Have you checked there are no test about that for now?

Have you checked there are no test about that for now?

Yes. I could find nothing that explicitly, or properly, checks dealing with mixed bin/str elements in MessagePack protocol stream.

More detail...

A proper test for this requires:

1. testing a raw MessagePack byte sequence with mixed bin/str types in it
2. explicit testing of the symmetry when using use_bin_type=True and raw=False
3. assertion of identical python types (not just equality testing with ==)
4. testing properly under both python 2 and python 3

The closest I could find (that do not meet these criteria) are:

• tests in test_case.py
  • No tests for mixed bin/str types. They also don't test any use_bin_type usage. They also use equality testing with == which does not ensure type matches.
• test_stricttype.test_tuple seems like, at first glance, that it kind of checks it... but it doesn't meet the criteria
  • it does partially cover the condition under python 3 (the right pack/unpack sequence happens to happen there), but there is no explicit byte stream specified, and it doesn't meet several other other criteria (eg: no type checking, doesn't properly cover python2, etc). In addition, the fact that it happens to do a piece of the test is mostly by accident, since it is not the purpose of the test.
• test_pack.py and test_unpack.py also don't have anything that properly tests it

With a lack of an explicit test, I thought one should be added, so I wrote it rather than requested it. Note that I also considered writing a test case with multiple cases (similar to what test_case.test_match does), but ended up thinking that a clean single case test for the specific conditions was better.

Also - I renamed the test to better reflect what it does. The original name wasn't great.

Mixed testing should not be necessary. Packing/unpacking does not change internal state of the Packer/Unpacker beyond managing message buffers. As long as each object/token is handled correctly any mix of types will be handled correctly.
That said there are some issues with the current test suite. E.g., this assert test_pack.py#L15 is not triggered if given str and unicode in Python 2.7. This type of assert is used in several tests.
Also, a lot of tests use some form of packing-unpacking chain. Regressions in the Packer can be hidden by regressions in the Unpacker. They should probably be rewritten in the style of test_format.py: specifying the ground-truth data-object pair as per msgpack spec that to be handled correctly.