295_place_holder (not a pull request)

[jimrothstein]

Issue #295 Proposed approach to unit tests for sdtmchecks::diff_reports

• In method ( to be determined ) construct TWO fictious reports that run_all_checks might generate
• Test here that diff_reports catches differences in the TWO reports correctly.
• Repeat this process, in a systematic way, so that diff_reports correctly handles differences in any of the many sdtmchecks or combinations.
• To test small differences between 2 reports, the testing code will manually adjust data before the comparison is run.
• For larger differences, two or more reports coulld be specially repaired, saved to storage and run as needed.

This is an iniital look at the code, not for pull request, and mostly for my benefit that I am on the right path.