Fixes incomplete bless

[jasonb5]

Description

If a test's case directory is invalid the bless_test_results would preemptively exit, and result in a partial bless.

• Fixes incomplete bless when case is invalid
• Refactors bless_test_results
• Adds unittests

Checklist

• My code follows the style guidlines of this proejct (black formatting)
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have added tests that excerise my feature/fix and existing tests continue to pass
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding additions and changes to the documentation