feat: Print summary information after row validation

[helensilva14]

Description of changes

Write a description of the changes you have made in this PR. Extremely small changes such as fixing typos do not need a description.

• data_validation/__main__.py: removed TODO comment for an issue already closed (CLI Support for Parallel Validation Execution #31)
• data_validation/combiner.py: implemented get_summary function to log a summary report only of row validation results, including statistics on rows present in source but not in target, and vice versa; added type checking and type hinting for all functions' parameters in the file; added a called to get_summary on function generate_report before returning its result.
• data_validation/result_handlers/bigquery.py: updated code comment
• tests/unit/test_combiner.py: implemented unit test for get_summary function

Issues to be closed

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Closes #1277
Closes #1414

Checklist

• I have followed the CONTRIBUTING Guide.
• I have commented my code, particularly in hard-to-understand areas
• I have added unit and integration tests relevant to my change as needed
• I have updated any relevant documentation to reflect my changes

[nj1973]

Just a few minor comments and one that I think we should not go down this route and discuss other options.

Approach refactored from initial review

[sundar-mudupalli-work]

Helen,

This is really close. What the customer is asking for ROW validation

1. Number of rows in the Source table - this is basically length of source_df
2. Number of rows with validation success - this you have calculated use that
3. Number of rows present in source and target, but failed validation - this is basically all failures where source_agg_value is not NULL and target_agg_value is not NULL
4. Number of rows present in source, but not in target - this is basically all failures where source_agg_value is not NULL and target_agg_value is NULL

Similarly for the target table.

I think these are additional conditions that you can run on the Pandas table. Please try it out and if you run into difficulty, we can work on it together.

Thanks.

Sundar Mudupalli

[helensilva14]

/gcbrun

[helensilva14]

/gcbrun

[sundar-mudupalli-work]

Helen,

Thank you for completing this - very helpful - Neil can take it to his customer.
Also thank you for using good coding practices by including typing - I call that the gift that you gave us that keeps on. giving - in the form of clarity when making other changes.

Thanks.

Sundar Mudupalli