Feature distribution changes - migrated tests to Pytest, use of abstract base classes

[ronanstokes-db]

Proposed changes

Leverage abstract base classes in keeping with implementation of constraints, migrated tests to Pytest

Types of changes

What types of changes does your code introduce to dbldatagen?
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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Change to tutorials, tests or examples
• Non code change (readme, images or other non-code assets)
• Documentation Update (if none of the other choices apply)

Checklist

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If you're unsure about any of them, don't hesitate to ask. We're here to help!
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• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules
• Submission does not reduce code coverage numbers
• Submission does not increase alerts or messages from prospector / lint

Further comments

Use of abstract base classes as general pattern for any pluggable aspects

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 92.59%. Comparing base (82ce5ce) to head (edc57c6).

Files	Patch %	Lines
dbldatagen/distributions/data_distribution.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #277      +/-   ##
==========================================
- Coverage   92.62%   92.59%   -0.04%     
==========================================
  Files          33       33              
  Lines        2998     2996       -2     
  Branches      523      522       -1     
==========================================
- Hits         2777     2774       -3     
- Misses        131      132       +1     
  Partials       90       90              

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[howardwu-db]

Looks good. There is a codecov issue but dont know how you would test that