auto_test/toxav_basic_test.c wrong assertion

[sudden6]

In https://github.com/TokTok/c-toxcore/blob/master/auto_tests/toxav_basic_test.c#L87 the return value is checked agains -1 which is not defined according to https://github.com/TokTok/c-toxcore/blob/master/toxcore/tox.h#L1321 Possibly others are affected.

IMHO we should define the return value in the error case to UINT32_MAX, but at least the testcase needs to be updated.

[JFreegman]

Since the return value is undefined it should be ignored when err != ok. I don't think we need to change the API, rather just fix the assert.

[sudden6]

For a quick fix, yes the assert should be updated, longer term I think changing the API with the next API break is cleaner.

[JFreegman]

Actually it's not an API break. We wouldn't be changing the API's behaviour, just defining what it already does. I have no issue with that. But if we're going to do it we should be consistent across the entire API.

[iphydf]

I agree, it's not an API break. When we defined the API, we intentionally left these undefined, but it probably makes sense to reserve UINT32_MAX for error values (C++ does this for example in std::string::npos).