fix: error checking prior to file writes

[meganwolf0]

Description

Adds functionality to validate if the desired output files for validate and compose are valid OSCAL models. Also a few additional error detail.

Related Issue

Fixes #678

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

Checklist before merging

• Test, docs, adr added or updated as needed
• Schema Updates applied
• Contributor Guide Steps followed

[brandtkeller]

I'm looking at some slight restructuring of the OSCAL pkg as is - Nonetheless I believe your adjustment to validate nails the intent of the (current) discussion in the issue -> checking output validity before executing any processing logic.

Do we want to map this behavior to all locations that would merge processed data with an existing file?

[meganwolf0]

Do we want to map this behavior to all locations that would merge processed data with an existing file?

Sure, I think the only one that would be missing is generate? Did I miss something else?

[brandtkeller]

Do we want to map this behavior to all locations that would merge processed data with an existing file?

Sure, I think the only one that would be missing is generate? Did I miss something else?

Thinking about the paths now - otherwise I think the only distinction I would make is repeating the pattern of checking for validity of the output file before processing - so scenarios like evaluate might need checking up-front as well.

[meganwolf0]

so scenarios like evaluate might need checking up-front as well.

It looks like evaluate sort of already has this built in - the first thing it does is grab all the files passed in and convert them to assessment-results, which should basically act as a validation of the output (since the output file is the input file)?

[brandtkeller]

Talked through how evaluate actively performs this functionality to-date. Covers known paths where a merge operation is expected and handles the check before performing any processing cycles