Graphite metrics coverage

[ham1]

Description

Added TextGraphiteMetricsSenderSpec to provide some coverage of TextGraphiteMetricsSender and PickleGraphiteMetricsSender and PickleGraphiteMetricsSenderSpec. Also cleaned up code in the surrounding area.

Motivation and Context

More tests!

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.

[ham1]

I have some questions for everyone:

1. I've removed the .clear() from the lists after sending because this didn't seem to be required as there will no longer be a reference to the list, therefore will be GC'd, this should also make sending slightly more efficient.
2. I've added an overloaded setup method to TextGraphiteMetricsSender to enable testing, is there a better/preferred way? e.g. should it be protected or private or a new constructor?
3. should destroy() also set metrics to null or are we relying on the original reference to be removed after destroy is called?

[pmouawad]

Did you check if use of lambda here would impact negatively performances ? (As per other PR discussion ?)

Thanks

[pmouawad]

Hi @ham1 ,
Thanks for this very useful PR.
Except for the forEach note, I am ok with code.
Could you check and either keep previous form or keep it if lambda is not counter performant.

Thanks