refactor get_data_for_analysis

[igusher]

My main goal is to change responsibilities a bit between classes in order to modularize computations so that later we can reuse some chunks in distributed environment.

The first thing I want to do - is to encapsulate computational logic in StatisticalTest. As it will be a building block in distributed environment and one StatisticalTest can run independently from the other. (Of course later StatisticalTestSuite will collect all Tests and correct them)
....
And I will do it in baby-steps so that you can see if I break any existing assumptions.

[igusher]

Well, exactly this change is trying to improve code according to Law of Demeter

[coveralls]

Coverage increased (+0.1%) to 92.406% when pulling a567607 on igusher:refactoring/encapsulate-some-methods-into-statistical-test into 99908d1 on zalando:master.

[igusher]

I've changed classes which are derived from JsonSerializable.
Could it potentially break existing serialization ?

[daryadedik]

@igusher can it be reviewed or it's in progress?

[igusher]

@daryadedik Yes, this one is ready for review.

[aaron-mcdaid-zalando]

This breaks very many of the ExpanService tests

The errors are usually something to do with serializing weakref:

AttributeError: 'weakref' object has no attribute '__dict__'
ERROR:ExpanService:'weakref' object has no attribute '__dict__'

[igusher]

@aaron-mcdaid-zalando What is an ExpanService? I'm not aware of it. I'm just a random contributor to an exapn lib :)
Do you know when and how it attempts to serialize weakrefs? which objects are those?