convert_to_tensor only verifies that the serialization function does not raise an exception. It does not guarantee that the channels are correctly serialized and can be deserialized back without data loss or corruption. Performing a round-trip serialization and deserialization check provides a much stronger correctness guarantee.

        # Verify circuits containing channels are correctly serializable round-trip.
        serialized = util.convert_to_tensor(circuits, deterministic_proto_serialize=True)
        deserialized = util.from_tensor(serialized)
        self.assertAllEqual(
            serialized,
            util.convert_to_tensor(deserialized, deterministic_proto_serialize=True))