twisted.python.reflect.objgrep test coverage is incomplete

[rwall]

In #6362 Thijs noted that objgrep(showUnknown) is not covered by any tests.

• source:trunk/twisted/python/reflect.py

There are also various objgrep convenience functions which are untested eg modgrep

As it stands, it's difficult to trigger the showUnknowns branch - you'd need to find some object type that is not already handled.

I thought about adding a special type which would never be recognised and which could be passed in for testing purposes.

• ​https://buildbot.twistedmatrix.com/builds/twisted-coverage.py/twisted-coverage.py-r38404/twisted_python_reflect.html#n504

[therve]

objgrep and modgrep are good candidates for deprecation I believe.

[exarkun]

objgrep is awfully handy for certain kinds of debugging. modgrep is maybe an unnecessary helper, but it's hardly a lot of code. If these aren't in Twisted, then I'll have to find some other way to keep them around to use them, that'll probably be annoying.