Improving test coverage for HiveServer2

[Ashutosh Chauhan <ha...@apache.org>]

First, I would like to thank Prasad Mujumdar for his recent contributions
of MiniHS2 and MiniKDC. Those are awesome test infra components to make
testing easier for HS2 and kerberos. Thanks, Prasad!

With that checked in now in our repo, we can start making use of those to
improve our test coverage. There are variety of new features which have
landed recently in trunk for HS2 like http transport, pluggable
authentication, new authorization model to name a few. There are test cases
for these in isolation, but not in combination of other features. e.g, HS2
running on http transport with new auth model with kerberos authentication.
Or, HS2 running in binary mode with LDAP authentication. So on and so
forth. I don't have good sense which all combinations we want to support
and thus test. But for atleast those which we do want to support, seems
like its possible to write tests for those using MiniHS2 & MiniKDC. I think
we can take our existing tests in TestJdbcDriver2 (possibly with little
refactoring) and run it against MiniHS2 in various server configurations.

Also, we have TestBeelineDriver, which is currently turned off by default.
Shall we turn it on? I think it can tests at various level of concurrency.
May be to begin with we can set concurrency level at 1 and if things look
good bump that number higher up.

Thoughts?

Thanks,
Ashutosh